Polar Bear - Conservation Management Plan

U.S. Fish and Wildlife Service

Polar Bear

Conservation Management Plan

Disclaimer:

This Conservation Management Plan (Plan) delineates reasonable actions we, the U.S. Fish and Wildlife

(USFWS), believe will contribute to the conservation and recovery of polar bears (Ursus maritimus). Funds

necessary to achieve the objectives identiﬁed in this Plan are subject to budgetary and other constraints,

as well as the need to address other agency priorities. This Plan does not necessarily represent the views,

ofﬁcial positions, or approval of any individuals or agencies involved in its formulation, other than USFWS.

The approved Plan will be subject to modiﬁcation as dictated by new ﬁndings, changes in species status, and

the completion of conservation management actions.

This Plan represents the views and interpretations of the USFWS regarding the conservation and recovery

of the polar bear only. USFWS’s approach set forth in this polar bear Conservation Management Plan does

not necessarily preclude other approaches in developing Endangered Species Act recovery plans or Marine

Mammal Protection Act conservation plans.

Literature citation should read as follows:

Citation: U.S. Fish and Wildlife. 2016. Polar Bear (Ursus maritimus) Conservation Management Plan,

Final. U.S. Fish and Wildlife, Region 7, Anchorage, Alaska. 104 pp.

The Plan was written by Michael C. Runge and Jenifer Kohout, with signiﬁcant written contributions

from Todd Atwood, Mary Colligan, Dave Douglas, Karen Oakley, Eric Regehr, Karyn Rode, Christopher

Servheen, Rhonda Sparks, Kim Titus, Jim Wilder, and Ryan Wilson.

The Plan can be downloaded from:

https://www.fws.gov/alaska/ﬁsheries/mmm/polarbear/pbmain.htm

Polar bear cover photos, USFWS

Polar Bear Conservation Management Plan 1

Polar Bear Conservation Management Plan

Prepared by the Polar Bear Recovery Team:

Region 7

U.S. Fish and Wildlife Service

Anchorage, Alaska

Approved:

/s/ Gregory E. Siekaneic

Regional Director, U.S. Fish and Wildlife Service

Date: 20 December 2016

2 Polar Bear Conservation Management Plan

Acknowledgments

USFWS gratefully acknowledges the commitment and efforts of the following current and former Recovery

Team members. Without their assistance and participation, this Plan, and the conservation we hope will

come from its recommendations, would not be possible.

Michael C. Runge (Recovery Team & Policy

Work Group Co-Chair) — U.S. Geological

Survey

Jenifer Kohout (Recovery Team & Policy

Work Group Co-Chair) — U.S. Fish and

Wildlife Service

Todd Atwood (Science & TEK Work Group

Co-Chair) — U.S. Geological Survey

Eric Regehr (Science & TEK Work Group Co-

Chair) — U.S. Fish and Wildlife Service

Paul Laustsen (Communications Work Group

Co-Chair) — U.S. Geological Survey

Sara Boario (Communications Work Group

Co-Chair) — U.S. Fish and Wildlife Service

Kim Titus — Alaska Department of Fish and

Game

Douglas Vincent-Lang — Alaska Department

of Fish and Game

Jack Omelak — Alaska Nanuuq Commission

Rhonda Sparks — Alaska Nanuuq

Commission

Joshua Kindred — Alaska Oil & Gas

Association

Dave Yokel — Bureau of Land Management

Lisa Toussaint — Bureau of Ocean Energy

Management

Basile Van Havre — Canadian Wildlife

Service

Caryn Rea — ConocoPhillips Alaska, Inc.

Karla Dutton — Defenders of Wildlife

Mike Gosliner — Marine Mammal

Commission

Peter Boveng — National Oceanic &

Atmospheric Administration

Taqulik Hepa — North Slope Borough

Tom Lohman — North Slope Borough

Mike Pederson — North Slope Borough

Andrew Von Duyke — North Slope Borough

Geoffrey S. York — Polar Bears International

Elisabeth Kruger — World Wildlife Fund

Dave Douglas — U.S. Geological Survey

Karen Oakley — U.S. Geological Survey

Karyn Rode — U.S. Geological Survey

Mary Colligan — U.S. Fish and Wildlife

Service

Charles Hamilton — U.S. Fish and Wildlife

Service

Kurt Johnson — U.S. Fish and Wildlife

Service

Andrea Mederios — U.S. Fish and Wildlife

Service

Katrina Mueller — U.S. Fish and Wildlife

Service

Jeff Newman — U.S. Fish and Wildlife

Service

Christopher Servheen — U.S. Fish and

Wildlife Service

Ted Swem — U.S. Fish and Wildlife Service

James Wilder — U.S. Fish and Wildlife

Service

Deborah Pierce Williams — U.S. Fish and

Wildlife Service

Ryan Wilson — U.S. Fish and Wildlife Service

Polar Bear Conservation Management Plan 3

Contents

ExEcutivE Summary ........................................................................................................................................ 5

Plan Philosophy .......................................................................................................................................... 5

The Primary Threat to Polar Bears ......................................................................................................... 6

Conservation Strategy ............................................................................................................................... 6

Management Goals and Criteria .............................................................................................................. 6

Conservation/Recovery Actions ............................................................................................................... 7

i. Background .................................................................................................................................................. 9

The Primary Threat to Polar Bears ....................................................................................................... 10

ii. conSErvation StratEgy ........................................................................................................................... 13

iii. managEmEnt goalS and critEria ....................................................................................................... 14

A. Fundamental Goals .............................................................................................................................. 14

B. Conservation Criteria under the Marine Mammal Protection Act ............................................... 19

MMPA fundamental criteria .............................................................................................................. 19

Basis for the MMPA fundamental criteria ....................................................................................... 19

MMPA demographic criteria .............................................................................................................. 21

C. Recovery Criteria under the Endangered Species Act .................................................................. 24

ESA fundamental criteria .................................................................................................................. 24

Basis for the ESA recovery criteria .................................................................................................. 24

ESA demographic criteria .................................................................................................................. 26

ESA threats-based criteria ................................................................................................................ 29

D. Other Measures of Achievement ....................................................................................................... 33

E. The Population Dynamics of Conservation, Recovery, and Harvest ............................................ 34

A picture of conservation .................................................................................................................... 34

A picture of recovery ........................................................................................................................... 36

The compatibility of harvest with conservation and recovery ...................................................... 37

F. Uncertainty, Assumptions, and the Need for Adaptive Feedback and Management ................. 39

iv. conSErvation managEmEnt StratEgy .................................................................................................. 40

A. Collaborative Implementation ........................................................................................................... 40

B. Conservation and Recovery Actions ................................................................................................. 42

Limit global atmospheric levels of greenhouse gases to levels appropriate for supporting polar bear

recovery and conservation, primarily by reducing greenhouse gas emissions ........................... 42

Support international conservation efforts through the Range States relationships ............... 43

Manage human-polar bear conﬂicts .................................................................................................. 44

Collaboratively manage subsistence harvest ................................................................................... 45

Protect denning habitat ...................................................................................................................... 47

Minimize risk of contamination from spills ..................................................................................... 47

Conduct strategic monitoring and research .................................................................................... 48

4 Polar Bear Conservation Management Plan

v. litEraturE citEd ...................................................................................................................................... 53

vi. gloSSary ................................................................................................................................................... 58

appEndix a— Background .......................................................................................................................... 61

appEndix B— SpEcific conSErvation and rEcovEry actionS conSidErEd ......................................... 91

appEndix c—population dynamicS and HarvESt managEmEnt ........................................................... 97

Polar Bear Conservation Management Plan 5

Executive Summary

Today, polar bears roam the northern reaches of

the planet, but as their sea-ice habitat continues

to shrink due to Arctic warming, their future in

the U.S. and ultimately their continuation as a

species are at risk. Their eventual reprieve turns

on our collective willingness to address the factors

contributing to climate change and, in the interim,

on our ability to improve the chances that polar

bears survive in sufﬁcient numbers and places

so that they are in a position to recover once the

necessary global actions are taken.

Polar bears are an ice-dependent species that rely

on sea ice as a platform to hunt ice seals and to

raise their young. The current global polar bear

population is estimated to be 22,000 to 31,000.

Polar bears range across 5 Arctic nations; for

management purposes, their population is divided

into 19 subpopulations. These subpopulations have

been further grouped into four ecoregions based

on the spatial and temporal dynamics of sea ice

in the subpopulations’ range. The near- and mid-

term impacts of sea-ice loss on polar bears will

vary among subpopulations and ecoregions but

over the long term, those impacts are anticipated

to be signiﬁcant for polar bear numbers range wide

if global greenhouse gas emission levels are not

signiﬁcantly reduced.

PLAN PHILOSOPHY

The Polar Bear Conservation Management Plan

(Plan) was developed as a practical guide to

implementation of polar bear conservation in the

United States. From a legal perspective, the purpose

of the Plan is to articulate the conditions whereby

polar bears would no longer need the protections

of the Endangered Species Act (ESA) and to lay

out a collective strategy that moves us towards

achieving those conditions. A parallel path is laid out

for improving the status of polar bears under the

Marine Mammal Protection Act (MMPA).

Many governmental and non-governmental

agencies, institutions, and organizations are

currently involved in polar bear conservation. These

entities are integral to the conservation of the

species. Going forward, conservation of polar bears

will require the collective will and collaboration of

nations and Native communities, of government

agencies and private organizations, of scientists

and subsistence hunters. This Plan reﬂects the

diverse input of several of those stakeholders. It also

emphasizes local engagement, from the oil and gas

industry activities on the North Slope of Alaska that

keep employees safe and minimize defense-of-life

kills, to the Alaska Native peoples who have lived

with and depended on polar bears for thousands

of years and will be integral to conservation of the

species going forward.

Although the Plan satisﬁes the statutory

requirements of the ESA and the MMPA, it is

more broadly focused than a typical recovery or

conservation plan. At its core, the Plan contains

a set of fundamental goals reﬂecting shared

values of diverse stakeholders. The goals focus on

conservation of polar bears while recognizing values

associated with subsistence take, human safety, and

economic activity.

USFWS

6 Polar Bear Conservation Management Plan

Executive Summary

These fundamental goals are described in

quantitative terms associated with ESA and MMPA

requirements, and are stepped down to measurable

demographic and threats-based criteria. The Plan

identiﬁes a suite of high priority conservation and

recovery actions to achieve those criteria. Strategic

monitoring will focus both on implementation (the

extent to which the plan is followed and recovery

actions are taken) and effectiveness (the extent to

which recovery actions are successful and progress

is made).

This Plan is meant to be a dynamic, living document

and is expected to be revised periodically as new

knowledge becomes available. Recognizing the

uncertainties inherent in polar bear management,

monitoring and research are integral to

implementation. As new information is gathered

to track and evaluate progress, it should feed back

into the Plan, allowing revision of the conservation

and recovery criteria, as well as reﬁnement of the

conservation strategy.

THE PRIMARY THREAT TO POLAR BEARS

As identiﬁed in the ﬁnal rule listing the polar bear

as a threatened species under the ESA, the decline

of sea ice habitat due to changing climate is the

primary threat to polar bears (73 FR 28211). The

single most important achievement for polar bear

conservation is decisive action to address Arctic

warming (Amstrup et al. 2010, Atwood et al. 2016),

which is driven primarily by increasing atmospheric

concentrations of greenhouse gases. Short of

action that effectively addresses the primary cause

of diminishing sea ice, it is unlikely that polar

bears will be recovered. Addressing the increased

atmospheric levels of greenhouse gases that are

resulting in Arctic warming will require global

action. While this Plan calls for action to promptly

reduce greenhouse gas emissions, the focus is on

wildlife management actions within the United

States that will contribute to the survival of polar

bears in the interim so that they are in a position to

recover once Arctic warming has been abated.

CONSERVATION STRATEGY

Along with the threat posed by sea-ice loss and

the inadequacy of existing regulatory mechanisms

to address climate change, other current or

potential sources of polar bear mortality will

likely become more signiﬁcant going forward.

Potential management concerns in the U.S. include

human-bear conﬂicts and defense-of-life removals,

subsistence harvest, loss of denning habitat, and

contamination from spills. This plan outlines actions

the U.S. Fish and Wildlife Service (USFWS) and

its partners (“we”) can take to preclude these from

threatening the persistence or recovery of polar

bears while the global community works to address

and limit atmospheric levels of greenhouse gases.

MANAGEMENT GOALS AND CRITERIA

Polar bears are important to humans for many

reasons. In seeking an enduring, collaborative

strategy for management, this Plan recognizes

the array of values held by diverse communities

engaged in polar bear conservation. The Plan

proposes six Fundamental Goals. The ﬁrst three

involve securing the long-term persistence of

polar bears on different geographic scales: (1)

range-wide (the global scale of the ESA listing);

(2) ecoregions (an intermediate scale that reﬂects a

goal of maintaining intraspeciﬁc diversity); and (3)

the State of Alaska (encompassing the 2 polar bear

subpopulations partially within the United States).

Fundamental Goal 4 recognizes the nutritional and

cultural needs of native peoples with connections to

polar bear populations, including the opportunity for

harvest of polar bears for subsistence purposes as

that term is understood in the context of U.S. laws.

Fundamental Goal 5 calls for continued management

of human-bear interactions to ensure human safety

and to conserve polar bears. Finally, Fundamental

Goal 6 seeks to achieve polar bear conservation

while minimizing restrictions to other activities

within the U.S. range of the polar bear, including

economic development.

Two criteria are identiﬁed as guidance for our

management actions under the MMPA. The ﬁrst

calls for maintenance of the “health and stability of

the marine ecosystem” and for polar bears to retain

their role as a “signiﬁcant functioning element of the

ecosystem,” as reﬂected in maintenance of at least

70% of the historical carrying capacity for polar

bears. The second is a take-based criterion requiring

that the rate of direct human-caused removals

maintains a subpopulation above its maximum

net productivity level (mnpl) relative to carrying

capacity.

The ESA recovery criteria for delisting are

expressed at a fundamental level for two

geographic scales. At the scale of the listed species,

the fundamental criterion is that probability

of persistence worldwide be at least 95% over

100 years. This Plan identiﬁes 4 recovery units,

corresponding to four polar bear ecoregions. At

this intermediate scale, the fundamental criterion

is that the probability of persistence in each of the 4

recovery units be at least 90% over 100 years.

The ESA demographic criteria focus on four

measures of population status: survival rate,

recruitment rate, carrying capacity, and the rate

of human-caused removals. Recovery is achieved

when all of the following conditions are met in each

recovery unit: (i) the mean adult female survival rate

is at least 93-95% (currently and as projected over

100 years); (ii) the ratio of yearlings to adult females

is at least 0.1-0.3 (currently and as projected over

100 years); (iii) the carrying capacity, distribution,

Polar Bear Conservation Management Plan 7

Executive Summary

and connectivity in each recovery unit, both

currently and as projected over the next 100 years,

are such that the probability of persistence over 100

years is at least 90%; and (iv) the rate of human-

caused removals maintains the population in each

recovery unit above its maximum net productivity

level relative to carrying capacity.

The Plan then identiﬁes ESA threats-based criteria

representing the levels at which sea-ice loss and

human-caused removals would not be considered

a threat under the ESA. Sea-ice loss, the primary

threat identiﬁed in the 2008 listing determination,

will cease to be a threat to polar bear recovery

when the average duration of the ice-free period

in each recovery unit (i) is expected not to exceed

4 months over the next 100 years based on model

projections, or (ii) is expected to stabilize at longer

than 4 months and there is evidence that polar bears

can meet the demographic criteria (above) under

that longer ice-free period. Human-caused removals

were not identiﬁed as a threat in the 2008 listing

rule. However, the rule recognized the potential that

they could become a threat to polar bear recovery,

in particular as populations are affected by sea-ice

loss. This would be the case if those human-caused

removals reduce the probability of persistence

below 90% over 100 years in any of the 4 recovery

units. Potential future management concerns posed

by disease, oil and gas activities, contamination

from spills, and increased Arctic shipping are

acknowledged but, because these factors have not

been identiﬁed as threats at present, no recovery

criteria are associated with them.

To achieve recovery under the ESA, the criteria at

all three levels—fundamental, demographic, and

threats-based—must be met.

CONSERVATION/RECOVERY ACTIONS

The Plan identiﬁes a strategic suite of high priority

conservation and recovery actions. The ﬁrst and

foremost action for the purpose of recovery is

to stop Arctic warming and the loss of sea ice

by limiting atmospheric levels of greenhouse

gases. The principal mechanism for doing that

is to substantially reduce global greenhouse gas

emissions. Other actions, which can be implemented

by USFWS and its partners, are aimed at the near-

and mid-term goal of providing polar bears in the

U.S. the best possible chance of persisting when

climate change has been addressed and further

Arctic warming has stopped. These actions include

managing human-bear conﬂicts, collaboratively

managing subsistence harvest, protecting denning

habitat, and minimizing the risk of contamination

from spills. While the focus of this plan is primarily

on actions in the U.S., priority actions also

include collaborating with Canada and Russia on

management of the 2 subpopulations for which the

U.S. shares oversight.

Along with these actions, the Plan calls for

monitoring and research speciﬁcally targeting the

information needed to assess the Plan’s criteria and

guide the Plan’s actions. Strategic monitoring will

enable us to determine whether our actions, and

this Plan, are effective in the near- and mid-term at

conserving polar bears or whether they need to be

modiﬁed.

Finally, to facilitate implementation of these actions,

the Plan envisions continuation of the Recovery

Team in the form of a collaborative Implementation

Team. The Implementation Team will meet on a

regular basis to share information, revisit priorities,

and leverage resources.

USGS

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I. Background

I. BACKGROUND

Figure 1. Map of the polar bear subpopulations (source: Polar Bear Specialist

Group). The subpopulations include: Southern Beaufort Sea (SB), Chukchi Sea,

Laptev Sea, Kara Sea, Barents Sea, East Greenland, Northern Beaufort (NB), Kane

Basin (KB), Norwegian Bay (NW), Lancaster Sound (LS), Gulf of Boothia (GB),

M’Clintock Channel (MC), Viscount Melville Sound (VM), Bafﬁn Bay, Davis Strait,

Foxe Basin, Western Hudson Bay (WH), Southern Hudson Bay and the Arctic Basin

(AB).

Polar bears occur in 19 subpopulations throughout

the seasonally and permanently ice-covered marine

waters of the northern hemisphere (Arctic and

Subarctic), in Canada, Denmark (Greenland),

Norway, Russia, and the United States (Fig. 1). The

United States contains portions of two subpopula-

tions: the Chukchi Sea and the Southern Beaufort

Sea. These 2 subpopulations have also been identi-

ﬁed as “stocks” under the MMPA.

Polar bear subpopulations have been further

classiﬁed as occurring in one of four ecoregions (Fig.

2, Amstrup et al. 2008) based on the spatial and

temporal dynamics of sea ice in the subpopulation’s

range. Subpopulations classiﬁed as occurring in the

Seasonal Ice Ecoregion share the characteristic that

the sea ice in their range fully melts in the summer,

during which time bears are forced on shore for

extended periods of time until the sea ice reforms.

Subpopulations occurring in the Archipelago

Ecoregion are characterized as having heavy

annual and multi-year sea ice that ﬁlls the channels

between the Canadian Arctic Islands. Bears in this

ecoregion remain on the sea ice throughout the

year. The Polar Basin Divergent Ecoregion, which

includes the two United States subpopulations, is

characterized by the formation of annual sea ice

that is swept away from the shore as sea ice melts

during the summer. The Polar Basin Convergent

Ecoregion is characterized by annual sea ice that

converges towards shoreline, allowing bears access

to nearshore ice year-round. Although information

is limited, the global genetic structure of polar bears

appears to reﬂect the four ecoregions (Paetkau et al.

1999, Peacock et al. 2015).

The most recent circumpolar population estimate

by the IUCN Red List Assessment was 26,000 (95%

Conﬁdence Interval of 22,000 to 31,000) polar bears

(Wiig et al. 2015).

Polar Bear Conservation Management Plan 9

I. Background

Figure 2. Ice ecoregions (Amstrup et al. 2008). These ecoregions are equated with ESA

recovery units in this Plan.

Polar bears are relatively long-lived, and are

characterized by late sexual maturity, small litter

sizes, and extended maternal investment in raising

young. These are all factors that contribute to a low

reproductive rate; as a result, high adult survival

rates, particularly of females, are required to

maintain population levels. Survival rates exceeding

93 percent for adult females are essential to sustain

polar bear subpopulations (Regehr et al. 2015).

Sea ice is the primary habitat for polar bears. Polar

bears depend on sea ice as a platform on which

to: hunt and feed on seals; seek mates and breed;

travel to terrestrial maternity denning areas; den;

and make long-distance movements. Polar bear

movements are closely tied to the seasonal dynamics

of sea-ice extent as it retreats northward during

summer melt and advances southward during

autumn freeze.

A more detailed biological background can be found

in Appendix A.

The United States Fish and Wildlife Service

(USFWS) listed the polar bear (Ursus maritimus)

as a threatened species under the Endangered

Species Act of 1973 as amended (ESA) on May 15,

2008 (73 FR 28211); as a result, it automatically

became a “depleted” species under the Marine

Mammal Protection Act of 1972 as amended

(MMPA).

The USFWS has four purposes for this Plan. The

ﬁrst is to meet the recovery planning requirement

of the ESA. Section 4(f) directs the USFWS to

develop plans for listed species which identify

“objective, measurable” recovery criteria and

site-speciﬁc recovery actions with estimated time

and cost to completion (16 USC §1533(f)(1)(B)). The

second purpose is to develop a conservation plan

under the MMPA, patterned after ESA recovery

plans but with a goal of conserving and restoring a

species to its optimum sustainable population (16

USC § 1383 (b)). The third purpose is to create a

national plan related to management of polar bears

in the U.S. to be appended to the Circumpolar

Action Plan for Polar Bear Conservation developed

by the signatories to the 1973 Agreement on the

Conservation of Polar Bears. Those signatories

are the ﬁve countries with polar bear populations

(Canada, Denmark on behalf of Greenland, Norway,

the Russian Federation, and the United States),

known collectively as the “Range States.” Consistent

with the 1973 Agreement (Articles VII and IX), the

Range States prepared a Circumpolar Action Plan,

which will be supplemented by a national plan from

each country to describe the speciﬁc conservation

actions it will take, in accord with its domestic laws.

The ﬁnal purpose of this Plan is to provide a unify-

ing framework for conservation of polar bears by

partners within the United States.

The Primary Threat to Polar Bears

Sea ice is rapidly thinning and retreating

throughout the Arctic (Stroeve et al. 2012). Multiple

combined and interrelated events have changed

10 Polar Bear Conservation Management Plan

I. Background

USFWS

the extent and characteristics of sea ice during all

seasons, but particularly during summer. Arctic

warming is likely to continue for several decades

and possibly centuries given the current trends in

global greenhouse gas emissions (IPCC 2014), the

long persistence time of certain greenhouse gases in

the atmosphere (Moore and Braswell 1994), and the

lag times associated with global climate processes

attaining equilibrium (Mitchell 1989, Hansen et al.

2011). Hence, climate change effects on sea ice and

polar bears and their prey will very likely continue

for several decades or longer until increases in

atmospheric greenhouse gases are stopped.

The threats to polar bears identiﬁed in the ESA

listing determination were the loss of sea-ice

habitat due to climate change and the inadequacy

of existing mechanisms curtailing that threat (73

FR 28277). It cannot be overstated that the single

most important action for the recovery of polar

bears is to signiﬁcantly reduce the present levels

of global greenhouse gas (GHG) emissions, which

are the primary cause of warming in the Arctic.

Recently, Atwood et al. (2016) corroborated the

climate threat by determining through Bayesian

network modeling that the most inﬂuential driver of

adverse polar bear outcomes in the future will likely

be declines in sea-ice conditions, and secondarily

declines in the marine prey base. Mortality from in

situ anthropogenic factors like hunting and defense

of life will likely exert considerably less inﬂuence

on future polar bear population outcomes, while

stressors such as trans-Arctic shipping, oil and

gas exploration, development, and production, and

point-source pollution appear to impose little risk to

the long-term persistence of polar bears.

The levels that global greenhouse gas emissions

reach in the coming decades will have a tremendous

inﬂuence on the abundance and distribution of

polar bears in the future. Polar bears will likely be

extirpated from much of their present-day range if

emissions continue to rise at current rates through-

out the 21st century (Amstrup et al. 2008); however,

if the rise in global mean temperature can be kept

below 2 degrees C, which could only be accom-

plished by prompt and very aggressive reductions in

worldwide GHG emissions, the probability of greatly

reduced polar bear populations could be substantial-

ly lowered (Atwood et al. 2016). The best prognosis

for polar bears entails aggressive GHG mitigation

combined with optimal polar bear management

practices, which together could maintain viable

polar bear populations in most regions of the Arctic

(Fig. 3, Amstrup et al. 2010). To that end, this Plan

provides a framework for USFWS and its partners

to accomplish the latter goal, while governments,

industries, and citizens throughout the world aspire

to accomplish the former.

There are positive signs. Parties to the United

Nations Framework Convention on Climate Change

(UNFCCC) agreed at their Paris meeting in Decem-

ber 2015 to the goal of “holding the increase in the

global average temperature to well below 2°C above

pre-industrial levels and to pursue efforts to limit

the temperature increase to 1.5°C” (Article 2.1(a),

United Nations 2015). Although the self-determined

pledges by each nation toward reducing their emis-

sions over the next 10–15 years are non-binding and

currently insufﬁcient to keep warming under 2°C,

the Parties have agreed to work together to increase

those pledges before 2020. If the Paris Agreement’s

central aim to keep global warming well below 2°C

can be achieved, it is far more likely that polar bears

Arctic-wide can be fully recovered because the

threat of sea-ice loss will be signiﬁcantly curtailed in

all recovery units.

Figure 3 illustrates the markedly different levels

of impact on polar bear habitat during summer

that result when hypothetical best-case (Fig. 3a)

Polar Bear Conservation Management Plan 11

I. Background

and worst-case (Fig. 3c) scenarios of future GHG

emissions are compared. The ﬁgure shows coastal

areas where polar bears could come ashore during

summer and spend no more than 4 months before

the sea ice returned, a period of food deprivation

that polar bears are well-adapted to accommodate

assuming they have adequate advance access to

prey (Molnár et al. 2010, 2014; Robbins et al. 2012).

If present rates of GHG emissions were to continue

unabated to century’s end (a worst-case scenario,

Fig. 3c), limited areas in the Canadian Archipelago

and northern Greenland might be suitable for polar

bears to occupy during summer, or possibly not,

because half of the climate models project ice-free

conditions lasting ≥5 months (a point when modeled

effects of food deprivation become more severe;

Molnár et al. 2010, 2014) Arctic-wide. The possibility

for such extreme summer sea ice melt under the

worst-case GHG emissions scenario raises concerns

for polar bear persistence, especially since prey

abundances could also be negatively impacted by

changes to the Arctic Ocean’s food web (Arrigo et

al. 2008; Hoegh-Guldberg and Bruno 2010; Schoﬁeld

et al. 2010; Tremblay et al. 2015). In stark contrast,

Fig. 3a shows end-of-century outcomes for a best-

case scenario in which GHG emissions are promptly

and very aggressively reduced to levels that keep

average global warming below 2°C (relative to the

preindustrial era). The aims of the Paris Agreement,

adopted by 195 countries in 2015 (United Nations

2015), calls for such aggressive GHG mitigation. At

century’s end under an aggressively mitigated GHG

emissions scenario (Fig. 3a), all models agree that

most coastal areas in the Canadian Archipelago and

northern Greenland could be used by polar bears

during summer without undue risk of becoming

stranded onshore for more than 4 months, and

perhaps similarly for areas in Russia, which would

improve the chances of polar bears persisting in all

4 ecoregions. Achieving the levels of mitigation put

forth by the Paris Agreement is arguably tentative,

however, in that it requires timely and unprec-

edented global commitments as well as unproven

technological advances (Tollefson 2015; Smith et al.

2016). If GHG emissions are promptly mitigated

and stabilized (Fig. 3b), all or most climate models

project the Canadian Archipelago and northern

Greenland could be used by polar bears during

summer (like Fig. 3a), while only half the models or

fewer project suitable coastal areas throughout the

rest of the Arctic.

The future for polar bears is yet to be determined,

and while many sources of uncertainty preclude

our ability to precisely forecast their future status

(Douglas and Atwood 2017), the sooner global

warming and sea ice loss are stopped, the better

the long-term prognosis for the species. To this end,

we endorse efforts everywhere, big and small, to

mitigate greenhouse gas emissions in an ecologically

sound manner, and emphasize the direct and imme-

diate relationship between success in these efforts

and the future status of the polar bear.

Figure 3. Coastal areas where polar bears could come

ashore for no more than 4 months during each summer

of the last decade of the 21st century (2091–2100),

as projected by 6 global climate models forced with 3

greenhouse gas emission scenarios. With increasing

emissions (Representative Concentration Pathway

[RCP] 2.6, 4.5, and 8.5 respectively), coastal areas where

the offshore summer ice-free period is projected to be 4

months or less in duration occur in fewer areas, and are

corroborated by fewer models. Colors along the coast-

lines denote the level of agreement among the 6 models

analyzed; greater uncertainty exists when fewer models

agree. Inset shows the observed rise in atmospheric CO

from 1950–2014 (black line) and the scenario-speciﬁc

change from 2015–2100 (red line). Figure from Douglas

and Atwood (2017).

12 Polar Bear Conservation Management Plan

II. Conservation Strategy

II. CONSERVATION STRATEGY

Although the need to reduce emissions contributing

to climate change has been recognized in national

plans (President’s Climate Action Plan, White

House 2013b) and action by the USFWS and other

agencies (EPA proposed carbon pollution standards

for existing stationary sources, 79 FR 34830 et seq.),

more needs to be done in the United States and

around the globe to slow the warming trends that

are harming Arctic ecosystems and polar bears,

which depend on those ecosystems and play an

integral role in their functioning.

Recognizing that USFWS lacks the authority to

regulate greenhouse gas emissions, we must rely

on the United States and other nations to address

the emissions that are the primary contributor to

ongoing climate change, whether such reductions

are via laws, regulations, market-based incentives,

or a combination of approaches. Under this Plan,

our speciﬁc contribution toward curbing global

emissions will be a science-based communication

effort highlighting the urgent need for signiﬁcant

reductions in emissions to help achieve a global

atmospheric level of greenhouse gases that will

support conditions for recovery of polar bears from

projected declines.

While global efforts are made to curb atmospheric

levels of greenhouse gases, there are actions the

USFWS and its partners can take in the U.S. that

will improve the ability of polar bears to survive

in the wild in sufﬁcient numbers and distribution

so that they are in a position to recover once the

threat of further Arctic warming has been removed.

Overutilization was not identiﬁed as a threat to

the species throughout all or a signiﬁcant portion

of its range. However, the listing rule noted that

continued efforts were necessary to ensure that

harvest or other forms of removal did not exceed

sustainable levels, particularly for subpopulations

experiencing nutritional stress or declining numbers

as a consequence of habitat change (73 FR 28280).

Even for populations affected to a lesser degree by

environmental changes and habitat impacts, the

rule noted that effective implementation of existing

regulatory mechanisms was necessary to address

issues related to overutilization (73 FR 28280).

Looking ahead, additional challenges to polar bear

conservation that may rise to the level of a threat

include disease, shipping, oil and gas activities, and

oil spills.

Speciﬁcally, our conservation strategy calls for the

following actions:

 Limit global atmospheric levels of

greenhouse gases to levels appropriate for

supporting polar bear recovery and conser-

vation, primarily by reducing greenhouse

gas emissions

 Support international conservation efforts

through the Range States relationships

 Manage human-bear conﬂicts

 Collaboratively manage subsistence harvest

 Protect denning habitat

 Minimize risks of contamination from spills

 Conduct strategic monitoring and research

The focus of this Plan is on those actions the

USFWS and its partners can take, primarily in the

U.S. These include actions with stakeholders and

partners to mitigate various forms of disturbance

and mortality, which although they are not currently

threats to polar bear subpopulations, may become

threats in the future. Conservation actions, many

of which are already underway, will be proactive,

informed by strategic monitoring, and carried out

with ongoing support from an Implementation

Team.

We will track the effectiveness of these actions in the

near- and mid-term by monitoring demographic and

threats-based criteria in the Polar Basin Divergent

ecoregion—a region where polar bears are highly

vulnerable to Arctic warming (Atwood et al. 2016)

and the home to both of the United States’ subpopu-

lations.

USFWS

Polar Bear Conservation Management Plan 13

III. Management Goals and Criteria

Fundamental Goals

The fundamental goals of the Polar Bear Conservation Management

Plan arise from the statutory obligations under the Marine Mammal

Protection Act and the Endangered Species Act, the goals of the

Circumpolar Action Plan, as well as the values of polar bear conserva-

tion partners in Alaska.

1. Secure the long-term persistence of wild polar bears as a species

and as a signiﬁcant functioning element in the ecosystem of which

they are a part.

2. Secure the long-term persistence of polar bears at scales that

represent the genetic, behavioral, life-history, and ecological

diversity of the species.

3. Secure the long-term persistence of the two polar bear subpopula-

tions in the United States (the Southern Beaufort Sea and Chukchi

Sea subpopulations).

4. Recognize the nutritional and cultural needs of native peoples with

connections to polar bear populations, including the opportunity

for continued harvest of polar bears.

5. Continue to manage human-bear interactions to ensure human

safety and to conserve polar bears.

6. Achieve polar bear conservation while minimizing restrictions

to other activities within the range of the polar bear, including

economic development.

III. MANAGEMENT GOALS AND CRITERIA

A. Fundamental Goals

The fundamental goals express the intentions of

this Plan and will be used to guide management,

research, monitoring, and communication. They

include the goals of the MMPA and the ESA, as they

relate to polar bear conservation and recovery, with

a particular focus on the U.S. The fundamental goals

also reﬂect the input and aspirations of stakehold-

ers closely connected with polar bears and their

habitat, including the State of Alaska, the North

Slope Borough, Alaska Native peoples, conservation

groups, and the oil and gas industry. In most cases,

the fundamental goals represent range-wide aspira-

tions, but the speciﬁc applications under this Plan

pertain primarily to the polar bear subpopulations

linked to Alaska.

The fundamental goals apply to three spatial scales:

the entire polar bear range, signiﬁcant regional

population segments (currently equated with ecore-

gions), and subpopulations in the United States.

They also reﬂect different temporal scales ranging

from long-term (~100 years, to reﬂect generational

goals), to mid-term (~50 years, to reﬂect steps to

put polar bears in the best position to recover once

the primary threat is addressed), to near-term.

Anticipating that polar bear populations are likely

to decline as sea ice recedes (73 FR 28212), some of

the goals reﬂect long-term desired outcomes, rather

than predictions of the likely future. In addition,

it may not be possible to achieve all of these goals

simultaneously and to their fullest degree. One of

the challenges in implementing this Plan will be

ﬁnding the right trade-off among these fundamental

goals, appropriately recognizing the statutory

guidance, as well as other social values.

14 Polar Bear Conservation Management Plan

III. Management Goals and Criteria

Fundamental Goal 1: Secure the long-term

persistence of wild polar bears as a species and as a

signiﬁcant functioning element in the ecosystem of

which they are a part.

The central purpose of this Plan, both in itself, and

as the United States’ contribution to the Range

States’ Circumpolar Action Plan, is to ensure that

polar bears remain in the wild on this planet, and

remain a signiﬁcant functioning element of the

Arctic ecosystem, long into the future. This central

purpose is readily shared by all stakeholders.

Species qualify for protection under the ESA if

they are in danger of extinction throughout all or

a signiﬁcant portion of their range (endangered)

or are likely to become so in the foreseeable future

(threatened). The aim of recovery efforts, therefore,

is to ensure survival and reduce the risk of extinc-

tion to the point that the species no longer requires

or qualiﬁes for protection under the ESA, rather

than to restore the species to historical levels.

The MMPA has speciﬁc provisions that apply to

“depleted” species, a status that applies to polar

bears as a species because of its ESA listing (16

USC §1362(1)). Congress found in the MMPA that

species and population stocks “should not be permit-

ted to diminish beyond the point at which they

cease to be a signiﬁcant functioning element in the

ecosystem of which they are a part, and consistent

with this major objective, they should not be permit-

ted to diminish below their optimum sustainable

population” (16 USC §1361(2)).

In 2008 the USFWS found that the polar bear is

likely to become an endangered species within the

foreseeable future throughout all of its range and

listed the species as threatened under the ESA (73

FR 28212). Thus, the focus of Fundamental Goal

1 is on polar bears as a species. The long-term

persistence aspect of this goal is especially related to

requirements of the ESA, and the role of the species

as a signiﬁcant functioning element in the ecosystem

is especially related to requirements of the MMPA.

Fundamental Goal 2: Secure the long-term

persistence of polar bears at scales that represent

the genetic, behavioral, life-history, and ecological

diversity of the species.

Beyond the goal of keeping polar bears extant in the

wild, and recognizing that Arctic warming will not

affect polar bear subpopulations equally, it is also

important to maintain a broad geographic distribu-

tion to conserve genetic, behavioral, ecological, and

life-history diversity. Applicable recovery planning

guidance developed jointly by National Marine

Fisheries Service (NMFS) and USFWS under the

ESA (NMFS and USFWS 2010) suggests recovery

units may be considered “to conserve genetic

robustness, demographic robustness, important life

history stages, or some other feature necessary for

long-term sustainability of the entire listed entity.”

In addition, although they apply explicitly to listing

decisions under the ESA, the “signiﬁcant portion

of the range” and “distinct population segment”

policies provide guidance regarding the importance

of intraspeciﬁc diversity. Under the MMPA, the

ﬁnding by Congress that marine mammals should

be maintained as signiﬁcant functioning elements of

their ecosystem supports the view that polar bears

should be conserved in more than a small portion of

their historic range. Intermediate-scale groupings of

polar bears capture important intraspecies genetic

and life-history diversity; as explained below, the

polar bear ecoregions (Amstrup et al. 2008) provide

a reasonable proxy of this diversity.

Beyond its fundamental importance, this goal also

serves as an effective means to secure the long-term

persistence of polar bears range-wide (Fundamental

Goal 1) and of polar bears in the United States

(Fundamental Goal 3). Conserving the broad spatial

distribution and ecological diversity of polar bears

over the near- and mid-term—while longer-term

solutions to climate change emerge—will provide

the greatest opportunity and ﬂexibility for future

actions to achieve the ESA and MMPA standards

and goals for polar bears.

Fundamental Goal 3: Secure the long-term

persistence of the two polar bear subpopulations in

the United States (the Southern Beaufort Sea and

Chukchi Sea subpopulations).

Conservation of polar bears in Alaska is important

for ecological, cultural, spiritual, economic, and

aesthetic values. To achieve desirable outcomes

associated with these values, securing persistent

populations of polar bears in the United States over

the long term is an important goal. Admittedly,

current predictions pointing to range reductions and

population declines highlight the aspirational nature

of this goal. In the short- and mid-term, forestalling

potential extirpation of polar bears from the United

States will serve as a means to achieve Fundamental

Goals 1 and 2.

This Plan seeks conservation and recovery of the

species range-wide, even if the primary focus of the

Plan’s conservation and recovery actions is on the

two United States subpopulations. The individual

management plans produced by the other Range

States to underpin the Range States’ Circumpolar

Action Plan will address additional actions for the

remaining subpopulations in a manner consistent

with each nation’s own statutory, cultural, and

Polar Bear Conservation Management Plan 15

III. Management Goals and Criteria

economic objectives as well as the 1973 Agreement

on the Conservation of Polar Bears. We acknowl-

edge and support the conservation actions of the

other Range States to the extent they contribute to

recovery of the species.

Fundamental Goal 4: Recognize the nutritional and

cultural needs of native peoples with connections to

polar bear populations, including the opportunity for

continued subsistence harvest of polar bears.

Local native communities throughout the Arctic

have a long tradition of living with polar bears.

Those communities have engaged in polar bear

harvest consistent with long-standing traditions

that provide for the nutritional and cultural needs of

communities and have been integral to the success

of polar bear conservation activities. Article III of

the 1973 Agreement on the Conservation of Polar

Bears allows harvest of polar bears in the exercise of

traditional rights of local people. Congress recog-

nized the cultural importance of subsistence harvest

to Alaska Native peoples in both the MMPA and the

ESA. The MMPA speciﬁcally allows non-wasteful

harvest of marine mammals, including those that are

depleted, by coastal-dwelling Alaska Native peoples

(take of polar bears from the Chukchi Sea subpopu-

lation is governed under Title V, 16 USC §1423). The

ESA similarly exempts Alaska Native subsistence

harvest from the prohibition on take of threatened

or endangered species. Commercial trade is not

authorized, however. This does not preclude creation

and sale of authentic Alaska Native handicrafts and

clothing as authorized by these two statutes. Both

the MMPA and ESA acknowledge the conservation

context of the subsistence exception by authorizing

the Secretary to regulate such harvest if necessary

(16 USC §1371(b), 16 USC §1539(e)).

This fundamental goal is intended to provide future

generations of Alaska Natives the opportunity to

meet nutritional and cultural needs through the

harvest of polar bears. Achievement of this goal will

require the continued responsible management of

harvest by Alaska Native peoples, other indigenous

peoples, the United States, and other Range States.

Fundamental Goal 5: Continue to manage human-

polar bear interactions to ensure human safety and

to conserve polar bears.

The likelihood of interactions between humans and

polar bears increases: as polar bears spend more

time on shore due to a number of factors including

receding sea ice; as their primary prey declines and

they seek alternative food; as the human population

near the Arctic coast increases; and as industrial

activity in the Arctic increases. Ensuring the safety

of people living and working in the coastal areas

frequented by polar bears is a paramount concern.

A secondary but important consideration for polar

bear conservation is the outcome of human-bear

interactions on polar bears. Frequent interactions

with people pose a threat to polar bears, both

directly, if bears have to be killed, and indirectly,

through habituation to humans, food conditioning,

and other possible risks.

Fundamental Goal 6: Achieve polar bear conserva-

tion while minimizing restrictions to other activities

within the range of the polar bear, including

economic development.

Local, regional, state, national, and global communi-

ties beneﬁt from human activities in the Arctic,

including tourism, recreation, oil and gas develop-

ment, mining, shipping, and scientiﬁc research.

In some cases, these activities may be compatible

with polar bear conservation; in others, there may

be conﬂicts. Finding strategies here in the United

States that allow both would beneﬁt multiple

stakeholders. This goal reﬂects objectives in the

administration’s “National Strategy for the Arctic

Region” (White House 2013a), which calls on United

States federal agencies to use integrated Arctic

management to balance economic development,

environmental protection, and cultural values.

In the following three sections (organized by the

MMPA, ESA, and other motivations, respectively),

the Fundamental Goals are expressed as quantita-

tive measures; for the goals related to the MMPA

and ESA, criteria associated with conservation

and recovery are provided. Where appropriate,

these fundamental criteria are further described

with stepped-down demographic and threats-based

criteria (Table 1).

16 Polar Bear Conservation Management Plan

III. Management Goals and Criteria

MMPA Conservation ESA Recovery Other Fundamental Goals

Fundamental Criteria & Performance Metrics

Conservation Criterion 1: The health

and stability of the marine ecosystem,

as evidenced by its capacity to support

polar bears, are maintained, and each

subpopulation of polar bears is maintained

as a signiﬁcant functioning element of that

ecosystem. (FG3)

AND

Conservation Criterion 2: Each

subpopulation is managed so that its

population size is above the maximum

net productivity level relative to carrying

capacity. (FG3)

Recovery Criterion 1: The

worldwide probability of persistence

is at least 95% over 100 years. (FG1)

AND

Recovery Criterion 2: The

probability of persistence in each

recovery unit (ecoregion) is at least

90% over 100 years. (FG2)

FG4: Cumulative take (all human-caused

removals) level over the next 50 years for

each subpopulation that includes parts of

Alaska.

FG5: Number of human-bear conﬂicts in

Alaska that result in injury or death to

humans or bears.

FG6: Economic impacts of polar bear

management actions, including direct and

indirect expenses, and lost or foregone

opportunities.

Demographic Criteria

MMPA Demographic Criterion 1: The

intrinsic growth rate of each subpopulation

is above, and is expected to remain above,

a minimum level that indicates the health of

the marine ecosystem is not impaired; and

the carrying capacity in each subpopulation

is above, and is expected to remain above,

70% of mean historical carrying capacity,

indicating that the stability of the marine

ecosystem is not impaired.

AND

MMPA Demographic Criterion 2:

Total human-caused removals in each

subpopulation do not exceed a rate h (relative

to the subpopulation size) that maintains

the subpopulation above its maximum net

productivity level relative to carrying capacity.

ESA Demographic Criterion 1:

The mean adult female survival

rate (at a density corresponding to

maximum net productivity level and in

the absence of direct human-caused

removals) in each recovery unit is at

least 93–96%, both currently and as

projected over the next 100 years.

AND

ESA Demographic Criterion 2: The

ratio of yearlings to adult females (at

a density corresponding to maximum

net productivity level) in each

recovery unit is at least 0.1–0.3, both

currently and as projected over the

next 100 years.

AND

ESA Demographic Criterion 3: The

carrying capacity, distribution, and

connectivity in each recovery unit,

both currently and as projected over

the next 100 years, are such that the

probability of persistence over 100

years is at least 90%.

AND

Continued

Table 1. Three-tier framework for MMPA conservation criteria and ESA recovery criteria; and performance metrics

for the remaining Fundamental Goals. The criteria are arranged in three tiers: fundamental (directly related to the

fundamental goals); demographic (stepped-down to the level of population demographic rates); and threats-based

(stepped-down further to the level of threats). For the fundamental goals (FG) not directly linked to MMPA or ESA,

performance metrics are described, without additional tiers or performance thresholds.

Polar Bear Conservation Management Plan 17

III. Management Goals and Criteria

MMPA Conservation ESA Recovery Other Fundamental Goals

ESA Demographic Criterion 4:

Total direct human-caused removals

in each recovery unit do not exceed a

rate h (relative to the population size

in the recovery unit) that maintains

the population above its maximum

net productivity level relative to

carrying capacity.

Threats-based Criteria

Sea ice: In each recovery unit, either

(a) the average ice-free period is

expected not to exceed 4 months

over the next 100 years based on

model projections using the best

available climate science, or (b) the

average ice-free period is expected to

stabilize at longer than 4 months over

the next 100 years based on model

predictions using the best available

climate science, and there is evidence

that polar bears in that recovery unit

can meet ESA Demographic Criteria

1, 2, and 3 under that longer ice-free

period.

AND

Human-caused removals: For

each recovery unit, the total level

of direct, lethal removals of polar

bears by humans, in conjunction with

other factors, does not reduce the

probability of persistence below 90%

over 100 years.

Table 1. Continued.

USFWS

18 Polar Bear Conservation Management Plan

III. Management Goals and Criteria

B. Conservation Criteria under the Marine Mammal Protection Act

Conservation plans are developed for depleted

species or stocks under the MMPA. “Each plan

shall have the purpose of conserving and restoring

the species or stock to its optimum sustainable

population. The Secretary shall model such plans

on recovery plans required under section 4(f) of

the Endangered Species Act of 1973” (16 USC

§1383b(b)(2)). Species or stocks of marine mammals

are designated as “depleted” in one of 3 ways:

because they fall below the optimum sustainable

population (OSP) level, as determined by the federal

government or by a state to whom authority has

been transferred; or because they are listed as

endangered or threatened under the ESA. In this

case, to no longer be considered depleted, polar

bears would have to be delisted under the ESA.

(The ESA recovery criteria are covered later; this

section considers only the MMPA criteria.) This

Plan describes MMPA conservation criteria at two

levels: fundamental and demographic (Table 1).

These criteria are nested: the demographic criteria

are derived from the fundamental criteria using the

best scientiﬁc information available at the time of

assessment.

MMPA fundamental criteria

Fundamental Goals 1, 2, and 3 are tied to the

conservation standards of the MMPA. Here, those

Goals are translated into speciﬁc criteria. At the

fundamental level, the goals for conservation of

polar bears under the MMPA are achieved when

both of the following criteria are met:

MMPA Conservation Criterion 1: The health

and stability of the marine ecosystem, as

evidenced by its capacity to support polar

bears, are maintained, and each subpopulation

of polar bears is maintained as a signiﬁcant

functioning element of that ecosystem.

MMPA Conservation Criterion 2: Each

subpopulation is managed so that its popula-

tion size is above the maximum net productiv-

ity level relative to carrying capacity.

The MMPA criteria apply both to the worldwide

population and to the individual subpopulations. The

depleted entity is the worldwide population of polar

bears, because the depleted status under the MMPA

was due to the listing of the species under the ESA.

Thus the criteria apply to the species as a whole. To

meet the criteria worldwide, it is sufﬁcient to meet

them in each stock. The two Alaskan polar bear

subpopulations (Southern Beaufort Sea, Chukchi

Sea) have been identiﬁed as “stocks” under the

MMPA (74 FR 69139). This Plan further assumes

that all 19 of the polar bear subpopulations qualify

as stocks under the MMPA. The management focus

of this Plan is the United States’ contribution to

polar bear conservation, so the conservation actions

described below focus primarily on the two subpopu-

lations found in United States territory.

Basis for the MMPA fundamental criteria

In the MMPA, Congress found that stocks should

not be permitted to diminish below their OSP level.

The MMPA deﬁnes OSP as “the number of animals

which will result in the maximum productivity of

the population or the species, keeping in mind the

carrying capacity of the habitat and the health of

the ecosystem of which they form a constituent

element” (16 USC §1362(9)). One of the challenges

in interpreting OSP for polar bears is the expecta-

tion that both the carrying capacity and the intrinsic

growth rate of subpopulations may change over time

due to anthropogenic forces, namely climate change.

We have addressed that expectation by adopting

two MMPA criteria in this Plan: one focused on

maintaining the carrying capacity of the habitat

and the health of the ecosystem; and one focused

on managing lethal removals to maintain each

subpopulation above its maximum net productivity

level. These constituent elements in the deﬁnition of

OSP are not separable; to meet OSP, both elements

need to be met.

We considered two possible ways to keep “in mind

the carrying capacity of the habitat and the health

of the ecosystem” when deﬁning OSP: one approach

is to adopt a single standard that combines the

concepts of maximum net productivity level and

carrying capacity into one criterion; the other

approach is to adopt two standards that specify

criteria for the two elements separately. Under the

ﬁrst approach, Maximum Net Productivity Level

(MNPL) would be deﬁned relative to a historical,

undisturbed carrying capacity and health of the

ecosystem; thus maintenance of carrying capacity

and management of removals are achieved under

a single criterion. Under the second approach,

maximum net productivity level (mnpl) would be

deﬁned relative to the current carrying capac-

ity, and a separate (but not separable) criterion

would be established for maintenance of carrying

capacity and health of the ecosystem. We use the

abbreviations MNPL and mnpl to refer to the

one- and two-standard approaches to interpreting

OSP, respectively. Both of these may be reasonable

interpretations of the intent of Congress, with the

choice of interpretation being made to best achieve

conservation in the context of a particular species.

We believe the unique setting of polar bear conser-

vation calls for use of the second approach. First,

the primary threat to polar bears is loss of sea-ice

habitat brought about by climate change and a

corresponding loss of carrying capacity and ecosys-

Polar Bear Conservation Management Plan 19

III. Management Goals and Criteria

tem health. Thus, a criterion that deals speciﬁcally

with carrying capacity and ecosystem health allows

us to focus on the primary threat. Second, polar

bears are legally hunted in the United States for

subsistence purposes, and are occasionally legally

killed in defense of human life. The management of

such take is also important for the conservation of

polar bears, so a criterion that speciﬁcally addresses

such take is valuable. The one-standard approach

does not separate the effects of habitat change

from the effects of removals, and does not provide a

standard that can be used to directly manage take,

so it does not serve to advance the conservation

of polar bears. In this Plan, because of the unique

circumstances of polar bears, we follow the two-

standard approach to interpreting OSP.

Health and stability of the marine ecosystem. The

ﬁrst criterion addresses the degree to which it is

acceptable for the marine ecosystem to change as

a result of anthropogenic causes (as reﬂected in

changes in the carrying capacity or the health of

the ecosystem). It is clear that signiﬁcant declines

in these attributes are not acceptable under the

MMPA. In the “ﬁndings and declaration of policy”

section of the MMPA, Congress indicates that “the

primary objective of [marine mammal] management

should be to maintain the health and stability of

the marine ecosystem” (16 USC §1361(6)). Another

purpose of the law is to ensure that stocks do not

“diminish beyond the point at which they cease to be

a signiﬁcant functioning element in the ecosystem of

which they are a part” (16 USC §1361(2)). Further,

Congress directed that the “carrying capacity of the

habitat and the health of the ecosystem” be kept in

mind when determining OSP (16 USC §1362(9)).

In the extreme, if polar bears are extirpated from

large parts of their range because of loss of sea ice,

then they surely will have ceased to be a signiﬁcant

functioning element of the ecosystem; indeed, the

“health and stability of the marine ecosystem”

will have been changed. The health and stability

of the marine ecosystem likely can, however, be

maintained, and polar bears likely can remain a

signiﬁcant functioning element of the ecosystem

without remaining at historical numbers, provided

efforts are made “to protect essential habitats…

from the adverse effects of man’s actions” (16 USC

§1361(2)). We propose to evaluate the health of the

marine ecosystem using the intrinsic growth rate for

polar bears, and the stability of the marine ecosys-

tem using the carrying capacity for polar bears. If

the health of the ecosystem declines, the survival

and reproductive rates of polar bears, and hence

their intrinsic rate of population growth, will decline.

If the ability of the ecosystem to support polar bears

declines, the carrying capacity will decline.

Congress did not provide any further explanation

of the term “signiﬁcant functioning element in the

ecosystem,” there is not any legislative history

associated with this term, and the case law is

limited. Further, we are not aware of any regulatory

action or conservation plans by either the USFWS

or NMFS that have deﬁned or incorporated this

term. Nor is there guidance on interpreting “health

and stability of the marine ecosystem.” Neverthe-

less, we believe these purposes of the MMPA are

particularly relevant for polar bear conservation

because of the nature of the long-term threats, and

thus, we are applying these terms in this plan.

Polar bears play a unique function in the Arctic

ecosystem as a top predator. In considering the

ecological function of other top predators (grizzly

bears and wolves) in their ecosystems, Pyare and

Berger (2003) argue that the ecological function of

these large carnivores is as important a measure

of status as their demographic prospects, because

“Research continues to demonstrate that these

terrestrial carnivores, perhaps more so than most

other threatened or endangered species, have

far-reaching consequences for their ecosystems.”

Similar arguments can be made for the highly

inﬂuential role that sea otters (Enhydra lutris) have

in maintaining the marine ecosystems they occupy

(Estes and Duggins 1995; USFWS 1994, 2013).

The effects of the marine ecosystem on polar bear

populations and the effects of polar bear populations

on the marine ecosystem are both important consid-

erations in evaluating the health and stability of the

ecosystem, and whether polar bears are a signiﬁcant

functioning element of the ecosystem. This broad

understanding of MMPA Conservation Criterion 1

is important in any future evaluation of the criteria

in this Plan. In the next section, we focus on intrinsic

growth rate and carrying capacity of the polar bear

population as indicators of the health and stability of

the marine ecosystem, respectively. They may not be

good indicators, but they are nevertheless indica-

tors, not direct measures of health and stability,

and the broader perspective of ecosystem function

should not be lost, especially at lower trophic levels.

The primary threat to polar bears, and the threat

most at odds with the intent of the MMPA, is the

expected long-term loss, through climate change, of

the ecosystem of which polar bears are a part. This

ﬁrst MMPA criterion, perhaps the highest and most

ambitious standard in this Plan, would likely require

substantial reduction in worldwide greenhouse gas

emissions as well as substantial reduction in the loss

of sea ice Arctic-wide.

Maximum net productivity level. The second

MMPA criterion addresses the extent to which it is

acceptable for lethal removals to reduce the size of

a polar bear subpopulation relative to its potential

size in the absence of such removals. This criterion

integrates the biological concepts of carrying capac-

ity, maximum net productivity level, intrinsic growth

20 Polar Bear Conservation Management Plan

III. Management Goals and Criteria

rate, sex- and age-composition of the population,

sex- and age-composition of lethal removals (includ-

ing subsistence harvest), and sustainable take. At

any point in time, the population size at which a

population is most productive is conditional on the

extent to which limiting resources are utilized. The

availability of limiting resources, which determine

the carrying capacity, can vary naturally or through

anthropogenic forces, and the maximum net produc-

tivity level (mnpl) will vary in proportion. Likewise,

the intrinsic growth rate can vary over time, as a

function of the health of the ecosystem, and the

intrinsic growth rate also affects the maximum

net productivity. Both of these considerations, the

possibly changing carrying capacity and the possibly

changing intrinsic rate of growth, need to be kept in

mind when evaluating the number of removals that

will maintain a population above its maximum net

productivity level. In long-lived mammal populations

in which removals are unbiased with regard to

age or sex, maximum net productivity occurs at

some population size greater than 50% of carrying

capacity; for polar bears, demographic analysis

suggests that this level occurs at approximately 70%

of carrying capacity (Regehr et al. 2015).

MMPA demographic criteria

Health and stability of the marine ecosystem. As

suggested above, the health and stability of the

Arctic marine ecosystem, respectively, are reﬂected

in the intrinsic rate of growth and the carrying

capacity of polar bear populations. The intent of the

ﬁrst MMPA criterion is to ensure that polar bears

remain a functioning element of the ecosystems

associated with each subpopulation and that the

intrinsic growth rate and carrying capacity do

not decline to the point that this function is lost.

Although this does not require maintaining the

historical levels of intrinsic growth rate and carrying

capacity, it will require substantial and successful

efforts to limit the anticipated losses from climate

change, so that polar bears and their ecosystem

remain healthy and stable.

MMPA Demographic Criterion 1: The intrinsic

growth rate of each subpopulation is above,

and is expected to remain above, a minimum

level that indicates the health of the marine

ecosystem is not impaired; and the carrying

capacity in each subpopulation is above, and

is expected to remain above, 70% of mean

historical carrying capacity, indicating that

the stability of the marine ecosystem is not

impaired.

The MMPA provides clear technical guidance on

how to determine the tolerable reduction in popula-

tion size as a result of human-caused removals (see

“Maximum net productivity level,” below), but it

does not provide similar guidance for reduction

as a result of habitat loss or other threats besides

human-caused removals. Nevertheless, with regard

to a loss of carrying capacity, we reason that the

reduction of carrying capacity to 70% of its histori-

cal level would produce an impact to a polar bear

population of similar magnitude to human-caused

removals at the level that achieves mnpl.

There is not a parallel way to determine a threshold

for the intrinsic growth rate, because reductions in

growth rate affect populations in a different manner

than reductions in carrying capacity or population

size. Thus, at this time, we cannot make the policy

interpretation needed to establish the ﬁrst half of

MMPA Demographic Criterion 1.

The intrinsic growth rate and carrying capac-

ity may change independently. For instance, the

carrying capacity for a subpopulation might decline

substantially, but the intrinsic growth rate of the

subpopulation might remain satisfactory. For MMPA

Demographic Criterion 1 to be met, both conditions

need to be met.

For polar bears, we propose using the reference

period 1953–1972 for determinations of “historical”

carrying capacity. At the time of the enactment of

the MMPA, Arctic marine ecosystems were believed

to be intact, so the period preceding 1972 serves

as a time when the “health and stability of the

marine ecosystem” in the Arctic were at historical

levels. The period of measurement record for Arctic

sea-ice extent begins in 1953; the September sea-ice

extent over the period 1953–1972 showed variation

around a stable mean (Fig. 4). Thus, to the extent

that scientists and managers seek to determine the

historical carrying capacity for a given subpopula-

tion, we propose that the period 1953–1972 is a

relevant reference.

The estimation of carrying capacity, whether current

or historical, is difﬁcult, because it can rarely be

observed directly. Rather it needs to be inferred

from magnitude and trends in population size and

habitat metrics, taking into account the levels of

human-caused removals. There are a variety of

methods that could be used for this estimation task,

and development of these for polar bear subpopula-

tions is needed. The possible methods include: (1)

establishing a relationship between current carrying

capacity and some relevant habitat metric for which

we have measurements in the reference period, and

back-extrapolating; (2) estimating carrying capacity

over a time series of abundance or other life-history

measures, using hierarchical population modeling

techniques, and inferring the historical carrying

capacity; or (3) assuming carrying capacity has

remained stable until recently, inferring the recent

carrying capacity from estimates of population size

and human-caused removal rates, and using that as

an estimate of historical carrying capacity. The ﬁrst

Polar Bear Conservation Management Plan 21

III. Management Goals and Criteria

two methods will be quite difﬁcult, the third method

is more manageable but the assumptions may be

more difﬁcult to justify for some subpopulations.

As noted above, we are treating polar bear carrying

capacity as an indicator of the stability of the marine

ecosystem. For practical purposes, assessment of

individual subpopulations could be undertaken with

other indicators (e.g., sea ice).

Regarding polar bears as a functioning element of

the ecosystem, complex methods to assess the func-

tional diversity of ecosystems have been proposed

(e.g., Petchey and Gaston 2002), but the application

of such methods to a changing Arctic involving

polar bears would likely be difﬁcult and insensitive

to meaningful near-term ecological changes. Thus,

at this time, we do not have enough information to

propose more detailed measures, and associated

thresholds, to directly assess the functional role

of polar bears in their ecosystem. Development of

such measures is an important task under this Plan.

Thoughtful development of approaches based on the

particular roles polar bears play in the ecosystem

could help with assessment as this Plan is updated in

the future.

Maximum net productivity level. At the fundamen-

tal level, MMPA Conservation Criterion 2 requires

that each polar bear subpopulation size is above

its mnpl; at this time, we estimate this occurs at

approximately 70% of the maximum number of

polar bears the environment can support on average

(Regehr et al. 2015). Estimating the subpopulation

size at carrying capacity, and by extension the

mnpl, is challenging because environmental factors

limiting population growth vary with time and are

difﬁcult to measure. Nonetheless, it is possible to

manage wildlife populations in a way that satisﬁes

the fundamental criterion if removal levels are based

on an estimate of current population size and a

harvest rate h that is designed to maintain a popula-

tion above its mnpl with some acceptable level of

probability. Thus, the MMPA demographic criteria

for maintaining a subpopulation above mnpl can be

stated using this more proximate metric:

MMPA Demographic Criterion 2: Total

human-caused removals in each subpopulation

do not exceed a rate h (relative to the subpopu-

lation size) that maintains the subpopulation

above its maximum net productivity level

relative to carrying capacity.

The removal rate that achieves MMPA Demo-

graphic Criterion 2, h, depends on the underlying

demographic rates for the subpopulation, the sex

and age composition of the subpopulation, as well as

the sex and age composition of removals. A valuable

reference point is the removal rate, h

mnpl

, that

achieves mnpl at equilibrium when removals are in

direct proportion to the sex and age composition of

the subpopulation (i.e., when removals do not select

for certain sex or age classes of animals). The value

of h

mnpl

is derived based on population dynamics

theory, general life history parameters for the

species, and subpopulation-speciﬁc demographic

information (Runge et al. 2009). For polar bears,

mnpl

is likely 79–84% of the intrinsic population

growth rate (Regehr et al. 2015). The theoretical

Figure 4. Arctic sea-ice extent in September, 1953–2015, in millions of square

kilometers. The solid and dashed lines show the mean extent for the period

1953–1972. We propose that this reference period is suitable for evaluating “histori-

cal” conditions of polar bears in the context of the MMPA.

1

1950 1960 1970 1980 1990 2000 2010 2020

September

sea‐iceextent(10

)

Year

MMPA

referenceperiod

22 Polar Bear Conservation Management Plan

III. Management Goals and Criteria

maximum population growth rate for the species is

approximately 6–14% (Taylor et al. 2009, Regehr

et al. 2010) but may be less if habitat loss or other

factors affect subpopulations negatively through

density-independent effects.

These interpretations of mnpl represent the views

of USFWS for the purpose of conserving polar

bears. This approach does not necessarily preclude

other approaches to determining mnpl or MNPL in

other conservation plans.

USFWS

Polar Bear Conservation Management Plan 23

III. Management Goals and Criteria

C. Recovery Criteria under the Endangered Species Act

The ESA requires a recovery plan to incorporate,

to the maximum extent practicable, “objective,

measurable criteria which, when met, would result

in a determination, in accordance with the provisions

of this section, that the species be removed from

the list [of endangered and threatened wildlife]…”

(16 USC §1533(f)(1)(B)(ii)). Following a three-tier

framework, this Plan describes recovery criteria at

three levels (Table 1): fundamental, demographic,

and threats-based. These criteria are meant to be

compatible: the demographic and threats-based

criteria are derived from the fundamental criteria,

using the best available scientiﬁc information avail-

able at the time of assessment. To achieve recovery,

the criteria at all three levels need to be met.

ESA fundamental criteria

The aspects of Fundamental Goals 1 and 2 that

refer to securing long-term persistence are tied

to recovery under the ESA. Here, those Goals are

translated into quantitative measures with threshold

criteria associated with recovery. At the fundamen-

tal level, both of the following criteria need to be met

to achieve recovery of polar bears:

Recovery Criterion 1: the worldwide probabil-

ity of persistence is at least 95% over 100 years.

Recovery Criterion 2: the probability of

persistence in each recovery unit (ecoregion) is

at least 90% over 100 years.

Basis for the ESA recovery criteria

The conservation of species is a key purpose of the

ESA, and the Act deﬁnes conservation in terms of

bringing species to the point that the Act’s provi-

sions are no longer necessary. The ESA does not

specify a numerical standard for determining when

a species is threatened or endangered, nor is there

a universal approach for making such determina-

tions. Although the ESA does not use terms such

as “probability” or “persistence,” the deﬁnitions of

endangered (“in danger of extinction throughout

all or a signiﬁcant portion of its range,” 16 USC

§1532(6)) and threatened suggest that the risk of

extinction is a primary concern. Thus, many scholars

of the ESA have identiﬁed the fundamental goal of

recovery as reducing the probability of extinction to

an acceptable level, stated equivalently as keeping

the probability of persistence above some threshold

(e.g., Doremus 1997, Gregory et al. 2013, Ralls et al.

2002, Regan et al. 2013, Seney et al. 2013). In listing

decisions and recovery plans where probability of

persistence has been used, the threshold between

“threatened” and “listing is not warranted” has been

characterized by a number of values, roughly rang-

ing between 90% and 99% probability of persistence

over a century (e.g., USFWS 1995, 2002; see also

DeMaster et al. 2004, Regan et al. 2013). In this

Plan, we adopt a desired probability of persistence

of 95% over a century for the listed entity; although

an even higher probability is the aspiration of all the

management partners, the question is the degree of

persistence at which the species no longer needs the

protections of the ESA. If the probability of persis-

tence is greater than 95% over the next 100 years,

then the risk of extinction is low enough and distant

enough that it is not likely to become in danger of

extinction in the foreseeable future.

This Plan uses probability of persistence to express

the fundamental recovery criteria for polar bears.

Given the nature of the primary threat to polar

bears–loss of sea ice due to changes in climate–as

well as the speed at which the climate would respond

to changes in atmospheric levels of greenhouse

gases, 100 years is a time period over which we

could see movement towards recovery or towards

extinction depending on worldwide efforts to curtail

emissions. The ﬁrst criterion focuses on the listed

entity (the worldwide population of polar bears) and

indicates this particular measure of recovery will be

achieved when the probability of persistence over

100 years is at least 95%.

Beyond this Plan’s ﬁrst criterion for survival of the

listed entity, the second criterion further speciﬁes

that a signiﬁcant portion of the diversity of the

species, as represented by the ecoregions, must also

be conserved, in order to promote recovery through

representation and redundancy. The risk tolerance

for extinction for each of the individual ecoregions

(10%) is higher than for the species as a whole (5%)

because the ecoregions are only components of

the listed entity. It’s worth noting that if the prob-

abilities of persistence in the four recovery units

are independent and each 90%, the probability of

persistence of the listed entity is 99.99%. Although

the assumption of independence is unlikely, this

calculation suggests that Recovery Criterion 2 may

be considerably more protective than Recovery

Criterion 1.

The purposes of an intermediate scale (i.e., recovery

unit) in Recovery Criterion 2 include (1) to preserve

diversity among polar bears—diversity that is at the

heart of ESA protection and important to species

viability; (2) to acknowledge that polar bears in

different regions may experience different threats

and conditions and exhibit different responses to

those, which may warrant different conservation

approaches now or in the future; and (3) to provide

redundancy, and hence increase the survival of the

species, by conserving polar bears in more than one

region. In order to remove the danger of extinction

“within the foreseeable future throughout all or a

24 Polar Bear Conservation Management Plan

III. Management Goals and Criteria

signiﬁcant portion of the range” (16 USC §1532(20)),

a high probability of persistence in each of the

recovery units is needed.

Ecoregions. The best available science suggests that

the “ecoregions” proposed by Amstrup et al. (2008)

capture broad patterns in genetic and life-history

variation for the species. Furthermore, ecoregions

were based on observed and forecasted changes in

sea-ice habitat and thus capture anticipated varia-

tion in the primary long-term threat. We recognize

that further research, building on an existing body

of work (Spalding et al. 2007, Thiemann et al. 2008),

is needed on details of the genetic, behavioral,

ecological, and threats-based factors that distinguish

spatial groupings of polar bears.

Recovery units. In ESA recovery planning, a

“recovery unit” is “a special unit of the listed entity

that is geographically or otherwise identiﬁable and

is essential to the recovery of the entire listed entity,

i.e., recovery units are individually necessary to

conserve genetic robustness, demographic robust-

ness, important life history stages, or some other

feature necessary for long-term sustainability of the

entire listed entity.” Furthermore, “establishment

of recovery units can be a useful recovery tool,

especially for species occurring across wide ranges

with multiple populations or varying ecological

pressures in different parts of their range.” (NMFS

and USFWS 2010, section 5.1.7.1). Because recovery

units are “essential to the recovery of the entire

listed entity,” the criteria must be met in all recovery

units in order for recovery to be achieved and for

delisting to be recommended.

Ecoregions as recovery units. Polar bears occur

in 19 subpopulations throughout the circumpolar

Arctic; one of the largest ranges for an extant large

carnivore. Within this range the species exhibits

variation in genetics, behavior, and life-history

strategies. Within the timeframe considered by

this Plan, polar bears are expected to experience

different pressures resulting in potentially high

probabilities of extirpation (e.g., in some parts of

the Polar Basin Divergent Ecoregion) to moderate

probabilities of persistence (e.g., in the Archipelago

Ecoregion) (Amstrup et al. 2008, 2010). National and

local management regimes, including collaborative

management across jurisdictions, also vary across

the species’ range.

This Plan uses the 4 ecoregions as recovery units

because this approach provides a reasonable

representation of important variation for both polar

bears and the threats they face. This approach helps

augment the persistence of polar bears as a whole

by conserving them in multiple regions and allowing

conservation actions to be tailored to the most press-

ing issues in each region. Consequently, persistence

of polar bears in all 4 ecoregions is necessary to the

recovery of the listed entity.

Any intermediate spatial-scale grouping of polar

bears, if meant to apply over a long time scale, will

reﬂect a number of assumptions and imperfections,

due to scientiﬁc uncertainty and the dynamic nature

of climate change and its effects on ecosystems.

Using the 4 ecoregions deﬁned by Amstrup et

al. (2008) as recovery units represents current

knowledge of the ecological diversity of polar bears

and their future response to climate change. But

because the current information is imperfect, it

may be important to conserve an even ﬁner-scale

representation of current polar bear diversity in the

near term, while seeking to improve our scientiﬁc

understanding of the distribution of important polar

bear ecological diversity. As understanding of polar

bears, climate change effects, and other relevant

information increases, the delineation of the recov-

ery units should be reviewed and, if appropriate,

modiﬁed, to reﬂect the best available science.

Deﬁnition of “persistence.” In the two ESA

recovery criteria (above), we deﬁne “persistence” as

maintaining the population size in a recovery unit

(or worldwide) at greater than 15% of the population

size of the unit at the time of listing or greater than

100 individuals, whichever is larger. If, at any point

during a 100-yr forecast, the projected population

drops below this threshold, it is considered not to

have persisted. This threshold is not a desired popu-

lation target. Rather, by focusing on the probability

of persisting above the threshold, the criteria repre-

sent the risk tolerance at which we could reasonably

conclude that polar bears are no longer threatened.

To achieve recovery, the population size needs to

be sufﬁciently larger than the threshold and the

threats sufﬁciently reduced to ensure that the risk

of dropping below the threshold is small (i.e., less

than 10% over 100 years). (The distinction between

“conservation and survival”, in the manner those

terms are used in Section 4(f) of the ESA [16 USC

§1533(f)], is useful here. The persistence threshold

represents the point at which the population is no

longer surviving. Recovery, that is, “conservation”,

is a higher bar than merely surviving.) For large

mammals, the effects of demographic stochasticity

become prominent at population sizes less than 100

(Morris and Doak 2002, Wieglus 2001). For polar

bears, mating success may decline when subpopula-

tion density falls below a fraction of present-day

values (i.e., there might be an Allee effect), but this

point depends on the sex- and age-structure of the

population, as well as the population-speciﬁc demo-

graphic parameters (Molnár et al. 2008, 2014). As

the geographic scope expands from subpopulation to

recovery unit to species, the Allee effect threshold

may occur at lower fractions of the original popula-

tion size, and will depend on the geographic distribu-

tion and connectivity of bears within the unit. The

Polar Bear Conservation Management Plan 25

III. Management Goals and Criteria

15% threshold is a placeholder based on available

information at a subpopulation level (Molnár et al.

2008), and should be re-evaluated on a case-by-case

basis and as new information arises. The 2015

update to the IUCN Red List Assessment for

polar bears (Wiig et al. 2015) summarizes the best

available information about the population size in

each ecoregion; although the underlying data span

a number of years, we view this as the best estimate

of the population sizes around the time of listing

(Table 2). The 15% threshold exceeds 100 animals

in all four ecoregions, thus, the 15% threshold is the

operational criterion for persistence (recognizing

that this is the threshold for survival, not recovery).

ESA demographic criteria

The demographic recovery criteria are derived from

the fundamental recovery criteria, but are stated

in more proximate measures of population status.

The spatial scale of the demographic criteria is the

recovery unit. Although the listed entity is polar

bears throughout their range, Recovery Criterion 2

identiﬁes the ecoregions as recovery units. To meet

the ESA recovery criteria, the fundamental and

demographic recovery criteria need to be met for

each recovery unit. Thus, the recovery criteria can

be focused at the recovery unit level. Recognizing

that the United States only has management

jurisdiction in parts of one recovery unit (the Polar

Basin Divergent Ecoregion), that unit is the main

focus of our recovery efforts, but assessment of the

recovery of the listed entity needs to consider all of

the recovery units.

The demographic criteria focus on three measures of

population status: survival rate, reproductive rate,

and carrying capacity. Recovery at the recovery-unit

(ecoregion) scale would be achieved when all four of

the following criteria are met:

ESA Demographic Criterion 1: The mean adult

female survival rate (at a density correspond-

ing to maximum net productivity level and in

the absence of direct human-caused removals)

in each recovery unit is at least 93–96%, both

currently and as projected over the next 100

years.

ESA Demographic Criterion 2: The ratio

of yearlings to adult females (at a density

corresponding to maximum net productivity

level) in each recovery unit is at least 0.1–0.3,

both currently and as projected over the next

100 years.

ESA Demographic Criterion 3: The carrying

capacity, distribution, and connectivity in each

recovery unit, both currently and as projected

over the next 100 years, are such that the

probability of persistence over 100 years is at

least 90%.

ESA Demographic Criterion 4: Total direct

human-caused removals in each recovery unit

do not exceed a rate h (relative to the popula-

tion size in the recovery unit) that maintains

the population above its maximum net produc-

tivity level relative to carrying capacity.

Although Fundamental Recovery Criterion 2 (90%

probability of persistence at the recovery unit level)

is the standard for assessment, these demographic

criteria use population metrics to represent an

equivalent condition, given the current state of

knowledge. These are, of course, a simpliﬁcation of

all the population dynamics that give rise to a high

probability of persistence, but these are based on

the most inﬂuential drivers of persistence. Based on

life-history theory, adult female survival exerts the

largest inﬂuence on population growth rate, which is,

in turn, a strong driver of resilience and persistence.

The ratio of yearlings to adult females incorporates

a number of aspects of the recruitment process:

breeding probability, litter size, and cub-of-the-year

survival. Populations need recruitment to persist,

and for some long-lived species, recruitment rates

vary more than adult survival rates and drive most

of the observed variation in population growth rate.

Finally, the probability of persistence is related to

population size and hence carrying capacity, because

the risk associated with annual variation and chance

events is magniﬁed at smaller population sizes.

The ﬁrst three demographic recovery criteria are

not independent. The speciﬁc threshold required

for any one depends on the thresholds required for

the other two (Fig. 5). For example, if the carrying

Archipelago Convergent Divergent Seasonal Total

Population size

4945 3004 9751 8785 26485

(2015) estimate

(3900–6000) (800–5200) (5800–13700) (7800–9700) (22000–31000)

15% threshold

742 451 1463 1318 3973

Table 2. Estimates of population size (with 95% conﬁdence limits) and persistence ﬂoor for each

ecoregion. The estimates and conﬁdence limits for the ecoregions were calculated by the same

methods Wiig et al. (2015) used for the global population.

26 Polar Bear Conservation Management Plan

III. Management Goals and Criteria

capacity were only expected to remain above 500

and the recruitment rate (ratio of yearlings to adult

females) were expected to remain above 0.2, the

adult female survival rate would need to remain

above 0.95 (assuming the rate of human-caused

removals is less than h). Because many possible

combinations of these three parameters can produce

the same probability of persistence, the criteria are

described as ranges, but to achieve recovery, the

combination of demographic criteria needs to meet

the standards for ESA Fundamental Criterion 2

(90% probability of persistence for the recovery

unit).

The third demographic criterion (carrying

capacity, distribution, and connectivity needed to

meet ESA Fundamental Criterion 2) provides the

buffer that is needed to protect the population

in a recovery unit from dropping below the level

at which small-population dynamics take over. A

speciﬁc threshold for carrying capacity cannot be

determined at this time because, as noted earlier,

there is uncertainty about how to scale potential

Allee effects from the subpopulation level up to

the ecoregion level. Given that future reductions

in population size due to habitat loss will likely be

accompanied by contraction of the geographic range

within each ecoregion, it is likely that Allee effects

and other negative small-population effects would

not manifest until population size is considerably

lower than 15% of the population size at the time of

listing. At the ecoregion level, the population size

at which Allee effects appear may also depend on

the distribution and connectivity of subpopulations

within the ecoregion. If the subpopulations in an

ecoregion were well connected, a carrying capacity

of 500–1000 animals, in combinations with the other

demographic criteria, may be enough to assure

the desired level of persistence (Fig. 5, Regehr et

al. 2015), but in other situations, a higher carrying

capacity might be needed. Thus, we cannot deter-

mine the speciﬁc thresholds for carrying capacity,

distribution, and connectivity at this time, because

we lack an understanding of how those factors will

interact to provide the buffer necessary to assure

a high probability of persistence. But we do know

that the buffer provided by the third demographic

criterion is needed; the other demographic criteria

alone cannot assure recovery.

The fourth demographic criterion speciﬁes an

upper bound on the rate of direct human-caused

removals, and the other demographic criteria have

been calculated assuming that rate. (Direct human-

caused removals are those that occur as a direct

result of human action, such as subsistence hunting,

Figure 5. Values of three ESA demographic criteria that provide a 90% probability of persistence (Regehr et al.

2015). The combination of survival (x-axis), recruitment (y-axis), and carrying capacity (contours) needs to be above

and to the right of the corresponding contour to provide the required probability of persistence. There are trade-offs

among these criteria, such that if any of these measures are quite high, the standard for the others can be lower. For

example, if the recruitment rate (yearling to adult female ratio) was expected to remain above 0.3 and the carrying

capacity was expected to remain above 1000, the adult female survival rate would only need to be 0.93 to achieve

recovery. In this graph, the rate of total human-caused removals is assumed to be at the maximum rate allowable

under MMPA Demographic Criterion 2.

Polar Bear Conservation Management Plan 27

III. Management Goals and Criteria

defense-of-life, and incidental take. Indirect remov-

als, such as those that occur as a result of habitat

degradation, are captured either in the survival rate

or the carrying capacity. This distinction is largely

in deference to the ability to monitor direct, but not

indirect, removals.) If the rate of human-caused

removals is less than this upper bound, the demands

for the other demographic criteria can be reduced,

provided the persistence criterion is met. It is also

possible to meet ESA Fundamental Criterion 2

(90% probability of persistence over 100 years)

without meeting ESA Demographic Criterion 4

(human-caused removal rate less than h), but this

would require even higher survival and reproduc-

tive rates than speciﬁed by the second and third

demographic criteria (see discussion, below, of ESA

Threats-based Criterion 2). Thus, while the fourth

demographic criterion is not strictly necessary for

recovery, we have included it as a recovery criterion

because it reiterates MMPA Demographic Criterion

2, the combination of non-anthropogenic mortality

and anthropogenic mortality is critical, and the other

demographic criteria can only be set in the context

of the anthropogenic mortality.

There are three particular challenges in developing

and evaluating these demographic criteria: climate

change effects, density-dependence, and harvest.

First, sea-ice loss related to climate change is a

long-term threat that will present changing condi-

tions for ice-dependent Arctic species like the polar

bear. All of these demographic criteria are likely met

currently for the Polar Basin Divergent Ecoregion,

as well as for others; the concern is that they will

not continue to be met as climate-driven sea-ice

loss increases, which is why polar bears were listed.

Thus, the evaluation of the demographic criteria

needs to assess whether they will continue to be

met over the next 100 years. Second, survival and

recruitment (the ﬁrst two demographic criteria)

may be density-dependent, that is, they naturally

decrease as the population size approaches carrying

capacity. Thus, a threshold value for those rates is

meaningless unless it is associated with a particular

population density. Here, we have chosen to estab-

lish these criteria in reference to the mnpl, which is

the population size, relative to the carrying capacity

at a point in time, that produces the highest net

annual production, assuming removals are unbiased

with regard to age and sex. This is a particularly

practical reference point because for polar bear

populations that are managed to be near mnpl,

the observed survival and recruitment rates can

be compared directly to the criteria. Third, for any

populations that are subject to direct human-caused

removals, the survival rate will be the product of

both the survival rate in the absence of anthropo-

genic take and the survival rate associated with

those removals, taking into account the sex and age

composition of the population and of the removals.

The survival rate in Demographic Criterion 1 refers

to the survival rate in the absence of removals, and

hence encompasses non-anthropogenic mortality;

the total take rate in Demographic Criterion 4 refers

to anthropogenic mortality.

The demographic criteria listed above are stated

in terms of average values of the true underlying

rates, not annual rates. Annual variation around

these mean values is expected; the criteria require

that the mean values of those stochastic processes

be above the indicated thresholds. Using average

values assumes that potential future change in how

much the rates vary from year-to-year will not, in

itself, have a meaningful effect on persistence. Also

the demographic criteria were derived assuming

a perfect ability to estimate them; the empirical

precision needed has not yet been developed. If the

demographic rates are measured or forecast with

considerable error, then it is possible to think that

the criteria have been achieved when the true values

do not, in fact, meet the criteria or, vice versa, to

think that the criteria have not been achieved when,

in fact, they have. The risk due to sampling error

has not been directly incorporated into the interpre-

tation of these criteria, but that consideration should

be evaluated carefully whenever a population status

assessment is made, and could be incorporated into

a future revision of this Plan.

The estimation of annual and mean rates for three

of the four demographic parameters (survival,

recruitment, and take rates) can be conducted with

monitoring programs that are already in place in

several polar bear subpopulations, including the

Southern Beaufort Sea. These programs currently

involve the marking and recapturing of individual

bears over time. Note, however, that the existing

monitoring programs are focused at the subpopula-

tion level but the ESA demographic criteria are

focused at the recovery unit level; research will be

needed to understand how to make inference at the

recovery unit level from data at the subpopulation

level (Regehr et al. 2015). The estimation of the

fourth demographic parameter, carrying capacity,

is notoriously challenging, because the link between

habitat variables and population responses is often

poorly understood. Modern statistical methods

(known as “hierarchical models”) provide a way to

estimate “latent” parameters like carrying capacity,

by integrating survival, recruitment, harvest,

habitat, and population size data into a single

statistical framework (Royle and Dorazio 2008). If

such a statistical model is developed for polar bears,

it can then be linked to forecasts of the habitat

variables (Durner et al. 2009) to provide the current

and projected estimates of carrying capacity needed

for Demographic Criterion 3.

As noted above, these demographic criteria should

be subject to periodic revision as new information

becomes available to inform their derivation.

28 Polar Bear Conservation Management Plan

III. Management Goals and Criteria

Because of this, use of the demographic criteria is

not a substitute for development of a full population

viability analysis for evaluation of the fundamental

recovery criteria. Such development will allow both

reﬁnement of the demographic criteria as well as

direct evaluation of the fundamental criteria.

ESA threats-based criteria

The ESA threats-based recovery criteria are

derived from the fundamental and demographic

recovery criteria described above, but are stated

with regards to the threats to the species, so that

they correspond to the listing factors described in

the ESA (16 USC§1533(a)) and facilitate achieve-

ment of the demographic criteria. The listing rule

for polar bears identiﬁed one threat, loss of sea ice,

under Factor (A) “threatened destruction…of its

habitat.” The rule also acknowledged, under Factor

(D) “inadequacy of existing regulatory mechanisms,”

that “there are no known regulatory mechanisms

in place at the national or international level that

directly and effectively address the primary threat

to polar bears—the range-wide loss of sea-ice

habitat” (73 FR 28288). In what follows, we discuss

threats-based recovery criteria in 3 categories: those

threats that were identiﬁed in the listing rule and

are currently an impediment to recovery (sea-ice

loss); those potential threats that are not currently

an impediment to recovery, but could become

impediments before the threats in the ﬁrst category

are addressed; and those potential threats that

could become an issue in the future, but are of more

distant concern at this time. We develop threats-

based recovery criteria for the ﬁrst two categories,

but not the third, noting that future revisions of this

Plan will need to revisit the proximity and severity

of threats and potential threats in all categories.

As with the demographic recovery criteria, the scale

of the threats-based criteria is the recovery unit. To

meet the ESA recovery criteria, the demographic

and threats-based recovery criteria need to be met

for each recovery unit.

Sea ice and terrestrial habitat. The primary threat

to polar bears is loss of its sea-ice habitat, driven

by Arctic warming. In some subpopulations, the

physiological and demographic effects of longer

ice-free periods are already evident (Regehr et al.

2007, 2010; Rode et al. 2014; Bromaghin et al. 2015)

and polar bears already have exhibited behavioral

responses to longer ice-free periods, spending

more time on land during the summer (Fischbach

et al. 2007; Schliebe et al. 2008; Rode et al. 2015;

Atwood et al. 2016). Given the predicted increase

in ice-free periods, these behavioral changes are

anticipated to increase and are expected to lead to

an increase in population-level demographic effects

in the future. In the long term, recovery of polar

bears will require measures to address the loss of

sea ice (climate change mitigation); in the mid-term,

recovery may also require attention to conservation

of the terrestrial habitats polar bears use during the

ice-free months. While there could be some trade-off

among these efforts, such that greater terrestrial

conservation might allow for achieving recovery

of polar bears with lesser climate mitigation than

otherwise would be needed, the most critical aspect

is that polar bears are able to maintain adequate

access to prey resources. Both aspects of this threat

(sea ice and terrestrial habitat) are discussed below:

a speciﬁc criterion is offered for sea ice; develop-

ment of a criterion for terrestrial habitat will require

more research.

In three of the four recovery units (Polar Basin

Divergent, Polar Basin Convergent, Archipelago,

Fig. 2), the annual ice-free period has historically

been short and polar bears have had potential access

to seals nearly uninterrupted year-round. But for

one of the recovery units (Seasonal Ice, Fig. 2),

polar bears have historically coped with an ice-free

summer during which they had reduced access to

prey. There is empirical evidence that the potential

for fasting mortality may increase after 120 days

(Lunn and Stirling 1985; Molnár et al. 2010, 2014;

Robbins et al. 2012; Cherry et al. 2013), thus, we

assume that polar bears, given sufﬁcient access

to prey during other times of year, are capable

of persisting with an average ice-free period of 4

months or less. It is possible that polar bears can

persist with a longer ice-free period than 4 months,

or could do so if they made adaptations (e.g., altered

seasonal migration, alternative food sources). To

achieve recovery in a recovery unit, we would either

need to have evidence that the ice-free period was

going to remain 4 months or less, or evidence that

the ice-free period was going to stabilize at some-

thing longer than 4 months and that polar bears

were able to persist at that longer ice-free period.

ESA Threats-based Criterion 1 (sea ice): In

each recovery unit, either (a) the average

annual ice-free period is expected not to

exceed 4 months over the next 100 years based

on model projections using the best available

climate science, or (b) the average annual

ice-free period is expected to stabilize at longer

than 4 months over the next 100 years based

on model predictions using the best available

climate science, and there is evidence that

polar bears in that recovery unit can meet ESA

Demographic Criteria 1, 2, and 3 under that

longer ice-free period.

In making this assessment, the focus is on the area

of seasonal or permanent sea ice supporting prey

resources that underlie the carrying capacity of

a recovery unit. An ice-free month is deﬁned as a

month during which less than 50% of the relevant

area of sea is covered by sea ice with more than

Polar Bear Conservation Management Plan 29

III. Management Goals and Criteria

50% ice concentration (based on monthly average

sea-ice concentration, or for more than 15 days if

based on daily sea-ice data). In addition to aligning

with the timeframe of the fundamental recovery

criteria, a 100-year period is used to allow long-term

feedbacks in the climate system to stabilize and to

average over short-term (decadal-scale) oscillations

associated with natural climate variability (Kay et al.

2011, Lovejoy 2014). The assessment of the stability

of the ice-free period in part (b) above should

accommodate the expectation that uncertainties in

100-year forcing scenarios and differences among

model ensembles may produce some forecasts with

subtle increases in the length of the ice-free period

(i.e., of no more than 1 month over 100 years), which

we accept as indistinguishable from “stable.”

These criteria may change in future revisions of

the Plan as more is learned about polar bears, their

habitat requirements, the availability of alternate

prey, and how polar bears and their prey populations

respond to diminishing sea ice. The sea-ice criteria

use model projections of sea ice extent as a proxy

for the amount of time polar bears will be forced

ashore or away from sea ice over shelf waters during

summer in the future. How an ice-free month is

deﬁned underpins the proxy’s efﬁcacy, and the

deﬁnition should be revised as more is learned about

what sea-ice conditions best predict when polar

bears arrive and depart from land, and how those

relationships differ in different recovery units.

Assessments of future sea-ice conditions should

be made using projections from an ensemble of

state-of-the-art, fully coupled, general circulation

models (GCMs) (Harris et al. 2014). Each model

in the ensemble should possess reasonable ability

to simulate past observations of seasonal sea-ice

dynamics (Wang and Overland 2009, Massonnet et

al. 2012). For projecting future sea-ice conditions,

the GCMs should be forced with one or more

scenarios that depict plausible levels of forcing for a

baseline future in which no presumptions are made

about greenhouse gas mitigation practices that have

not yet been adopted into law or that do not already

show empirical evidence of adoption. What consti-

tutes the baseline will hopefully change over time as

nations enact changes to stabilize global warming,

and future assessments should reﬂect these changes.

If more than one baseline forcing scenario is deemed

plausible, the sea-ice criteria should be evaluated

using projections from an unbiased representation

of the competing scenarios. Each model should be

represented by an equivalent number of realizations

(model runs), preferably more than one.

Using projections of future sea ice from climate

models assumes that the primary limiting feature

of the environment for polar bears is the sea-ice

platform itself, and that if the platform is stabilized

then polar bears will have adequate access to prey

(primarily ice seals). It is conceivable that changes

to the environment could alter the seal populations

and distributions so that even if the ice platform

were stabilized, polar bears would not have access

to suitable prey. Future status assessments should

consider prey abundance and prey availability and

reevaluate the assumption that sea ice is the sole

limiting factor for polar bear access to prey.

Although polar bears in several of the recovery

units have historically spent the majority of their

life on the sea ice, land has been and is increasingly

becoming important for denning and as a summer

refuge (Kochnev 2002, Ovsyanikov 2012, Fischbach

et al. 2007, Rode et al. 2015, Atwood et al. 2016).

Given that the extent of summer sea ice is projected

to decline through the 21st century (Overland and

Wang 2013, Barnhart et al. 2016), terrestrial habitat

is likely to become an increasingly important refuge

for polar bears. The ability of bears to maintain

access to terrestrial denning areas without compro-

mising foraging opportunities pre- and post-denning

may be an important factor determining whether

reproduction and cub survival is affected by sea-ice

loss (Derocher et al. 2004). This distributional

change may also have ramiﬁcations for the status

of the polar bear recovery units if use of terrestrial

habitat has ﬁtness or genetic implications.

While ice habitat is critical to the ability of polar

bears to access their prey, protection of denning and

summering habitats is and may become increasingly

important in supporting the long-term persistence

of polar bears, including in the Polar Basin Diver-

gent Ecoregion. Increased use of land is likely to

heighten the risk of human-bear interactions and

conﬂicts, particularly if anthropogenic activity in

the Arctic increases as projected (e.g., Vongraven et

al. 2012), the human population in the Arctic grows,

and management of attractants to polar bears is not

improved. Moreover, an expanding anthropogenic

footprint has the potential to inﬂuence the spatial

distribution, connectivity, and quality of lands that

might serve as terrestrial refugia for polar bears.

Currently, access to usable terrestrial habitats is

probably not compromised for polar bears, but

there is insufﬁcient data at this time to formalize

the criteria required to protect terrestrial habitat.

Further monitoring is needed of any potential

threats to polar bear terrestrial habitat use and

availability, and the effects those threats may have

on population vital rates.

The 2008 rule listing the polar bear as a threatened

species under the ESA acknowledged that there

were no known regulatory mechanisms in place at

the national or international level that directly and

effectively addressed the primary threat to polar

bears–-the rangewide loss of sea-ice habitat (73

FR 28288). Although Parties to the UNFCCC met

regularly to negotiate efforts to curb global green-

30 Polar Bear Conservation Management Plan

III. Management Goals and Criteria

house gas emissions and temper the threats posed

by continued global warming, their efforts lacked

broad international consensus and commitment.

Meanwhile, global CO

emissions have increased

60% over the past 25 years (Jackson et al. 2016),

leading some to conclude that a warming climate of

2 degrees C or more above the pre-industrial level

is unavoidable (Sanford et al. 2014). The agreement

by those Parties to the goal of “holding the increase

in the global average temperature to well below 2°C

above pre-industrial levels and to pursue efforts to

limit the temperature increase to 1.5°C” (Article

2.1(a), United Nations 2015) represents an impor-

tant step towards establishing a credible regulatory

mechanism designed to address the primary threat

to polar bears.

To keep net global warming well below 2°C, global

greenhouse emissions must be promptly and aggres-

sively reduced. Under a scenario of aggressive

GHG mitigation, Amstrup et al. (2010) forecasted

that polar bears in most regions of the Arctic could

have healthy populations if accompanied by full

implementation of well-designed wildlife manage-

ment. Atwood et al. (2016) forecasted a dominant

likelihood of greatly reduced polar bear populations

in two recovery units (the Polar Basin Divergent and

Seasonal Ice Ecoregions) based on contemporary

climate models forced with an aggressively miti-

gated emissions scenario (RCP 2.6). Nevertheless,

end-of-century model projections of sea ice under

the RCP 2.6 scenario show a likelihood that polar

bear populations could summer onshore for 4 or

fewer months in parts of all recovery units (Fig.

3), thus achieving Threats-based Criterion 1 (sea

ice), albeit with the possibility of greatly reduced

population sizes in some areas. And, since most

climate models do not project that the Arctic Ocean

will become entirely ice-free under the RCP 2.6

emissions scenario (Hezel et al. 2014), some polar

bears might adopt an alternative strategy (if viable)

of remaining on the sea ice as it retreats during

summer, then exercising an option to migrate

anywhere with abundant prey and sea ice during

winter.

Human-caused removals. There are multiple types

of direct, lethal removals of polar bears, including

legal harvest that meets management or conserva-

tion goals, legal harvest that results in overutiliza-

tion or other negative outcomes for management or

conservation, illegal harvest (poaching), authorized

incidental take, human-bear conﬂicts that result in

the death of polar bears, and polar bears killed as a

direct result of other human activity. In many of the

polar bear subpopulations where data are available,

mortality due to harvest exceeds mortality to

manage human-bear conﬂict, which exceeds human-

caused mortality from other sources (Shadbolt et al.

2012).

The subsistence harvest of polar bears, as repre-

sented by Fundamental Goal 4, was not identiﬁed as

a threat to polar bears in the listing rule, and should

not become a threat to recovery so long as harvest

occurs at a rate that has only a small or negligible

effect on the persistence of populations (Atwood

et al. 2016, Regehr et al. 2015). Guidelines for such

a rate for total human-caused removals, including

subsistence harvest, are established under the

MMPA-based demographic criteria associated with

Fundamental Goal 3 and related to Fundamental

Goal 4. In brief, these criteria seek to: (1) identify a

human-caused removal rate that maintains popula-

tions above the mnpl; (2) protect the opportunities

for subsistence harvest by minimizing other lethal

take; and (3) establish co-management of polar bears

by Alaska Native and Federal partners.

The ESA-based criterion for the total level of direct,

lethal removals for polar bears by humans, as

described here, does not replace the MMPA-based

criteria for human-caused removals. Rather, the

ESA-based criterion represents a less protective

take threshold at which removals would compromise

polar bear persistence in relation to Fundamental

Goals 1 and 2 (the MMPA-based criterion addition-

ally requires that take be low enough to allow the

population to stabilize above mnpl). A quantitative

Population Viability Analysis, similar to that used

for estimating demographic criteria, represents

an appropriate tool for evaluating the effects of

total human-caused removals following the tiered

framework proposed below.

The 2008 listing rule found that currently, human-

caused removals “[do] not threaten the polar bear

throughout all or a signiﬁcant portion of its range”

but that “Continued efforts are necessary to ensure

that harvest or other forms of removal do not exceed

sustainable levels” (73 FR 28280). Provided the

following criterion is met, human-caused removals

will not be considered a “threat” to recovery.

ESA Threats-based Criterion 2 (human-caused

removals): For each recovery unit, the total

level of direct, lethal removals of polar bears

by humans, in conjunction with other factors,

does not reduce the probability of persistence

below 90% over 100 years.

As written, this criterion is largely a recapitulation

of ESA Fundamental Criterion 2 (90% probability

of persistence in each recovery unit), with a focus

on the effect of human-caused removals on the

probability of persistence. In the event that an

appropriate quantitative model is not available to

assess this criterion, it could be evaluated using a

tiered approach:

Polar Bear Conservation Management Plan 31

III. Management Goals and Criteria

1. Criterion met: Total human-caused removals

are below the removal rate that maintains the

population above mnpl (h), as deﬁned under ESA

Demographic Criterion 4. Removals at this rate

are likely to have no effect, or a negligible effect,

on persistence. In this case, a population viabil-

ity analysis would not be needed to know this

criterion was met. As noted earlier, this is also

the most likely path to recovery, given the other

motivations in this plan to maintain removals at

or below this level.

2. Criterion possibly met: Total human-caused

removals exceed h but are below the upper

limit described under “Criterion not met.”

Removals within this range could result in

different outcomes, including: removals resulting

in equilibrium population size below mnpl but

with a negligible effect on persistence; removals

leading to a small equilibrium population size,

and therefore either having some negative effect

on persistence over the period of interest or

shortening the median time to extirpation; or

removals that have a high probability of resulting

in population sizes far below mnpl and a signiﬁ-

cant negative effect on persistence. The annual

removal rate and its effects must be balanced

against other Fundamental Goals and threats to

achieve the desired overall level of persistence

as stated in ESA Fundamental Recovery Crite-

rion 2. This is the range in which ESA Demo-

graphic Criterion 4 is not met but recovery is still

possible, provided the other demographic rates

exceed their minimal standards enough to meet

the persistence criterion. If the human-caused

removals in a recovery unit were in this range, a

population viability analysis would be needed to

assess this potential threat.

3. Criterion not met: Total human-caused removals

result in a 10% or greater decrease in the prob-

ability of persistence over 100 years, compared

to a scenario with no removals. At this upper

limit, removals would violate ESA Fundamental

Criterion 2 even in the absence of all other

threats.

Additional factors of potential future concern. A

number of other factors, including disease, ship-

ping, oil and gas development, and oil spills, were

evaluated in the 2008 listing rule for polar bears but

not found to be threats; thus, they do not require

threats-based recovery criteria. Further, because the

potential for these factors to become threats in the

future is distant or low enough (Atwood et al. 2016),

they do not warrant development of speciﬁc criteria

to indicate when they might become a threat.

At present, exposure to disease and parasites

is not a threat to the persistence of polar bears.

However, data on the exposure of polar bears to

disease agents and parasites are quite limited (i.e.,

restricted almost entirely to the Southern Beaufort

Sea subpopulation), and there is no information on

putative links between disease status and population

vital rates. The lack of information is a concern

given that climate change is expected to have both

direct and indirect effects on disease dynamics in

the Arctic due to changes in host-pathogen associa-

tions, altered transmission dynamics, and host and

pathogen resistance (Burek et al. 2008). Concern is

exacerbated by the fact that polar bears have a naïve

immune system (Weber et al. 2013), which may make

them particularly vulnerable to new pathogens, and

greater time on land during ice-free summers may

increase exposure to new pathogens. Thus although

the best available science currently indicates that

disease and parasites are not a threat to polar bears

(Atwood et al. 2016), periodic monitoring of polar

bear health (to include exposure to disease agents,

pollutants, and contaminants) is warranted.

With regard to the other factors, the continued

decline of summer sea ice will allow greater human

access to the Arctic Ocean, increasing the prospect

of oil and gas exploration and development (Gautier

et al. 2009) and the opening of new shipping routes

(Smith and Stephenson 2013). There are a number

of hypothesized ways this increased activity could

affect polar bears, but perhaps the greatest risk is

through exposure to oil spills, because even minimal

ingestion of oil by polar bears can be lethal (St.

Aubin 1990). Other activities, like coastal patrol,

research, and commercial ﬁshing, could also increase

with the decline of summer sea ice. But, changing

ice conditions have only recently allowed increased

human activities in the Arctic Ocean and limited

information exists to predict how polar bear popula-

tions would respond to increased human activity

(Peacock et al. 2011, Vongraven et al. 2012). The

current partnerships in the United States between

industry and natural resource management agencies

have led to successful mitigation efforts that have

limited disturbance to denning bears and reduced

the number of bears killed in defense of life, and are

likely to continue to do so in the near future. While

monitoring of these potential avenues of stress

to polar bears is warranted, these factors do not

require threats-based criteria at this time. In future

updates to this Plan, however, these factors should

be reevaluated.

32 Polar Bear Conservation Management Plan

III. Management Goals and Criteria

USFWS

D. Other Measures of Achievement

Fundamental Goals 4, 5, and 6 are not derived

directly from statute, but instead are included

because they are expressions of other societal values

that could be affected by polar bear management.

Performance requirements do not need to be

prescribed for these goals (as they do for ESA

recovery criteria and MMPA conservation criteria).

It is important, however, to measure achievement

of these goals, particularly to provide an adaptive

feedback loop for improving future conservation

actions. The following three measurement scales

provide quantitative expressions of these Funda-

mental Goals.

Fundamental Goal 4, measurement scale: Cumula-

tive take (all human-caused removals) level over

the next 50 years for each subpopulation that

includes parts of Alaska. The cumulative take level

over the next 50 years represents the opportunity

for subsistence harvest by multiple generations

of Alaska Natives combined with other forms of

human-removal. We strive to ensure sustainable

continued harvest opportunities, although providing

the opportunity does not require that the take

actually occurs at the full level speciﬁed under

MMPA Demographic Criterion 2. Note that harvest

management under the guidelines of this Plan may

include ongoing harvest—even for populations

that are declining due to environmental effects—as

long as the harvest is responsibly managed (in

accordance with the MMPA Demographic Criterion

2) and does not in itself become a driver of declining

ability to secure long-term persistence.

Fundamental Goal 5, measurement scale: Number

of human/bear conﬂicts in Alaska that result in

injury or death to humans or bears. With decreas-

ing sea ice, we anticipate an increase in the number

of bears onshore and an increase in human activities

in the Arctic. This combination will likely result in

an increase in human-bear encounters. To ensure

that the measurement scale actually reﬂects the

effectiveness of conservation efforts in improving

human safety, monitoring of additional variables

associated with human-bear encounters will be

needed to provide context.

Fundamental Goal 6, measurement scale: Econom-

ic impacts of polar bear management actions,

where “economic impacts” means additional cost

(direct expense, indirect expense, lost or foregone

opportunity, additional time) associated with a

speciﬁc action. This goal acknowledges that while

our primary goal is polar bear conservation, we

recognize the need for compatible economic activity

in the United States Arctic. The measurement

scale provides a means to consider whether and

how potential conservation strategies and actions

may affect economic development, both locally and

globally. This allows a more explicit consideration

of the trade-offs between economic development

and conservation actions, to seek solutions in which

economic development does not undermine the

ability to achieve recovery and conservation of polar

bears, and in which conservation does not unneces-

sarily limit economic development.

Polar Bear Conservation Management Plan 33

III. Management Goals and Criteria

E. The Population Dynamics of Conservation, Recovery, and Harvest

If we are successful in achieving the criteria

described in this Plan, what will conservation and

recovery of polar bears look like? The conserva-

tion criteria under the MMPA and the recovery

criteria under the ESA are not stated in terms of

desired population sizes, because conservation and

recovery could be achieved at different population

levels. Instead, the criteria are stated in terms of

demographic processes (e.g., persistence, survival,

reproduction, carrying capacity, anthropogenic

mortality) that link back to the fundamental goals

for polar bears, several of which were framed in

terms of probability of persistence. The concepts

behind the demographic processes may be unfamil-

iar to some readers, so it is fair to ask, what would

conservation and recovery look like? Why do all of

these criteria add up to fulﬁllment of the obligations

under MMPA and ESA? And how is it that harvest

can be compatible with conservation and recovery?

A picture of conservation

As described above, the proposed MMPA criteria

seek two things: to maintain the health and stability

of the marine ecosystem, as reﬂected in the intrinsic

growth rate and carrying capacity for polar bears,

above a certain level; and to maintain each polar

bear subpopulation above its maximum net produc-

tivity level. The ﬁrst MMPA criterion indicates

that there is a limit to the loss of carrying capacity

that can occur before the stability of the marine

ecosystem is lost and polar bears would cease to be

a signiﬁcant functioning element of the ecosystem

(Fig. 6, scenario 1). The threshold described in this

Plan indicates that a substantial portion (70%) of

the historical carrying capacity must be maintained

(where “historical” carrying capacity refers to the

carrying capacity in the decades preceding enact-

ment of the MMPA). If a declining carrying capacity

USFWS

Key Terms

Carrying capacity. The size at which a

population would stabilize if there were no direct

anthropogenic removals. The carrying capacity

can change over time, if the underlying habitat

changes.

Stable ecosystem threshold. The threshold for

carrying capacity identiﬁed in MMPA Conserva-

tion Criterion 1 below which the stability of the

marine ecosystem is unacceptably altered.

Intrinsic growth rate. The population growth

rate in the absence of anthropogenic removals

and at low density. This is the potential growth

rate, not the observed growth rate, and is an

important measure of the resilience of a popula-

tion.

Maximum net productivity level. The popula-

tion size at which the net growth in the popula-

tion (births minus non-anthropogenic deaths) is

greatest. Under the interpretation used in this

Plan, mnpl changes in proportion to carrying

capacity.

Quasi-extinction ﬂoor. The threshold for

evaluating “extinction” under the ESA in this

Plan. Rather than use outright extinction as the

condition to be avoided, we are using a more

conservative deﬁnition that avoids the conditions

that might give rise to an unavoidable downward

spiral. If a population crosses below this

threshold, it has ceased to persist, for purposes

of assessment under the ESA.

34 Polar Bear Conservation Management Plan

III. Management Goals and Criteria

stabilizes and is expected to remain stabilized above

the threshold associated with a stable ecosystem,

then the ﬁrst criterion is met (Fig. 6, scenario 3).

This criterion does not require that the historical

carrying capacity (Fig. 6, scenario 3, black line) be

maintained, but rather that the decrease in carry-

ing capacity is limited and ultimately stabilized;

the historical carrying capacity is nevertheless

a valuable reference point for understanding

the extent of decrease in carrying capacity and

associated ecosystem stability. Note that the ﬁrst

criterion concerns the carrying capacity, not the

population size (which may be below the carrying

capacity because of human-caused removals); if the

population size drops below the threshold, but the

carrying capacity does not, the criterion is still met,

although some thoughtful consideration of the level

of take might be prompted. In the absence of global

Figure 6. Achieving the MMPA conservation criteria requires keeping carrying capacity above the stable ecosystem

threshold, and keeping the population between mnpl and carrying capacity. Scenario 1 (red) shows the trend over

time of a subpopulation with well-managed take, but in an ecosystem that loses nearly all capacity to support polar

bears; this is the expectation for polar bears in most subpopulations if the threat of climate change is not abated.

Scenario 2 (purple) shows the trend over time of a subpopulation with unsustainable levels of take, which cause the

population size to decline below mnpl and may decrease population viability. Scenario 3 (green) shows the trend

over time of a subpopulation with well-managed take and an ecosystem that stabilizes before it reaches the point at

which the health and stability are lost, even though a portion of the original carrying capacity is lost. The black line

in scenario 3 provides a reference to the carrying capacity in the absence of an anthropogenic effect on polar bear

habitat. This ﬁgure is a simpliﬁcation for the purpose of illustration; assessment of the criteria will also need to take

into account annual variation, precision of estimates, and other considerations.

1

Time

SubpopulationSize

1

Time

SubpopulationSize

1

Time

SubpopulationSize

CarryingCapacity(K)

MNPL

PopulationSize

StableEcosystemFloor

Scenario

Polar Bear Conservation Management Plan 35

III. Management Goals and Criteria

efforts to abate the causes and effects of climate

change, scenario 1 is the expectation for polar bears

in most subpopulations; substantial worldwide effort

would be needed to turn scenario 1 into scenario 3.

Achievement of this goal is the most important and

ambitious aim of this Plan.

The second MMPA criterion addresses the level of

human-caused removals of polar bears. The maxi-

mum net productivity level (mnpl) is the population

size at which the net productivity (birth and survival

of juveniles to adulthood, minus deaths of adults) is

greatest; for polar bears, this is estimated to occur

at about 70% of the carrying capacity (Regehr et al.

2015). We have interpreted the mnpl as proportional

to the carrying capacity at any point in time (Fig.

6)—as carrying capacity declines, so does the

population size at which productivity is highest.

If human-caused removals exceed the allowable

rate, the population will decrease below mnpl

(Fig. 6, scenario 2). If all human-caused removals,

including subsistence take, are well-managed, then

the population size should remain between mnpl

and carrying capacity (Fig. 6, scenarios 1 and 3).

To do this requires adjusting the total take as the

population size declines, as the intrinsic growth rate

declines, or both.

Thus, scenario 3 (green) in Figure 6 shows a picture

of successful achievement of both MMPA conserva-

tion criteria developed in this Plan. This picture,

however, is not the current expectation for most of

the subpopulations worldwide. The second MMPA

criterion (maintenance of mnpl) is not a primary

concern, because the United States will continue

to work with its partners to maintain the Southern

Beaufort and Chukchi Sea populations above

mnpl, and because processes exist, or are being

initiated by the individual Range States, to manage

human-caused removals in many of the other

subpopulations. On the other hand, in all four of the

ecoregions, signiﬁcant loss of carrying capacity is

expected as the extent, thickness, and duration of

sea ice decline (Atwood et al. 2016). Although the

speciﬁc analyses have not been completed against

the ﬁrst MMPA criterion (ecosystem health and

stability), the best scientiﬁc information available

suggests that in at least three of four ecoregions,

this criterion is not expected to be met within 50–100

years (e.g., scenario 1 in Fig. 6). Thus, to achieve

the conservation purposes of the MMPA for polar

bears, global actions need to be taken to reduce the

long-term loss of sea ice to tolerable levels, while

responsibly managing all forms of human-caused

removal, including subsistence harvest.

A picture of recovery

The ESA criteria described above fundamentally

seek a high degree of assurance that viable popula-

tions of polar bears (as deﬁned for the purposes of

this Plan) will persist in all four ecoregions for a

long period of time. To achieve such assurance, three

important qualities of the populations are needed:

resilience, buffering, and limited removals. Resil-

ience arises when the intrinsic population growth

is high, so that the population can quickly rebound

from any short-term decline; such resilience comes

from having high survival and reproductive rates

(ESA Demographic Criteria 1 and 2). A high

carrying capacity buffers the population from the

risk that natural variation will cause it to decline

to unacceptable low levels (ESA Demographic

Criterion 3). Finally, human-caused removals (for

any purpose, including defense-of-life and subsis-

tence) remove some of the resilience (by reducing

the survival rate), so they must be limited (ESA

Demographic Criterion 4). To assure long-term

persistence, these criteria not only need to be met at

the time of assessment, but also at all points in time

going forward 100 years from that point.

Currently, polar bears do not meet these criteria in

at least three ecoregions (Seasonal Ice, Polar Basin

Divergent, and Polar Basin Convergent). Based on

forecasts of atmospheric gases, Arctic air and sea

temperatures, and sea-ice extent, polar bear popula-

tions are expected to decline to small fractions

of their historical population sizes (Atwood et al.

2016). The red line in Figure 7 shows a hypothetical

scenario that roughly matches the expectation for

one or two of the ecoregions (including the Polar

Basin Divergent ecoregion)—as sea ice is lost, the

population will decline precipitously, crossing below

the threshold at which the dynamics of small popula-

tions take over. These dynamics include demograph-

ic stochasticity, Allee effects, and inbreeding, which

may create an “extinction vortex” that leads to

nearly inescapable extinction. The population level

at which these small population dynamics take over

is called the quasi-extinction ﬂoor and represents

failure—the effective loss of bears in an ecoregion.

To achieve recovery, the forecast trend needs to

be changed, so that the population is expected to

remain safely buffered above the quasi-extinction

ﬂoor. In most species that have recovered under the

ESA (e.g., wolves, bald eagles, peregrine falcons),

the trajectory looked like the blue line in Figure 7:

the species showed a substantial decline; the species

was listed under the ESA, often as the population

approached a perilous point; recovery actions were

implemented and the population trend turned

around; then delisting occurred when the long-term

prognosis was secure. But note that recovery under

the ESA did not necessarily return these species

to historical levels, only to levels that assured the

species no longer needed the protection of the ESA.

Polar bears were listed at a much earlier stage

because the primary threat, loss of sea ice, could be

foreseen in advance. With this advanced notice, we

have the potential opportunity to achieve recovery

without ever approaching perilously low numbers

36 Polar Bear Conservation Management Plan

III. Management Goals and Criteria

(green line, Fig. 7). Although we would, of course,

prefer never to see a decline in polar bear numbers,

if we can turn the red line in Figure 7 (the current

status, with projected declines) into the green line,

we will have achieved a huge conservation success,

and polar bears would no longer need the protection

of the ESA.

The ESA criteria in this Plan add up to recovery.

Achievement of the demographic criteria would

indicate that the populations in each ecoregion were

resilient, and would remain so for a long period of

time. The carrying capacity criterion, coupled with

considerations of distribution and connectivity,

would ensure enough redundancy within each

ecoregion to buffer against the effects of environ-

mental variability and catastrophic events. The

achievement of these criteria in all four recovery

units would confer representation, ensuring that

the genetic, behavioral, life-history, and ecological

diversity of polar bears is conserved. Achievement

of the threats-based criteria would indicate that

the threats that led to listing had been addressed.

Finally, achievement of the fundamental criteria

indicates that the likelihood of becoming endangered

had been reduced to the point that polar bears no

longer needed the protections of the ESA. While it

may seem counterintuitive that all of this might be

achieved while still losing a substantial portion of the

present population, this is a consequence of having

been able to list polar bears early enough to address

a long-term threat. Reﬂection on past successful

recovery efforts shows that rather than a return to

historical levels, the ESA strives to reduce threats

to the point that the species is not in danger of

extinction, nor likely to become so in the foreseeable

future, throughout all or a signiﬁcant portion of its

range. For many species, recovery can be achieved

at less than historical population levels.

The compatibility of harvest with conservation and

recovery

It is not unusual to authorize incidental take of a

species protected under either the MMPA or the

ESA, and the standards for such authorization are

well described and well implemented. It is, however,

much less common to purposefully seek to harvest

species that need the protections of the ESA or

the MMPA, but it does occur in a small number of

special cases. Subsistence harvest of polar bears

for a variety of cultural and nutritional purposes

Figure 7. Achieving ESA recovery criteria requires keeping the population level high enough that there is a low

chance of ever crossing below the quasi-extinction ﬂoor. Three hypothetical scenarios show population response to a

substantial loss of habitat. Recovery occurs when the threats are adequately ameliorated and available information

indicates with a high degree of conﬁdence that the population will not drop below the quasi-extinction ﬂoor. This

requires resilience in the population (high potential growth rate) as well as a buffer (carrying capacity far enough

above the ﬂoor), but does not require the population to return to historical levels. The green and blue lines depict

hypothetical species trajectories where adequate management of threats occurs, stopping the decline and resulting in

stability, either without (green) or with (blue) the need for some restoration, whereas the red line depicts a situation

where threats are not ameliorated and the species’ status deteriorates until extinction occurs.



1

0 20 40 60 80 100 120

Time(yr)

PopulationSize

Listed (threatened)andnotrecovered

Quasi‐extinction floor

Recovered(threats avertedearlier)

Recovered(threatsaverted later)

Minimumcarryingcapacity

Polar Bear Conservation Management Plan 37

III. Management Goals and Criteria

is a central tradition for Alaska Native people, as

well as other native Arctic peoples. The ESA and

MMPA both recognize the importance of subsistence

harvest for Alaska Native people. In fact, both

laws allow certain subsistence harvest by Alaska

Native people even when a species is “threatened”

or “depleted.” In this Plan, we recognize continued

subsistence harvest as a fundamental goal associ-

ated with polar bear conservation and recovery. We

also provide conditions for harvest to ensure: under

the ESA, that harvest does not appreciably reduce

the likelihood of survival or recovery; and under the

MMPA, that harvest does not affect our ability to

achieve the conservation goals of the Act.

The guidelines for harvest management described

in Section IV.b of this Plan outline a three-level

framework for implementation at the subpopulation

level (Fig. 8). The central idea of this framework is

that harvest opportunity can be maintained if its

management is sensitive to any changes in popula-

tion size, intrinsic growth rate, or carrying capacity.

The three zones arise out of an effort to balance the

Fundamental Goals of this Plan. In the green zone,

the opportunity for subsistence harvest (Funda-

mental Goal 4) dominates the management of take,

because the conservation goals (Fundamental Goals

1–3) are not facing near-term risk. In the red zone,

the conservation goals (Fundamental Goals 1–3)

dominate the management of take because threats

to the species have become severe, and thus, harvest

opportunity needs to be curtailed. In the yellow

zone, we seek a balance of the two sets of goals, with

continuation of some degree of harvest opportunity

while watching the conservation status carefully.

The concepts underlying this framework for

management of human-caused removals are founded

in harvest theory (Wade 1998, Runge et al. 2009)

and a careful consideration of polar bear population

dynamics. Appendix C provides the scientiﬁc basis

for managing harvest opportunity in a manner

compatible with the conservation and recovery of a

species that is expected to decline in the near- and

mid-term.

Figure 8. Three-level framework for management of polar bear take. In the green zone, the maximum number of

annual removals is proportional to the population size, with the proportion (the rate) sensitive to any changes in the

intrinsic rate of growth of the population. In the yellow zone, additional efforts are warranted, including consideration

of increased monitoring effort, reduction of defense-of-life or other removals, and reduction in subsistence harvest. In

the red zone, emergency measures to reduce or minimize all human-caused removals are recommended. In all three

zones, the colored region represents the range of removal rates that meet the conservation guidelines of this Plan;

the local choice of where to fall within those bounds can take into account the speciﬁc context of the subpopulation.



1

Discretionaryhuman‐caused

removalrate

(proportionofpopulationsize)

PopulationStatus

(takingintoaccountN,K,r,andqualityofinformation)

Removalsarenot

athreattothe

sub‐population

Removals

areathreat

Workhardtomake

sureremovalsdonot

becomeathreat

Removals are not a threat

to the sub-population

Removals

are a threat

Work hard to make sure

removals do not become

a threat

38 Polar Bear Conservation Management Plan

III. Management Goals and Criteria

F. Uncertainty, Assumptions, and the Need for Adaptive Feedback and

Management

The links between the tiers of criteria in this

framework are based on our current understanding

of polar bear demography and threats, which is

incomplete. Thus, in deriving demographic criteria,

assumptions and uncertainty about the demographic

processes (such as regarding Allee effects), the

means and variances of the survival and reproduc-

tive rates, the mechanism and magnitude of density-

dependence, and the role of density-independent

drivers of change give rise to uncertainty about the

demographic criteria. Likewise, the derivation of

threats-based criteria is affected by various types

of uncertainty, such as: uncertainty regarding the

nature, mechanism, and magnitude of the various

threats; uncertainty about the behavioral responses

of polar bears to changing conditions in the marine

ecosystem, such as prey base, denning conditions,

and other effects of climate change; uncertainty in

the trajectory of sea ice as driven by climate change;

and uncertainty in climate forecasts themselves. We

recognize there are other gaps in knowledge that

add to scientiﬁc uncertainty. Even if there is strong

policy certainty about the fundamental criteria, the

demographic and threats-based criteria might be

less certain, because of the scientiﬁc uncertainty

inherent in their derivation. We also acknowledge

policy uncertainty in the establishment of the

fundamental criteria themselves.

The standards established in this Plan, however,

meet the statutory requirements of the MMPA and

ESA and will result in conservation and recovery,

even in the face of the uncertainties described

above. To achieve the statutory requirements in the

face of uncertainty, we needed to err on the side of

conservation and recovery of polar bears, possibly

at the cost of other fundamental goals. If and when

uncertainties are resolved, it is more likely than

not that the conservation and recovery criteria

can become less demanding, allowing even better

achievement of the other goals.

For these reasons, this Plan should be viewed as

dynamic, not static, and the criteria should be

revised over time as new data are acquired and

critical scientiﬁc and policy uncertainties are

reduced or resolved. The fundamental criteria could

be revised if policy insights arise. Depending on

the nature of any changes that may be made in the

fundamental criteria, the demographic criteria may

change. Further, even if the fundamental criteria

do not change, the demographic criteria may be

ﬁne-tuned as new scientiﬁc information increases

our understanding of polar bear population dynam-

ics. The threats-based criteria will likely be subject

to revision as new data help us understand the

nature of the current and emerging threats and

the responses of polar bear populations to them.

Any changes to the demographic and threats-based

criteria will remain founded in the fundamental

criteria.

It is the intent of this Plan to use an adaptive

management approach to revise and update the

fundamental goals, conservation criteria, and

recovery criteria, as well as various assumptions

underlying our analyses, as new scientiﬁc and policy

information becomes available that demonstrates

such revisions are appropriate. By using such an

adaptive feedback approach, we will be able to

identify triggers for such revisions to conservation

and recovery criteria and, therefore, maintain

transparency and support for any modiﬁcations.

USFWS

Polar Bear Conservation Management Plan 39

IV. Conservation Management Strategy

IV. CONSERVATION MANAGEMENT STRATEGY

A. Collaborative Implementation

Implementation of the Conservation Management

Plan will rely on the participation of Alaska Native,

Local, State, Federal, Range States, and private

partners with a vested interest in polar bears in the

Alaskan Arctic. This strategy primarily focuses on

the actions within the purview of the partners who

developed this Plan; however, in the long term the

recovery and conservation of polar bears will depend

on actions taken by a much larger group of nations,

agencies, companies, entities, and individuals to

address the primary threat, as well as potential

future threats. With the exception of management

of atmospheric greenhouse gases, which requires

global engagement, this Plan addresses the actions

that can be taken under the jurisdiction of partners

in the Alaskan Arctic with an interest in polar bears.

Thus, in the text to follow, “we” refers to those

agencies and entities who will be primarily involved

in its implementation. This Plan focuses mostly on

actions needed to conserve and recover the polar

bear subpopulations linked to the United States. It

was generally not practicable to develop conserva-

tion and recovery actions for the subpopulations

outside of the United States. Given the autonomy

and unique statutory and cultural considerations of

individual Range States, developing actions beyond

what is included in this Plan would not promote the

conservation and survival of the species. However,

this Plan will be part of the Circumpolar Action Plan

for polar bears that was developed by the ﬁve Range

States with the goal of achieving polar bear conser-

vation rangewide. In addition, there are actions

outside the context of this Plan that the United

States government may undertake bilaterally or

multilaterally to advance polar bear conservation

internationally.

A Recovery Implementation Team will be created

to coordinate implementation, monitoring, and

research activities to maximize efﬁciency and

effectiveness with available resources. The Imple-

mentation Team will evaluate progress toward the

criteria identiﬁed in Section III of this Plan and

will make recommendations regarding appropriate

adaptive management. It will serve as a venue

for the exchange of data, ideas, and information

among agencies, Native communities, entities, and

interested parties. In turn, it will make summaries

available to the public.

The Implementation Team will be composed of

representatives from Alaska Native, State, Federal,

International, and private agencies and entities

with a vested interest in and authority to manage

for polar bear conservation. The majority of the

focus of the Implementation Team will be on the

Polar Basin Divergent Ecoregion, speciﬁcally the

two United States subpopulations. Recognizing

that recovery of polar bears requires effort in

each ecoregion, however, the USFWS will remain

active in implementing the 1973 Agreement on

the Conservation of Polar Bears and the 2000

Agreement with the Government of the Russian

Federation on the Conservation and Management

of the Alaska-Chukotka Polar Bear Population.

Similarly, the USFWS will remain an advisor to

the Inuvialuit-Inupiat Polar Bear Management

Agreement for management of polar bears in the

Southern Beaufort Sea subpopulation and will

welcome opportunities to engage with Canada under

the 2008 Memorandum of Understanding for the

Conservation and Management of Shared Polar

Bear Populations.

The Implementation Team will consist of an Execu-

tive Committee that will provide overall guidance

on Plan implementation and be broadly responsible

for leading the Team by sharing and promoting the

exchange of data and information on: Alaska polar

bear populations and their habitat; threats; and

ongoing management, monitoring, and research

activities. The Executive Committee will produce

reports at least every two years highlighting

ongoing activities and tracking progress toward

the fundamental, demographic, and threats-based

criteria. The Executive Committee is not a decision-

making body, although it may provide recommenda-

tions to member agencies and entities on topics

such as priorities, funding, and cooperative projects.

The Executive Committee does not supersede the

authority of the USFWS or other member agencies.

The Executive Committee will establish Working

Groups as needed to address key issues and focus

areas (Fig. 9). Initially, Working Groups will be

created to address the following: (1) Science—

including both monitoring and research; (2) Human-

Polar Bear Interactions; and (3) Communications.

The goal is to have the Science Working Group

focused on the speciﬁc monitoring actions to track

the fundamental, demographic, and threats-based

criteria contained in this Plan. The Science Group

will also serve as a forum for exchange of informa-

tion on ongoing and planned research activities and

also to identify priority areas for research initia-

tives into the future. When considering research

opportunities, the Science Working Group will focus

on applied research, with a strong emphasis on

knowledge that will help to achieve the fundamental

goals in this Plan. Both the monitoring and research

aspects of the Science Work Group should appropri-

ately integrate empirical knowledge and Traditional

40 Polar Bear Conservation Management Plan

IV. Conservation Management Strategy

Ecological Knowledge (Voorhees et al. 2014) and

should support the use of new technologies and

less-invasive methods.

The Working Groups and the Executive Committee

are not entities charged with action. They are

focused on coordinating and making recommenda-

tions. It is ultimately up to the individual agencies,

entities, and organizations themselves to take

actions consistent with their mandates, priorities,

and available resources. For example, a Commu-

nication Working Group may identify a need for

information to be provided to local communities on

deterrence methods for polar bears. Once this need

was identiﬁed, the responsible agencies or entities

would inform the Executive Committee whether this

was an action they could implement.

The Communication Working Group will be asked

to work with the Executive Committee to establish

a website to facilitate information exchange within

the Executive Committee as well as with the general

public. In the ﬁrst ﬁve years of its existence, the

Polar Bear Conservation Management Plan

Implementation Team will meet at least twice a year.

The intention is that one meeting will be an annual

assessment focused on documenting activities

conducted and new information made available

over the prior calendar year and looking forward

to planned activities for the upcoming calendar

year. The information on actions and progress in

the United States can then be provided as input to

monitor the Circumpolar Action Plan. A check-in

meeting will be held at approximately the six month

point to assess whether activities have proceeded

as planned and to make adjustments, as necessary

and appropriate. The meetings may occur in person

or by teleconference, as needed. After the ﬁrst ﬁve

years, the Implementation Team should reconsider

the schedule on which it meets. Terms of reference,

appointment letters, and roles and responsibilities

for the Executive Committee and associated

Working Groups will be developed so that they can

be issued along with the ﬁnal Conservation Manage-

ment Plan. The structure and functions outlined

here may be adjusted as implementation proceeds;

changes will be made to accommodate unanticipated

challenges and needs.

Figure 9. Structure of the Polar Bear Recovery Implementation Team.

Polar Bear Recovery Implementation Team

Recovery Plan Advisor

USFWS Polar Bear Team

Executive Committee

Members: Federal, State, Tribal

Management Agencies

(Chair: USFWS, Alaska Regional Director

or Assistant Regional Director)

Human-Polar Bear

Conflicts Working Group

Communications Working Group

Science Working Group

Polar Bear Conservation Management Plan 41

IV. Conservation Management Strategy

B. Conservation and Recovery Actions

The following high-priority actions (each explained

in detail below) are necessary to achieve the funda-

mental goals of this Plan:

 Limit global atmospheric levels of

greenhouse gases to levels appropriate for

supporting polar bear recovery and conser-

vation, primarily by reducing greenhouse

gas emissions

 Support international conservation efforts

through the Range States relationships

 Manage human-bear conﬂicts

 Collaboratively manage subsistence harvest

 Protect denning habitat

 Minimize risks of contamination from spills

 Conduct strategic monitoring and research

Aside from actions to promote swift and substantial

reductions in greenhouse gas emissions at the global

and other large scales, the actions above are primar-

ily, but not exclusively, focused on the United States

portion of the Polar Basin Divergent Ecoregion

with a management focus on the two subpopulations

shared by the United States. Many of the actions

emphasize the importance of local engagement and

implementation and are already underway. The

role of this Plan and the Implementation Team is to

continue and expand those actions, using adaptive

management to make them more effective where

possible.

Time and cost. The cost estimates in this document

are the projected annual costs, including salaries, for

2017–2022 as required to meet the proposed conser-

vation needs for the United States portion of the

Polar Basin Divergent Ecoregion during this initial

ﬁve-year period. We anticipate that continuation

of all of the high priority recovery actions will be

necessary until sea-ice loss is no longer driving the

population towards extinction or until our adaptive

management efforts lead us to identify new priori-

ties. Therefore, estimated costs to full recovery are

shown by projecting forward in ﬁve-year increments

each of the costs included, with appropriate adjust-

ments for inﬂation, until either of those conditions

occurs. These cost estimates are signiﬁcantly higher

than current funding for polar bear management

and research in the United States as some needs

are currently not adequately addressed. All cost

estimates are approximate and subject to revision.

The actions described here will be undertaken if and

when funding is available.

Contingent on funding, these actions, if not already

underway, will be initiated in the next ﬁve years and

should continue until the effects of climate change

no longer pose a threat to polar bear conservation,

and recovery criteria have been met.

Management Actions that were considered but

not identiﬁed as high priority recovery actions are

included in Appendix B.

Limit global atmospheric levels of greenhouse

gases to levels appropriate for supporting polar

bear recovery and conservation, primarily by

reducing greenhouse gas emissions

As previously stressed, the single most important

action for conservation and recovery of polar bears

is a prompt and aggressive global reduction in the

emission of greenhouse gases contributing to Arctic

warming (Amstrup et al. 2010). More action is

needed in the United States and elsewhere to move

from the current baseline trajectory to an aggres-

sive effort to curtail emissions globally. Recently,

steps have been taken towards achieving this goal.

In December 2015, world leaders secured a global

agreement to combat climate change, but additional

commitments are still needed to keep global warm-

ing below 2 degrees C. In the U.S., domestic efforts

are underway to inspire that change by informing

key audiences about the likely impacts of changes

in global climate (see for example, U.S. Department

of State, 2015, initial GHG reduction pledge http://

www4.unfccc.int/submissions/INDC/Published%20

Documents/United%20States%20of%20

America/1/U.S.%20Cover%20Note%20INDC%20

and%20Accompanying%20Information.pdf; U.S.

Global Climate Change Research Project http://

www.globalchange.gov; and Environmental Protec-

tion Agency http://www.epa.gov/climatechange).

One speciﬁc contribution to this effort will be

research to better understand linkages between

atmospheric concentrations of GHG, sea ice, and

polar bear resource selection and demographics. A

second contribution will be to develop and deliver

a communication strategy that articulates the

consequences to polar bears and their habitat of the

likely effects of the current baseline GHG emissions

scenario compared to one that reﬂects an aggres-

sive approach to curtailing emissions worldwide.

The strategy will also communicate the effects of

climate change on coastal Arctic peoples who derive

cultural and nutritional beneﬁt from polar bears.

The ultimate goal of our communication effort is

to prompt the needed actions to maintain and, as

needed, restore, sea-ice habitat by implementing

sufﬁcient regulatory, market-driven, and voluntary

actions at global and national scales to address the

anthropogenic causes of Arctic warming and abate

the threat to polar bears posed by sea-ice loss.

42 Polar Bear Conservation Management Plan

IV. Conservation Management Strategy

Support international conservation efforts through

the Range States relationships

Work closely with other Range States to implement

conservation actions outlined in Circumpolar

Action Plan for the global population. Polar bear

range reaches ﬁve Arctic nations. These Range

States have long recognized the need to coordinate

polar bear conservation efforts (1973 Agreement

on the Conservation of Polar Bears). In their

capacity as parties to that Agreement, the Range

States adopted a Circumpolar Action Plan in

2015. The purpose of the Circumpolar Plan is to

broadly address range-wide conservation challenges

such as the threat to polar bears posed by global

greenhouse gas emissions, and potential threats like

human-bear conﬂicts and illegal trade, which must

be effectively managed for the species to survive

until climate change is addressed. As a Range State,

we anticipate contributing to the implementation of

international priorities that coincide with our own

priorities and are in alignment with our statutory

responsibilities. We also plan to share strategies

and best management practices with our Range

State partners. In turn, advances in knowledge and

management practice made by Range State part-

ners will actively inform implementation of this Plan

in the United States. The Recovery Team recognizes

that there may be beneﬁt in supplementing this Plan

and the Circumpolar Action Plan with additional

national or international actions for the beneﬁt of

Arctic ecosystems and polar bears.

Pursue targeted conservation efforts with Canada

and Russia by sharing resources and expertise.

Along with implementation of measures in the

Circumpolar Action Plan focused on polar bear

conservation range-wide, we anticipate undertak-

ing speciﬁc conservation efforts with Russia and

Canada, international neighbors with whom we

share management of the Chukchi Sea and Southern

Beaufort Sea polar bear subpopulations, respec-

tively. Speciﬁcally, we will work with Russia to better

monitor and manage human-caused removals in that

country. Based on recent information, polar bear

take in Russia may be declining (Kochnev 2014) but

in past accounts, mortality was thought to be large

(Aars et al. 2006). We will also work with Russia to

protect denning habitat in Chukotka and on Wrangel

Island, where almost all denning for the Chukchi

Sea population occurs (Garner et al. 1990). Likewise,

in addition to working with Canada on issues related

to the Southern Beaufort Sea subpopulation, we

will provide support to Canada’s efforts to manage

polar bears in the Canadian Archipelago, which we

anticipate will provide key terrestrial polar bear

refugia as sea ice declines (Derocher et al. 2004;

Amstrup et al. 2008, 2010; Peacock et al. 2015).

Conservation and recovery actions

Appropriate entities, both in the U.S. and internationally, will implement regulatory, market-driven, and

voluntary actions to address the anthropogenic causes of Arctic warming and abate the threat to polar

bears posed by sea-ice loss by keeping global warming below 2 degrees C. (Cost undeterminable)

(i). USFWS and partners will develop and deliver an effective communications strategy to inform

United States and global audiences of the urgent need to reduce greenhouse gas emissions and

the beneﬁts to polar bears and to coastal Arctic peoples of doing so. ($685,000)

(ii). USFWS and partners will continue their efforts to reduce their own GHG emissions consis-

tent with Executive Orders and other organizational directives. ($7,000,000)

Total cost: minimum of approximately $7,685,000 per year

Conservation and recovery actions

1. Work closely with the other Range States to implement the conservation actions outlined in the Circum-

polar Action Plan for polar bears range-wide that are consistent with national priorities and in alignment

with statutory responsibilities.

2. Work with Russia to (a) protect denning habitat in Chukotka and Wrangel Island through development

of den detection models and avoidance strategies; and (b) better monitor human-caused removal of polar

bears in Russia and jointly improve efforts to minimize human-bear conﬂicts.

3. Provide support for polar bear management efforts in the Canadian Archipelago.

Total cost: approximately $729,000 per year

Polar Bear Conservation Management Plan 43

IV. Conservation Management Strategy

Manage human-polar bear conﬂicts

With reduced ice extent, increasing numbers

of polar bears with poorer body condition than

observed historically are making their way to shore

earlier in the spring and staying later in the fall

(Obbard et al. 2006). Once on land, polar bears are

unable to reach their preferred food, ice seals, so

they primarily fast (Ramsay and Hobson 1991)

or scavenge (Miller et al. 2004). Simultaneously,

reductions in summer sea ice will allow expanded

development opportunities and growing human

activity in polar bear habitat (Vongraven et al. 2012).

These factors increase the likelihood of human-bear

conﬂicts with negative consequences for both

humans and bears.

Minimizing lethal take of polar bears from human-

bear conﬂicts, including take from industrial,

research, or other activities, contributes to polar

bear conservation over the long term (Fundamental

Goal 3) and in the near term, protects opportunities

for continued subsistence harvest (Fundamental

Goal 4). From a demographic perspective, wildlife

populations are affected by the total level of direct

human-caused removals. For polar bears, there are

several types of removals that have different causes

and different value to humans. Consistent with

provisions in the ESA and MMPA, this Plan recog-

nizes the importance of providing opportunities

for subsistence harvest as an inherently important

component. Lethal take of polar bears incidental

to human-bear conﬂicts, industrial operations, or

research activities should be minimized because

they have negative implications for the conservation

of subpopulations in the United States including

potentially reducing opportunities for subsistence

harvest.

Provisions to minimize these other sources of

take will continue to be implemented within the

existing regulatory frameworks (e.g., the USFWS

Incidental Take Program under the MMPA, for

industrial activities) or review processes (e.g., the

USGS, USFWS, and ADF&G Institutional Animal

Care and Use Committees, for research activities).

Examples of these ongoing efforts include partner-

ships with the oil and gas industry over the past 30

years of operations on the North Slope, and polar

bear patrols led by the North Slope Borough. To

build on these efforts, we will develop an overarch-

ing strategy and best management practices to

prevent, monitor, and manage human-polar bear

conﬂicts in the United States. Those practices will

include rapid response plans for situations where

a large number of hungry bears are stranded on

shore.

We will work with local communities and with

industry to develop human-polar bear interaction

and safety plans that include attractant manage-

ment (to minimize bears being attracted to human

communities for food), bear awareness training,

safety procedures for bear encounters, proper bear

hazing techniques, and reporting requirements. And

we will work with communities to implement the

components of those plans such as best practices for

garbage management at households and community

landﬁlls, bear-proof food-storage options, and loca-

tion of whale bone piles to reduce food attractants

that draw polar bears into human communities.

We will continue to support local capacity for polar

bear patrols and other management efforts directed

towards residents and visitors. Speciﬁcally, we will

expand the scope and improve the effectiveness of

USFWS

44 Polar Bear Conservation Management Plan

IV. Conservation Management Strategy

community polar bear patrols through consistent

funding, standardized methods, and better reporting

of data on interactions through our work with the

Range States Conﬂict Working Group and the Polar

Bear Human Interactions Management System

(PBHIMS database).

Conservation and recovery actions

1. Develop and communicate a strategy to prevent, monitor, and manage human-polar bear conﬂicts for

the subpopulations in the United States with input from local residents, conservation partners, and invited

experts.

2. Develop and communicate response plans for the subpopulations in the United States to address the

prospect of increasing numbers of hungry bears on shore with input from local residents, conservation

partners, and invited experts.

3. Develop and implement human-polar bear interaction and safety plans for United States communities

with polar bears, to include attractant management, bear awareness training, safety procedures for bear

encounters, proper hazing techniques, and reporting requirements.

4. Reduce attractants in United States communities with polar bears, through development and distribu-

tion of best practices for garbage management and food storage.

5. Improve the scope and effectiveness of United States community polar bear patrols, through increased

funding, standardized methods, and better reporting of data on interactions.

Total cost: approximately $1,282,000 per year.

Collaboratively manage subsistence harvest

The co-management of polar bears by Alaska Native

and Federal partners is supported under domestic

laws and the 1973 Agreement on the Conservation

of Polar Bears, recognizing the importance of

co-management for maintaining the ability of Alaska

Native people to meet nutritional and cultural needs,

mitigating human-polar bear conﬂicts, monitoring

subsistence harvest, and ensuring subsistence

harvest rates that are consistent with the manage-

ment and conservation goals described in Section

III of this Plan.

In this Plan, we adopt a framework for identifying

limits on total human-caused removals. The goals

of this framework include: to ensure that remov-

als do not have a negative effect on population

persistence, thus increasing the likelihood that

recovery is possible once climate change has been

addressed; and to provide long-term opportunities

for subsistence use of polar bears by Alaska Natives.

A co-management system between Alaska Native,

Federal, and other partners provides the foundation

for this framework and its success. This includes

the ability to monitor take and collect biological

samples from harvested polar bears (e.g., through

the USFWS Marking, Tagging, and Reporting

Program and the North Slope Borough) and the

ability to adjust harvest rates towards adherence

with the principles in Section III of this Plan (e.g.,

through the U.S.-Russia Bilateral Agreement and

the Inupiat-Inuvialuit Agreement). Because both

United States polar bear subpopulations are shared

with other countries, continued cooperation with

international partners is necessary for responsible

management and conservation.

The framework for management of human-caused

removals, including subsistence harvest, is founded

on three principles. First, human-caused removals

are managed at the subpopulation level by the

appropriate co-management partners, taking into

account factors speciﬁc to that subpopulation (e.g.,

traditional practices, management objectives, and

local conditions). Second, annual removal levels

are state-dependent with respect to population size

(and by extension, carrying capacity) and intrinsic

growth rate. Thus, the framework is intended to

account for multiple ecological mechanisms through

which ecological change (e.g., loss or gain of sea-ice

habitat, decrease or increase in prey availability)

and other factors could affect polar bears. Third,

a three-level system identiﬁes thresholds at which

increasing efforts are taken to minimize the effects

of human-caused removals (Fig. 8).

Under the three-level system, graduated manage-

ment and conservation actions are tied to pre-

established thresholds. Above the upper threshold,

the subpopulation shows a resilient intrinsic rate of

growth and the carrying capacity provides a large

buffer against the risk of extirpation (Fig. 8, green

zone). In this ﬁrst zone, ESA and MMPA criteria

regarding take are met, and total human-caused

removals are managed using a state-dependent

strategy. It may be possible to meet conservation

goals for subpopulations in this zone with a rela-

tively low investment in monitoring, for example,

with longer intervals between monitoring efforts.

A subpopulation would fall into the second zone

(i.e., between the upper and lower thresholds) if

the carrying capacity, population size, or intrinsic

Polar Bear Conservation Management Plan 45

IV. Conservation Management Strategy

growth rate fell below thresholds indicating that

one or more conservation criteria were not being

met (Fig. 8, yellow zone). In this zone, additional

actions are warranted, and the best combination of

actions will depend on local considerations and the

causes of decline. Potential actions include: greater

investment in monitoring of human-caused remov-

als, population size, carrying capacity, or intrinsic

growth rate; decreased interval between monitoring

efforts; increased efforts to reduce conﬂicts that

require defense-of-life and other removals besides

subsistence harvest; and reduction in the rate of

total removals, including subsistence harvest. Thus,

should a U.S. polar bear subpopulation drop below

either of the MMPA demographic criteria (mnpl or

minimum carrying capacity), additional restrictions

on all human-caused removals, including harvest,

may be warranted. It should also be considered

that natural feedback mechanisms may decrease

removal rates for a subpopulation in this zone, such

as decreased interactions between humans and polar

bears, decreased access to traditional subsistence

hunting areas, and voluntary changes in the behav-

ior of individual hunters or villages.

A subpopulation would fall into the third zone (i.e.,

below the lower threshold) if the carrying capacity,

population size, intrinsic growth rate, or other

measures indicated that the risk of extirpation

was heightened (Fig. 8, red zone). In this zone,

emergency measures should be considered to reduce

or minimize all human-caused removals, with a goal

of affording the subpopulation an increased prob-

ability of persistence. Preliminary analyses suggest

that a subpopulation size below 350 animals may

warrant concern in this regard (Science and TEK

Work Group, unpublished data), although multiple

interacting factors can affect when a declining

subpopulation enters this third zone. Furthermore,

historically smaller subpopulations (e.g., those with

smaller geographic ranges) may meet the MMPA

demographic criteria, and thus remain in the ﬁrst

zone for management purposes, at population sizes

below this threshold. Thus, this threshold should

only serve as preliminary guidance and should be

further evaluated on a subpopulation-speciﬁc basis.

If a subpopulation is managed according to this

framework for human-caused removals, we believe

that removals will not be a threat to persistence.

Thus, a subpopulation should fall into the third

zone if the primary threat has not been adequately

addressed; reduction of human-caused removals at

this point can only serve to provide a small amount

of additional time to address the primary threat.

Consistent, thorough, and coordinated monitoring

is needed to support this framework for managing

human-caused removals. The better the monitoring,

the less risk-averse the local authorities need to

be in setting annual limits for removals; that is,

good monitoring supports all of the Fundamental

Goals. Of particular importance is the reporting

of polar bear mortality itself, including reporting

of subsistence harvest, natural mortality, defense-

of-life-and-property removals, and industrial take.

Documentation of these mortalities, and where

possible, collection of samples for demographic and

health assessment, provides valuable information

for evaluating achievement of the criteria in this

plan, as well as for identifying priority actions. Such

monitoring is best undertaken using local personnel,

skills, and resources. The development of appropri-

ate protocols for reporting take may need to take

into account the local context. Local communities

may need resources from external partners to

support this reporting effort.

The details of the three-level system will, and should

be, speciﬁc to each subpopulation. The particular

criteria and thresholds that indicate transitions

between zones, and the actions to be undertaken

in each zone, will need to be developed. This Plan

offers guidance, in the form of the framework

described above, and the Implementation Team can

offer technical support. It is the vision of this Plan

that the speciﬁcs of management of subsistence

harvest and other human-caused removals be

developed at the subpopulation level by the partici-

pating co-management partners.

Conservation and recovery actions

1. Collaborate with co-management partners and others on implementation of robust and sustainable

subsistence management strategies for the Chukchi Sea and Southern Beaufort Sea subpopulations in the

context of existing agreements.

2. Develop detailed guidance, with proposed analytical methods, for designing a take-management frame-

work at the subpopulation level.

3. Maintain, improve, and support reporting protocols for all forms of human-caused mortality and for

harvest biomonitoring efforts, both within the United States and with international partners.

4. Improve communications with Alaska Native organizations and communities to ensure that hunters and

residents of rural Alaska are more meaningful partners in polar bear co-management activities.

Total cost: approximately $1,242,000 per year.

46 Polar Bear Conservation Management Plan

IV. Conservation Management Strategy

Protect denning habitat

The availability of and access to terrestrial denning

habitat is an important component of polar bear

reproduction. Collaborative processes are currently

in place to minimize effects on denning bears (e.g.,

the Incidental Take Program under the MMPA, for

industrial activities). Going forward, we will continue

those efforts with industry and others, and will work

to improve our ability to detect dens and identify

desirable denning habitat.

As sea ice declines and the availability of stable

sea ice suitable for denning decreases, terrestrial

denning habitat will become even more important

(Fischbach et al. 2007). We will work with partners

to minimize development and disturbance on barrier

islands, which provide or could provide crucial

habitat for denning, migrating, and resting and

we will work collectively to minimize and mitigate

impacts when development occurs there.

Conservation and recovery actions

1. Continue den detection, mapping, behavioral, and habitat work in polar bear habitat in the United

States.

2. Minimize development and disturbance on barrier islands (where denning habitat is most limited).

Where development occurs in polar bear habitat within the United States, work collaboratively to mitigate

loss of denning habitat.

Total cost: approximately $197,000 per year.

Minimize risk of contamination from spills

Ship trafﬁc and offshore oil and gas activities have

increased due to summer sea ice declines (Gautier

et al. 2009, Smith and Stephenson 2013), increasing

the risk to polar bears and their prey of exposure

to oil spills. Spills have the potential to harm polar

bears in numerous ways, including through impaired

thermoregulation (Hurst and Øritsland 1982, Hurst

et al. 1991), ingestion (Derocher and Stirling 1991,

Øritsland et al. 1981, St. Aubin 1990), and consump-

tion of contaminated prey (Stirling 1990). Depending

on the size, location and timing, a spill could affect a

large number of animals (Amstrup et al. 2006).

Current regulatory processes (e.g., NEPA analyses,

ESA section 7 consultations, MMPA incidental take

regulations) and industry-led plans and practices

have contributed to the absence of any major

mishaps affecting polar bears in 30 years of oil

and gas operations on the North Slope. Continued

vigilance is imperative, particularly with the opening

of new shipping lanes, the prospect of offshore oil

exploration and development, and the increased

risk of contaminant release from community tank

farms and landﬁlls along the coast. We will pursue

several avenues to minimize the risk of marine spills

and, should a spill occur, to improve the ability of

responders to minimize harm to polar bears and

their prey. Examples of speciﬁc actions include

continuing to provide feedback on oil exploration

plans and compliance documents; ensuring that

responders and companies have current information

on seasonal bear movements, aggregations, and

important habitat areas; and developing standard

operating procedures for deterrence, rescue, and

handling of oiled bears.

Conservation and recovery actions

1. Update existing oil spill modeling and scenarios; anticipate potential overlap with seasonal polar bear

movements, aggregations, and important habitats within the United States.

2. Review and comment on proposed projects and activities in polar bear habitat within the United States

(e.g., oil and gas exploration, new shipping routes and regulations, and community tank farms) to mitigate

potential adverse outcomes.

3. Develop and distribute standard operating procedures and mitigation plans for deterrence, rescue, and

handling of oiled polar bears.

Total cost: approximately $501,000 per year.

Polar Bear Conservation Management Plan 47

IV. Conservation Management Strategy

Conduct strategic monitoring and research

1. Strategic monitoring to determine if Plan goals are being met

This section focuses on strategic monitoring to

evaluate the effectiveness of this Plan. Areas of

research are identiﬁed and more details are provid-

ed in Appendix B. The monitoring actions identiﬁed

at this time are those possible with available knowl-

edge and tools, for example animal tracking using

collars or tags. Investment in additional research

is essential to improve our knowledge and identify

additional more effective and efﬁcient (and less

invasive) methods for monitoring population status

and the effectiveness of our actions. This work

requires active engagement of current and new

partners in research activities including Universi-

ties, other Federal, State, and local agencies, along

with industry and non-governmental entities.

The fundamental goals, demographic criteria, and

threats-based criteria described above clearly

state the needs for conservation and recovery, and

represent the best interpretation of available policy

guidance and scientiﬁc evidence. To address the

remaining uncertainties in the policy interpretations

and scientiﬁc evidence, an adaptive management

plan for updating and revising the conservation

and recovery criteria should be designed early in

the recovery implementation process. Some of the

components of such a plan are described in detail

below; others are identiﬁed elsewhere in the docu-

ment. One of the ﬁrst tasks of the Implementation

Team will be to prioritize these information needs.

As stated previously, the ultimate measure of

success of this Plan will be evaluated with the

fundamental criteria and performance metrics

(Table 1). As a practical matter, the speciﬁed demo-

graphic and threats-based criteria are intended to

guide conservation planning and status assessments.

These criteria are more easily measured proxies

for our fundamental goals, and can be used to track

progress toward those goals. In addition to monitor-

ing these criteria, which describe the condition of

polar bears and their environment, it is also impor-

tant to track implementation of the management

activities identiﬁed in the previous conservation and

recovery action section of this Plan. Furthermore, it

is important to evaluate whether the management

activities had the intended effect. Monitoring must

focus both on implementation (the extent to which

the plan is followed and recovery actions are taken)

and effectiveness (to what extent recovery actions

are successful and progress is made). Collectively,

monitoring the demographic and threats-based

criteria, tracking implementation of management

activities, evaluating the effect of management

activities, and continuing to reﬁne the demographic

and threats-based criteria as new information is

obtained, provide the adaptive management frame-

work necessary to meet the goals of this Plan.

This section outlines methods to monitor demo-

graphic and threats-based criteria. The ultimate

goals of monitoring are to understand the state of

the system, continue to learn about its dynamics,

detect changes including those due to management

activities, and use this information to trigger new

or additional management actions as necessary to

meet the goals of the Plan. Recovery is an iterative

process. Through careful monitoring, the data

generated and lessons learned through implement-

ing individual recovery actions feed back into

reﬁning the recovery plan and strategy.

One of the key questions regarding monitoring is

the appropriate scale. The ESA demographic and

threats-based criteria apply to each recovery unit

and the MMPA demographic criteria apply to each

subpopulation. Because of the logistical challenges

associated with monitoring outside the United

States, the focus of the monitoring actions in this

Plan is on the two subpopulations of polar bears

resident in the United States within the Polar Basin

Divergent Ecoregion. The fundamental goals will

ultimately be evaluated at the species level, which

will require international coordination.

This section provides the metrics that will be used

to monitor the Conservation Management Plan. It

is likely that the Implementation Team may identify

the need for a more detailed monitoring plan that

will specify the power of different monitoring

approaches, including use of Traditional Ecological

Knowledge, to detect change, what kinds of changes

are important (increases or decreases), and over

what time period. Traditional Ecological Knowl-

edge, for example, could be used to describe changes

that may be occurring prior to being detected by

science, and to provide insight to aspects of the

ecosystem possibly overlooked by science. Once

appropriate objectives are speciﬁed, scientists can

Conservation and recovery actions

1. Develop an adaptive management plan for updating and revising the conservation and recovery criteria.

2. Develop speciﬁc analytical methods for evaluating the ESA and MMPA Demographic Criteria.

Total cost: (included in operational costs of Implementation Team).

48 Polar Bear Conservation Management Plan

IV. Conservation Management Strategy

b. ESA demographic criteria

Monitoring Activity Data Obtained / Output

Monitor the number of subsistence hunting remov-

als in the SB subpopulation

Number of direct, lethal removals in the SB

subpopulation

Monitor the number of defense-of-life removals in

the SB subpopulation from villages, industry, and

any other causes

Monitor the number of subsistence hunting remov-

als in the CS subpopulation

Number of direct, lethal removals in the CS

subpopulation

Monitor the number of defense-of-life removals in

the CS subpopulation from villages, industry, and

any other causes

Total cost: $154,000 per year

then design monitoring that will meet the stated

needs. The Implementation Team may also identify

different or additional metrics to track progress

toward the fundamental goals.

1. The mean adult female survival rate (at a density

corresponding to mnpl and in the absence of

direct human-caused removals) in each recovery

unit is at least 93%-96%, both currently and as

projected over the next 100 years.

2. The ratio of yearlings to adult females (at a

density corresponding to mnpl) in each recovery

unit is at least 0.1-0.3, both currently and as

projected over the next 100 years.

3. The carrying capacity, distribution, and connec-

tivity in each recovery unit, both currently and as

projected over the next 100 years, are such that

the probability of persistence over 100 years is at

least 90%.

4. Total direct human-caused removals in each

recovery unit do not exceed a rate h (relative to

the subpopulation size) that maintains the popula-

tion above its mnpl relative to carrying capacity.

a. MMPA demographic criteria

Health and stability of the marine ecosystem. The

intrinsic growth rate of each subpopulation is above,

and is expected to remain above, a minimum level

that indicates the health of the marine ecosystem

is not impaired; and the carrying capacity in each

subpopulation is above, and is expected to remain

above, 70% of mean historical carrying capacity,

indicating that the stability of the marine ecosystem

is not impaired.

Maximum net productivity level. Total human-

caused removals in each subpopulation do not

exceed a rate h (relative to the subpopulation size)

that maintains the subpopulation above its maximum

net productivity level relative to carrying capacity.

Signiﬁcant functioning element in the ecosystem.

As stated previously, at this time we do not have

enough information to propose measures to

directly assess the functional role of polar bears in

their ecosystem. Instead, we offer some potential

approaches that could serve as proxies by focusing

on particular roles that polar bears play. Further

thought should be given to these approaches during

implementation of this Plan and adjustments to

monitoring should be made as appropriate.

 Energy ﬂow among trophic levels linked to

polar bears

 Behavior of prey species

 Distribution and demographics of prey

species

 Persistence and distribution of scavengers

that rely on polar bear kills (e.g., foxes)

 Availability of polar bears for subsistence

harvest

 Polar bear behavioral diversity necessary

to maintain resilience to environmental

stressors

 Polar bear densities (e.g., bears per km

) on

sea ice or land habitats at certain times of

year

 Carrying capacity and intrinsic growth rate

at the subpopulation and ecoregion level, as

estimated through hierarchical modeling of

demographic and habitat data

 Habitat measures (like ice-free months)

that could serve as a proxy for health and

stability of the ecosystem

Polar Bear Conservation Management Plan 49

IV. Conservation Management Strategy

c. ESA Threats-based criteria

Monitoring Activity Data Obtained / Output

Conduct spring capture-based and genetic sampling

work on the sea ice in the southern Beaufort

subpopulation

Adult female survival rate

Ratio of yearlings: adult females

Conduct spring capture-based and genetic sampling

work on the sea ice in the Chukchi Sea subpopula-

tion

Adult female survival rate

Ratio of yearlings: adult females

Demographic parameter estimation Index or estimate of subpopulation size, index or

estimate of subpopulation capacity for positive

growth (e.g., r

mnpl

, the per capita growth rate

at mnpl), relationships between vital rates and

environmental conditions

Develop Bayesian hierarchical estimation methods Estimates of carrying capacity

Develop ecoregion- and subpopulation-speciﬁc

demographic modeling and population viability

assessment, for the ecoregions and subpopulations

that partially fall within the United States

Projected values of demographic criteria into the

future, probability of population persistence in the

future

Total cost: approximately $1,545,000 per year

The 2008 ﬁnal listing of polar bears as threatened

under the ESA summarized the best available

scientiﬁc and commercial information regarding

threats to the polar bear. The conclusion of that

analysis was that the polar bear is threatened

throughout its range by habitat loss (i.e., sea-ice

declines). No known regulatory mechanisms in place

at the national or international level were identiﬁed

that directly and effectively address the primary

threat to polar bears—the range-wide loss of sea-ice

habitat. While not identiﬁed as factors currently

threatening polar bears, overutilization, disease

and predation, and contaminants were identiﬁed

as potential future threats as habitat loss occurs,

declining population levels are realized, and nutri-

tional stress becomes more prevalent. Given that

context, the sea ice threats-based criterion below

addresses the factor determined to be currently

threatening polar bears whereas the criterion for

human-caused removals is intended to monitor and

manage that factor to ensure it does not threaten

polar bears in the future.

Sea ice: In each recovery unit, either (a) the average

annual ice-free period is expected not to exceed

4 months over the next 100 years based on model

projections using the best available climate science,

or (b) the average annual ice-free period is expected

to stabilize at longer than 4 months over the next

100 years based on model predictions using the best

available climate science, and there is evidence that

polar bears in that recovery unit can meet ESA

Demographic Criteria 1, 2, and 3 under that longer

ice-free period.

Human-caused removals: For each recovery unit,

the total level of direct, lethal removals of polar

bears by humans, in conjunction with other factors,

does not reduce the probability of persistence below

90% over 100 years.

Additional factors of potential future concern: At

this point, the potential for disease, shipping, oil and

gas development, and oil spills to become threats

is relatively distant or low. However, recognizing

the rapidly changing Arctic environment and the

adaptive nature of this Plan, monitoring these

potential avenues of stress is warranted to an extent

that recognizes higher priorities described in this

section.

The level of human-caused removal is needed to calculate

the effect of those removals on persistence, but collect-

ing data on human-caused removals is captured in the

previous table of monitoring activity so is not repeated

here.

Monitoring Activity Data Obtained / Output

Update sea ice projections as substantial new

research, data, or tools become available

Projected duration of the ice-free period in each

recovery unit over the next 100 years

Continue analysis and monitoring to further reﬁne

and track the potential effect of human-caused

removals on persistence

Probability of persistence with and without human-

caused removals

Total cost: $10,000 per year per subpopulation

50 Polar Bear Conservation Management Plan

IV. Conservation Management Strategy

d. Other measures of achievement

As stated previously, fundamental Goals 4, 5, and 6

are not derived directly from statute, but instead

are expressions of other societal values that could be

affected by polar bear management. Performance

requirements do not need to be prescribed for these

goals (as they do for ESA recovery criteria and

MMPA conservation criteria). It will be important,

however, to address achievement of these goals,

particularly to provide an adaptive feedback loop

for improving future conservation actions. If we

are successful in managing other threats to polar

bears such that populations persist, then we will

be better positioned to successfully recognize the

nutritional and cultural traditions of Native peoples

with connections to polar bears (Fundamental Goal

4). Monitoring the MMPA Demographic Criteria

speciﬁed above requires collection of data on the

number of lethal removals of polar bears, but to

put this into context data should be collected on the

broader effort to manage human-polar bear interac-

tions and the relative success of various deterrence

strategies (Fundamental Goal 5). Finally, there

should be a qualitative assessment of our success at

achieving polar bear conservation while minimizing

restrictions to other activities, including economic

development (Fundamental Goal 6).

2. Research needs for United States polar bear subpopulations

The previous section focused on monitoring

demographic and threats-based criteria to inform

management actions and adjustments. This section

focuses on research designed to develop or reﬁne the

criteria that serve as proxies for our fundamental

goals, improve monitoring of these criteria, and

improve our understanding of the relationships (e.g.,

between sea-ice availability and vital rates) and

ecosystem dynamics that cumulatively determine

polar bear persistence. We divide research into

the following ﬁve areas: (1) population dynamics

and distribution; (2) habitat ecology; (3) health and

nutritional ecology; (4) nutritional and cultural use

of polar bears; and (5) human-polar bear interac-

tions. We brieﬂy review these areas of research and

a list of representative research projects is attached

(Appendix B). Speciﬁc priorities and cost estimates

for these areas will be developed by the Recovery

Implementation Team and Team members. We envi-

sion a dynamic and adaptive process through which

this Plan is updated to reﬂect new information, and

research planning is updated to reﬂect the living

Conservation Management Plan document. We also

envision the active engagement of current and new

partners in these activities including Universities,

other Federal, State, and local agencies along with

industry and non-governmental entities.

Population dynamics and distribution. Research in

this area is intended to improve our understanding

of the relationship between polar bears and the

environment. This research will provide insights into

how factors such as sea ice and prey abundance and

availability affect polar bear distribution and vital

rates. We have learned from research and monitor-

ing on the two polar bear subpopulations shared

by the United States that physical and biological

differences among populations may affect how polar

bears respond to habitat loss associated with climate

change, especially in the near term. Long-term

studies of subpopulation status (e.g., including vital

rates used as demographic criteria) and trends are

needed to measure progress towards persistence-

based goals. Where possible and appropriate, we

will pursue research on population dynamics and

distribution of our shared populations with our

international partners.

Habitat ecology. Under this research area, we will

study the response of polar bear subpopulations

to biotic and abiotic changes in the environment,

including intermediate effects on primary (seals)

and alternate (e.g., stranded marine mammals) prey.

This will provide an improved understanding of the

mechanistic links between habitat and demograph-

ics. Further research is also needed to understand

linkages between atmospheric concentrations of

GHG, sea ice, and polar bear resource selection and

demographics.

USFWS

Polar Bear Conservation Management Plan 51

IV. Conservation Management Strategy

Health and nutritional ecology. This research will

attempt to identify causal links between factors that

determine health and population-level processes,

which are difﬁcult to establish for marine mammals

that inhabit Arctic or subarctic ecosystems.

Nutritional and cultural use of polar bears.

Historically, native communities throughout the

coastal Arctic have relied upon polar bears as both

a nutritional and cultural resource. Research,

including through Traditional Ecological Knowledge,

may help to better understand the cultural and

nutritional signiﬁcance of polar bears to communi-

ties that have historically relied upon them, and how

climate change may affect the use of polar bears as a

renewable resource in the future.

Human-polar bear conﬂict. There is a need to

continuously improve our understanding of human-

polar bear interactions including the causes and

consequences (both positive and negative outcomes).

Understanding the factors that cause an interaction

to result in success or a conﬂict, with consequences

to humans, polar bears, or both, will provide essen-

tial feedback to evaluate the effectiveness of existing

mitigation measures.

52 Polar Bear Conservation Management Plan

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Polar Bear Conservation Management Plan 57

VI. Glossary

Allee effect. A negative population growth rate that

occurs at low population density. There are a number of

mechanisms that could give rise to this effect; in polar

bears, the most likely mechanism is difﬁculty in ﬁnding

mates (Molnár et al. 2014).

Conservation. As deﬁned under the MMPA, conservation

is “the collection and application of biological informa-

tion for the purposes of increasing and maintaining

the number of animals within species and populations

of marine mammals at their optimum sustainable

population” (16 USC §1362(2)). In this Plan, we use the

term “conservation” to refer to the activities designed

to achieve the purposes of the MMPA. Note that the

ESA also contains a deﬁnition of the term, “the use of all

methods and procedures which are necessary to bring any

endangered species or threatened species to the point at

which the measured provided pursuant to this Act are no

longer necessary (16 USC §1532(3)). To avoid confusion,

in this Plan, “conservation” is used in reference to the

MMPA and “recovery” is used in reference to the ESA.

Demographic stochasticity. Variation in demographic

rates due to the random events that happen to individual

animals. This type of variation becomes important at small

population sizes.

Distinct population segment (DPS). Under the ESA,

a “species” includes “any subspecies of ﬁsh or wildlife or

plants, and any distinct population segment of any species

of vertebrate ﬁsh or wildlife which interbreeds when

mature” (16 USC 1532(16)). Under policy guidance issued

by USFWS and NMFS (61 FR 4722–4725), three elements

should be considered in deciding whether a population

qualiﬁes as a DPS: the discreteness of the population in

relation to the rest of the species; the signiﬁcance of the

population segment to the species; and the population

segment’s status in relation to the standards for listing

under the ESA.

Ecoregion. Amstrup et al. (2008) deﬁned polar bear

ecoregions on the basis of temporal and spatial patterns

of sea-ice dynamics, observations of the patterns of polar

bear responses to these dynamics, and forecasts of future

sea-ice patterns. There are four ecoregions: the Seasonal

Ice Ecoregion (SIE), the Archipelago Ecoregion (AE), the

Polar Basin Convergent Ecoregion (PBCE), and the Polar

Basin Divergent Ecoregion (PBDE). The two subpopula-

tions found in United States territory both fall within the

PBDE.

Endangered. Under the ESA, an endangered species is

“any species which is in danger of extinction throughout

all or a signiﬁcant portion of its range” (16 USC 1532(6)).

This classiﬁcation represents the highest level of concern

for a species under the ESA.

Health of the marine ecosystem. In the MMPA,

Congress found that the “primary objective of [marine

mammal] management should be to maintain the health

and stability of the marine ecosystem” (16 USC 1361(6)).

The term “health of the marine ecosystem” is not

otherwise deﬁned, although the deﬁnition of OSP makes

reference to it. In this Plan, we assume that the health of

the marine ecosystem is reﬂected in its ability to support

marine mammals, and use the intrinsic growth rate of a

polar bear subpopulation as its measure.

Human-caused removal rate. In this Plan, under MMPA

Demographic Criterion 2, we deﬁne a satisfactory human-

caused removal rate as a ﬁxed-rate removal of polar bears,

h, that maintains a subpopulation above its mnpl. Under

this deﬁnition, continued take is possible even when the

carrying capacity and the population size are declining,

provided the take is adjusted annually to account for

the change in the population size, and the population

size at all times is maintained above its mnpl relative

to carrying capacity. This deﬁnition is offered for the

broader purposes of this Plan, but does not preclude more

protective criteria being used for speciﬁc subpopulations

(e.g., “sustainable take” under the United States-Russia

bilateral agreement for the Chukchi Sea subpopulation).

Inbreeding depression. A negative consequence of small

population size. Inbreeding depression can arise through

breeding of related individuals, the consequent reduction

in genetic diversity, and the expression of deleterious

recessive genes.

Intrinsic population growth rate. The rate of growth

of a population in the absence of human-caused removals

and at a low density relative to the carrying capacity.

This growth rate is a measure of resilience—the higher

the intrinsic rate of growth, the quicker a population can

rebound from a short-term impact.

Maximum net productivity level (mnpl and MNPL).

The population size that results in “the greatest net

annual increment in population numbers or biomass

resulting from additions to the population due to repro-

duction and/or growth less losses due to natural mortality”

(50 CFR 403.02).

Optimum sustainable population (OSP). As deﬁned

in the MMPA, OSP is “the number of animals which will

result in the maximum productivity of the population or

the species, keeping in mind the carrying capacity of the

habitat and the health of the ecosystem of which they form

a constituent element” (16 USC 1362(9)). Congressional

reports and agency policies have further clariﬁed that

OSP represents a range of population sizes between

the maximum net productivity level and the carrying

capacity of the ecosystem. One of the primary purposes

of the MMPA is to restore and maintain marine mammal

populations at OSP.

VI. GLOSSARY

58 Polar Bear Conservation Management Plan

VI. Glossary

Population. A group of animals in the same taxon below

the subspeciﬁc level, in common spatial arrangement that

interbreed when mature (50 CFR 17.3). Speciﬁc popula-

tions have not been identiﬁed for polar bears. The smallest

groupings recognized by the Polar Bear Specialist Group

are referred to as “subpopulations.” In this Plan, we avoid

using the term “population,” except as a generic term to

refer to a group of polar bears.

Recovery. Under the ESA, the Secretary (of the Interior

or of Commerce) is required to develop recovery plans

“for the conservation and survival of endangered species

and threatened species listed pursuant to this section” (16

USC 1533(f)(1)). The term “recovery” is not deﬁned in the

ESA, but is interpreted to be similar to “conservation”

under the ESA (see above), namely, improvement in the

status of a listed species to the point at which listing is no

longer appropriate under the criteria set out in section

4(a)(1) of the ESA (50 CFR 402.02). We use the term

“recovery” to refer to the purposes of this Plan under the

ESA (and “conservation” to refer to the purposes of this

Plan under the MMPA).

Recovery unit. Under the ESA, “a special unit of the

listed entity that is geographically or otherwise identiﬁ-

able and is essential to the recovery of the entire listed

entity, i.e., recovery units are individually necessary to

conserve genetic robustness, demographic robustness,

important life history stages, or some other feature

necessary for long-term sustainability of the entire listed

entity” (NMFS and USFWS 2010). In this Plan, the four

polar bear ecoregions are identiﬁed as recovery units.

Signiﬁcant functioning element of the ecosystem. In

the MMPA, Congress found that “species and population

stocks should not be permitted to diminish beyond the

point at which they cease to be a signiﬁcant functioning

element in the ecosystem of which they are a part, and,

consistent with this major objective, they should not be

permitted to diminish below their optimum sustainable

population” (16 USC 1361(2)). The term is not otherwise

deﬁned. In this Plan, the maintenance of polar bears as

a signiﬁcant functioning element of the Arctic marine

ecosystem is an important conservation goal. As a top

predator, polar bears have a signiﬁcant role in the energy

ﬂow in the ecosystem, and in the distribution and behavior

of prey species. Potential measures for their function in

the ecosystem are proposed in the Plan.

Stability of the marine ecosystem. In the MMPA,

Congress found that the “primary objective of [marine

mammal] management should be to maintain the health

and stability of the marine ecosystem” (16 USC 1361(6)).

The term “stability of the marine ecosystem” is not other-

wise deﬁned. In this Plan, we assume that the stability of

the marine ecosystem is reﬂected in its ability to support

marine mammals, and use the carrying capacity of a polar

bear subpopulation as its measure.

Stock. Under the MMPA, a stock is “a group of marine

mammals of the same species or smaller taxa in a common

spatial arrangement, that interbreed when mature” (16

USC 1362(11)). The Southern Beaufort Sea and Chukchi

Sea polar bear subpopulations have been identiﬁed as

stocks under the MMPA. In this Plan, we assume that all

subpopulations could be identiﬁed as stocks.

Subpopulation. The Polar Bear Specialist Group has

identiﬁed 19 relatively discrete “subpopulations” of polar

bears (Fig. 1). In this Plan, we reserve this term to refer

speciﬁcally to those groupings of polar bears.

Take. Under the MMPA, “take” means “to harass, hunt,

capture, or kill, or attempt to harass, hunt, capture, or

kill any marine mammal” (16 USC 1362(13)). Under

the ESA, “take” means “to harass, harm, pursue, hunt,

shoot, wound, kill, trap, capture, or collect, or to attempt

to engage in any such conduct” (16 USC 1532(19)). This

Plan primarily addresses lethal take of polar bears, and is

less speciﬁc about non-lethal take. Thus, for the purpose

of brevity, unless otherwise noted, “take” refers to all

anthropogenic lethal removals of polar bears, but the

broader deﬁnitions remain the legal standard.

Threatened. Under the ESA, a threatened species is “any

species which is likely to become an endangered species

within the foreseeable future throughout all or a signiﬁ-

cant portion of its range” (16 USC 1532(20)). Polar bears

were classiﬁed as threatened under the ESA in 2008.

Traditional ecological knowledge (TEK). The cumula-

tive body of knowledge about local natural resources

accumulated by indigenous, aboriginal, or local people and

often passed down through generations through practice

and oral traditions. This Plan recognizes that there is an

appropriate role for TEK in science and management of

polar bears, just as there is an appropriate role for the

empirical methods of Western science; indeed, these sets

of knowledge can often enhance each other.

Polar Bear Conservation Management Plan 59

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Polar Bear Conservation Management Plan 61

Appendix A—Background

APPENDIX A—BACKGROUND

Brief Overview/Species Status

Polar bears (Ursus maritimus) occur in 19 relatively

discrete subpopulations (Plan Fig. 1) throughout

the seasonally and permanently ice-covered marine

waters of the northern hemisphere (Arctic and

Subarctic), in Canada, Denmark (Greenland),

Norway, Russia and the United States (U.S.).

The status of each of these subpopulations varies

(Polar Bear Specialists Group Status Table; http://

pbsg.npolar.no/en/status/status-table.html). The

U.S. contains portions of two subpopulations: the

Chukchi Sea (CS) (also called the Alaska-Chukotka

subpopulation in the U.S.–Russia Bilateral Agree-

ment) and the Southern Beaufort Sea (SB) subpopu-

lation. The polar bear was listed as a threatened

species under the U.S. Endangered Species Act of

1973, as amended (16 USC 1531 et seq.)(ESA) on

May 15, 2008 (73 FR 28212). The total circumpolar

population is estimated to be 26,000 (95% CI =

22,000 – 31,000) polar bears (Wiig et al. 2015).

Species Biology and Life History

Physical characteristics. Polar bears are the largest

living bear species (Demaster and Stirling 1981), and

are characterized by large body size, a stocky form,

and have a longer neck and proportionally smaller

head than other ursids. Their hair is non-pigmented.

Fur color varies between white, yellow, grey, or

almost brown, and is affected by oxidation, i.e.

exposure to the air, light conditions, and soiling or

staining due to contact with fats obtained from prey

items (Amstrup 2003). They are sexually dimorphic;

females weigh 181 to 317 kilograms (kg) (400 to 700

pounds (lbs) and males up to 654 kg (1,440 lbs).

Adaptations. Polar bears evolved in Arctic sea ice

habitats and are evolutionarily well adapted to this

habitat. Their unique physical adaptations include:

(1) non-pigmented pelage with water-repellent

guard hairs and dense underfur; (2) a short, furred

snout; (3) small ears with reduced surface area;

(4) teeth specialized for a carnivorous rather than

an omnivorous diet; and (5) feet with tiny papillae

on the underside, which increase traction on ice

(Stirling 1988). In addition, they have large, paddle-

like feet (Stirling 1988), and claws that are shorter

and more strongly curved than brown bear (Ursus

arctos) claws, and larger and heavier than those of

black bears (Ursus americanus) (Amstrup 2003)

used mainly for clutching prey.

Breeding and reproduction. Polar bears are a

K-selected species, characterized by late sexual

maturity, small litter sizes, and extended parental

investment in raising young. All of these factors

contribute to the species’ low reproductive rate

(Amstrup 2003). Females generally mature and

breed for the ﬁrst time at 4 or 5 years and give

birth at 5 or 6 years of age. Litters of two cubs are

most common, but 3-cub litters are seen on occasion

across the Arctic (Amstrup 2003). The minimum

reproductive interval for adult females is three

years.

Females enter a prolonged estrus between March

and June, when breeding occurs. Though bears

ovulate in the spring, implantation is delayed until

autumn. The timing of implantation, and therefore

the timing of birth, likely depends on body condi-

tion of the female, which is determined by many

environmental factors. When foraging conditions

are difﬁcult, polar bears may “defer” reproduction

in favor of survival (Derocher and Stirling 1992,

Eberhardt 2002). Pregnant females that spend the

late summer on land prior to denning may not feed

for eight months (Watts and Hansen 1987) which

coincides with the time when the female gives birth

and nourishes new cubs.

Altricial, newborn polar bears have fur, but are

blind, and weigh only 0.6 kg (1.3 lb) (Blix and

Lentfer 1979). Cubs grow rapidly, and may weigh

10 to 12 kg (22 to 26 lbs) by the time they emerge

from the den in the spring. Young bears will stay

with their mothers until weaning, which occurs most

commonly in early spring when the cubs are 2 1/2

years old. Female bears are available to breed again

after their cubs are weaned.

Survival. Polar bears are long-lived and are not

generally susceptible to disease or parasites. Due to

extended maternal care of young and low reproduc-

tive rates, polar bears require high adult survival

rates, particularly females, to maintain population

levels (Eberhardt 1985; Amstrup and Durner 1995).

Survival rates are generally age dependent, with

cubs-of-the-year having the lowest rates and prime

age adults (prime reproductive years are between

approximately 5 and 20 years of age) having survival

rates that can exceed 90 percent (Regehr et al.

2007b). Survival rates exceeding 90 percent for adult

females are essential to sustain polar bear popula-

tions (Amstrup and Durner 1995).

New studies (Rode et al. 2010a, 2014b) conducted on

the SB subpopulation are consistent with previous

ﬁndings (Regehr et al. 2006) which concluded

that declines in body size, body condition, and

recruitment in recent decades were associated with

declining sea ice availability. Additionally, Regehr et

al. (2010) suggested several years of reduced sea ice

in the mid-2000s were associated with low breeding

62 Polar Bear Conservation Management Plan

Appendix A—Background

probability and survival, leading to negative popula-

tion growth rate.

Hunter et al. (2010) used the relationship between

sea ice and vital rates estimated during the period

2001–2006 to project the long-term status and

survival of the SB subpopulation under future

sea ice conditions as forecasted by global climate

models. Their models suggested a high probability

of signiﬁcant population declines in the 21

century.

Changes in body condition have been shown to affect

bear survival and reproduction, which in turn, can

have population-level effects (Regehr et al. 2010,

Rode et al. 2010a). Survival of polar bear cubs-of-

the-year has been directly linked to their weight

and the weight of their mothers, with lower weights

resulting in reduced survival (Derocher and Stirling

1996; Stirling et al. 1999). Changes in body condition

indices were documented in the Western Hudson

Bay subpopulation before a statistically signiﬁcant

decline in that subpopulation was documented

(Regehr et al. 2007a). Thus, changes in these indices

may serve as an “early warning” that signal a

reduction in survival and imminent subpopulation

declines.

For the SB subpopulation, Bromaghin et al. (2015)

analyzed demographic data through 2010, and found

similar evidence to Regehr et al. (2010) for low

survival of all sex and age classes of polar bears in

the mid-2000s. However, Bromaghin et al. (2015)

also found that survival of most sex and age classes

of polar bears in the SB population increased during

the years 2007–2010, despite continued declines in

the availability of sea ice.

Feeding. Polar bears are top predators in the

Arctic marine ecosystem. Adult polar bears need

to consume approximately 2 kg (4.4 lbs) of fat per

day to survive (Stirling 1988). They prey heavily on

ice-seals, principally ringed seals (Phoca hispida),

and to a lesser extent, bearded seals (Erignathus

barbatus). Bears occasionally take larger animals,

such as walruses (Odobenus rosmarus) and belugas

(Delphinapterus leucas) (Kiliaan and Stirling 1978).

Research in the Canadian Arctic suggests that, in

some areas and under some conditions, terrestrial

prey other than seals or carrion may be able to

sustain polar bears when seals are unavailable

(Stirling and Øritsland 1995; Smith et al. 2010;

Gormezano and Rockwell 2013; Iles et al. 2013).

In addition, polar bears are opportunistic feeders

and when conﬁned to land for long periods, they

will also consume plants and other terrestrial foods

(Russell 1975; Derocher et al. 1993; Smith et al.

2010, Gormezano and Rockwell 2013). However,

new studies (Rode et al. 2010b, 2014, 2015a) conﬁrm

previous ﬁndings (Derocher et al. 2004) that the

relevance of terrestrial foods, such as avian eggs,

to the long-term welfare of polar bears is limited

by their patchy availability and relatively low

nutritional content.

Population Delineation and Distribution

Delineation. Five countries share management

responsibilities for polar bears, including Canada,

Greenland (an autonomous country within the

Danish realm), Norway, Russia, and the United

States (the polar bear Range States). Both the 2008

listing and this 5-year review are based on the Polar

Bear Specialist Group (PBSG) delineation (Plan

Figure 1) which usually, but not always, reﬂects

ecological boundaries. In some cases, boundaries are

practical delineations for management purposes.

The Chukchi Sea subpopulation is shared by the

U.S. and Russia. The boundaries of this subpopula-

tion are described differently in the Agreement

between the United States of America and the

Russian Federation on the Conservation and

Management of the Alaska—Chukotka Polar Bear

Population” (Bilateral Agreement) and in PBSG

publications. The Bilateral Agreement describes the

CS subpopulation within a line extending north from

the mouth of the Kolyma River and on the east by

a line extending north from Point Barrow (Obbard

et al. 2010). However, the PBSG describes the

northeastern boundary near Icy Cape, Alaska to a

western boundary near Chauniskaya Bay, Russia, in

the Eastern Siberian Sea (Obbard et al. 2010).

The Southern Beaufort Sea subpopulation is shared

by the U.S. and Canada. The western boundary

is near Icy Cape, Alaska (Obbard et al. 2010). The

eastern boundary was originally determined to be

south of Banks Island and east of the Baillie Islands,

Canada. Recently, the eastern boundary between

the SB and Northern Beaufort subpopulation (NB)

has been moved westward, near the community

of Tuktoyaktuk, Northwest Territories, Canada

(WMAC 2011). The Canadian Inuvialuit Game Coun-

cil and the North Slope Borough of Alaska adjusted

the boundary to 133° W to better align management

boundaries with the current distribution of polar

bears in this region which was based on radio-

tracking data. The shift in the boundary is currently

being implemented by the agencies involved in

managing the SB and NB subpopulations. However,

the new boundary change is currently not recog-

nized by the PBSG.

Distribution. Polar bear subpopulations have

been further classiﬁed as occurring in one of four

ecoregions (Plan Figure 2; Amstrup et al. 2008)

based on the spatial and temporal dynamics of sea

ice in the subpopulation’s range. Subpopulations

classiﬁed as occurring in the Seasonal Ice Ecoregion

share the characteristic that the sea ice in their

range fully melts in the summer, during which time

Polar Bear Conservation Management Plan 63

Appendix A—Background

bears are forced on shore for extended periods until

the sea ice reforms. Subpopulations occurring in

the Archipelago Ecoregion are characterized as

having heavy annual and multi-year sea ice that ﬁlls

the channels between the Canadian Arctic Islands.

Bears in this ecoregion remain on the sea ice

throughout the year. The Divergent Ice Ecoregion is

characterized by the formation of annual sea ice that

is advected towards the polar basin. Conversely, the

Convergent Ice Ecoregion is characterized annual

sea ice that converges towards shoreline allowing

bears to access nearshore ice year-round.

Population Size Estimates and Trends

Abundance. Accurate estimates of polar bear

subpopulation sizes and trends are difﬁcult to

obtain due to the species’ low densities, the vast

and inaccessible nature of their sea ice habitat, the

movement of bears across international boundaries,

and limited budgets (USFWS 2010a, 2010b). The

global population is estimated to be approximately

26,000 (95% CI = 22,000 to 31,000) throughout the

circumpolar arctic (Wiig et al. 2015).

In 2008, of the 19 subpopulations, and excluding the

Arctic Basin, two subpopulations were reported to

be increasing (M’Clintock Channel and Viscount

Melville), ﬁve subpopulations were reported as

stable (Foxe Basin, Gulf of Boothia, Lancaster

Sound, Northern Beaufort Sea, Southern Hudson

Bay), ﬁve subpopulations were described as declin-

ing (Bafﬁn Bay, Kane Basin, Norwegian Bay, SB,

Western Hudson Bay), and six were reported as

data deﬁcient (Barents Sea, CS, Davis Strait, East

Greenland, Kara Sea, and Laptev Sea) (Aars et al.

2006).

Since listing (73 FR 28212, May 15, 2008),

international efforts have been undertaken to more

accurately quantify polar bear subpopulations in

order to continue to assess the threats of climate

change on the species. While the type, precision,

and time span of data used to estimate trends varies

among subpopulations (Wiig et al. 2015), information

reported in 2014 (PBSG 2015) now suggests that one

subpopulation (M’Clintock Channel) is increasing;

six subpopulations are stable (Davis Strait, Foxe

Basin, Gulf of Boothia, Northern Beaufort Sea,

Southern Hudson Bay, and Western Hudson Bay),

three subpopulations are declining (Bafﬁn Bay,

Kane Basin, and SB) and 9 are data deﬁcient (Arctic

Basin, Barents Sea, CS, East Greenland, Kara Sea,

Lancaster Sound, Laptev Sea, Norwegian Bay,

and Viscount Melville Sound). (PBSG 2015; http://

pbsg.npolar.no/en/status/status-table.html). Since

2008, only the Western Hudson Bay subpopulation

has shown a positive change in trend (i.e., from

“declining” to “stable”), while the Viscount Melville

subpopulation changed from “increasing” to “data

deﬁcient” during the same period. For the remaining

17 subpopulations, trends either remain unchanged

since the time of listing or lack sufﬁcient data for

assessment.

Chukchi Sea subpopulation. Reliable estimates of

subpopulation size or status are not available for

the Chukchi Sea subpopulation. The most recent

quantitative estimate of the size of this subpopula-

tion was 2,000–5,000 polar bears (Belikov 1992),

based on incomplete denning surveys in Russian

portions of the Chukchi Sea where most of the

subpopulation is believed to den (Belikov 1980). In

2005, expert opinion among the PBSG members

was that the subpopulation had around 2,000 bears

(Aars et al. 2006). This estimate was derived by

extrapolating the earlier estimate of Belikov (1992).

At the time of the ESA listing in 2008, the PBSG

reported this subpopulation at approximately 2,000

animals. Subsequently, the PBSG listed the size of

this subpopulation as “unknown,” and currently lists

the CS subpopulation trend as “data deﬁcient.”

Southern Beaufort Sea subpopulation. The South-

ern Beaufort Sea subpopulation had an estimated

population size of approximately 900 bears in 2010

(Bromaghin et al. 2015). This represents a signiﬁ-

cant reduction from previous estimates of approxi-

mately 1,800 in 1986 (Amstrup et al. 1986), and 1,526

in 2006 (Regehr et al. 2006). In addition, analyses of

over 20 years of data on the size and body condition

of bears in this subpopulation demonstrated declines

for most sex and age classes and signiﬁcant negative

relationships between annual sea ice availability

and body condition (Rode et al. 2010a). These lines

of evidence suggest that the Southern Beaufort Sea

subpopulation is currently declining due to sea ice

loss.

Habitat Characteristics and Needs

Pack ice is the primary summer habitat for polar

bears in the U.S. (Durner et al. 2009 Rode et al.

2015b; Atwood et al. 2016b). Polar bears depend on

sea ice as a platform from which to hunt and feed; to

seek mates, breed, and den; to travel to terrestrial

maternity denning areas; and to make long-distance

movements (Stirling and Derocher 1993). Polar

bears prefer certain sea-ice stages, concentrations,

forms, and deformation types (Arthur et al. 1996;

Mauritzen et al. 2001; Durner et al. 2009; Wilson et

al. 2014), and have been shown to prefer the ﬂoe ice

edge, stable shore-fast ice with drifts, and moving

ice (Stirling et al. 1993).

Movements. Polar bear movements are closely tied

to seasonal dynamics of sea-ice extent as it retreats

northward during summer melt and advances

southward during autumn freeze. When the annual

sea ice begins to form in shallower water over the

64 Polar Bear Conservation Management Plan

Appendix A—Background

continental shelf, polar bears that retreated north

of the continental shelf during summer return to

shallower shelf waters where seal densities are

higher (Durner et al. 2009).

Access to prey. The formation and movement

patterns of sea ice strongly inﬂuence the distribu-

tion and accessibility of ringed and bearded seals

(Frost et al. 2004; Ferguson et al. 2005; Cameron

et al. 2010). The shore-fast ice zone, where ringed

seals construct subnivean (in or under the snow)

birth lairs for pupping, is also an important foraging

habitat during spring (Stirling et al. 1993). Shore-

fast ice is used by polar bears for feeding on seal

pups, for movement, and occasionally for maternity

denning (Stirling et al. 1993). In protected bays and

lagoons, shore-fast ice typically forms in autumn and

remains stationary throughout winter. Shore-fast ice

usually occurs in a narrow belt along the coast and

melts in the summer.

During the winter and spring, when energetic

demands are the greatest, nearshore lead systems

(i.e., cracks in the ice where bears can hunt

hauled-out seals) and polynyas (areas of open sea

surrounded by sea ice) are important for seals,

and are thus important foraging habitat for polar

bears. Polar bears in the SB are thought to reach

their peak weights during autumn and early winter

(Durner and Amstrup 1996). Thus, availability and

accessibility of prey during this time may be critical

for survival through the winter months.

Breeding. Polar bears also depend on sea ice as

a habitat to seek mates and breed (Stirling and

Derocher 1993). Breeding occurs in spring, between

March and June (Schliebe et al. 2006). In the

Southern Beaufort Sea, the probability that adult

females will survive and produce cubs-of-the-year is

negatively correlated with ice-free periods over the

continental shelf (Regehr et al. 2007b).

In addition, the variable nature of sea ice results in

an ever-changing distribution of suitable habitat for

polar bears, and eliminates any beneﬁt to defending

individual territories (Schliebe et al. 2006). Males

must be free of the need to defend territories if they

are to maximize their potential for ﬁnding mates

each year (Ramsay and Stirling 1986, Schliebe et al.

2006).

Denning. Throughout the polar bear’s range, most

pregnant females excavate dens in snow drifts

located on land in the autumn and early winter

period (Ramsay and Stirling 1990; Amstrup and

Gardner 1994), near the coastline (Durner et

al. 2010; Andersen et al. 2012), or, in the case of

portions of the SB subpopulation, in snow drifts on

pack and shore-fast ice. The key characteristic of all

denning habitat is topographic features that catch

snow on their leeward side in the autumn and early

winter as successful denning requires accumulation

of sufﬁcient snow for den construction and mainte-

nance (Durner et al. 2003; Liston et al. 2015). Liston

et al. (2015) suggested that polar bears need snow

drifts that are at least 1.5 meters deep to success-

fully maintain a maternity den throughout the

denning season. In some areas, the majority of polar

bear denning occurs in core areas (Harington 1968;

Stishov 1991; Ovsyanikov 2005), which show high

use over time while in other portions of the species’

range, polar bears den in a more diffuse pattern,

with dens scattered over larger areas at lower

density (Stirling and Andriashek 1992; Amstrup and

Gardner 1994; Ferguson et al. 2000).

In Alaska, most polar bear dens occur relatively

near the coast along the coastal bluffs and river-

banks of the mainland, on barrier islands, or on

the drifting pack ice (Amstrup and Gardner 1994;

Amstrup 2003; Durner et al. 2003, 2006, 2010, 2013;

USFWS and USGS unpublished data). Denning

areas on the North Slope of Alaska are in relatively

ﬂat topography (Durner et al. 2003). Currently,

approximately 37% (Fischbach et al. 2007) and 10%

(Rode el al. 2015b) of pregnant females den on ice in

the SB and CS subpopulations, respectively.

Some habitat suitable for denning has been mapped

on the North Slope (Durner et al. 2001, 2006, 2013;

Blank 2013). The primary denning areas for the

CS subpopulation occur on Wrangel Island, Russia,

where up to 200 bears per year have denned annu-

ally and the northeastern coast of the Chukotka

Peninsula, Russia (Stishov 1991; Ovsyanikov 2005;

Obbard et al. 2010).

Threats Assessment/Reasons for Listing

under the ESA

The primary threat to polar bears is the loss of sea

ice habitat due to climate change (USFWS 2008).

Polar bears evolved over thousands of years to life

in a sea ice environment. They depend on the sea

ice-dominated ecosystem to support essential life

functions. The sea ice ecosystem supports ringed

seals, primary prey for polar bears, and other

marine mammals that are a part of their prey

base (Stirling and Archibald 1977; Smith 1980;

Smith 1985, Iverson et al. 2006). New information

continues to support that polar bears rely heavily

on sea ice for essential life functions (Wilson et al.

2014). Further, there is no new information available

suggesting that the threat of climate change has

been reduced.

Additional details regarding the threats and stressors

described herein can be found in the Polar Bear Status

5-Year Review: Summary and Evaluation (USFWS

2017).

Polar Bear Conservation Management Plan 65

Appendix A—Background

Sea ice is rapidly thinning and retreating through-

out the Arctic. Ice conditions that affect polar bear

habitat include: (1) fragmentation of sea ice; (2) a

dramatic increase in the extent of open water areas

seasonally; (3) reduction in the extent and area of

sea ice in all seasons; (4) retraction of sea ice away

from productive continental shelf areas throughout

the polar basin; (5) reduction of the amount of

heavier and more stable multi-year ice; and (6)

declining thickness and quality of shore-fast ice,

if it restricts access to seals. These combined and

interrelated events change the extent and quality

of sea ice during all seasons, but particularly during

the spring-summer period.

Climate change will continue to affect Arctic sea ice

for the foreseeable future. A further review of new

information since 2008 indicates that climate change,

resulting in the loss of sea ice habitat for polar bears

continues to be the primary threat to the species.

Due to the long persistence time of certain green-

house gases (GHGs) in the atmosphere, the current

and projected patterns of GHG emissions over the

next few decades and interactions among climate

processes, climate changes over the next 40–50

years are already largely set (IPCC 2007; Overland

and Wang 2007, 2013). Climate change effects on

sea ice and polar bears will continue during this

time and likely further into the future (IPCC 2014;

Atwood et al. 2016a).

The ultimate effect will be that polar bear subpopu-

lations will decline or continue to decline. With a

diminished sea ice platform, bear distribution and

seasonal onshore abundance will change. Not all

subpopulations will be affected evenly in the level,

rate, and timing of effects (Atwood et al. 2016a).

Below, we discuss the various threats that have

been identiﬁed, organized by the ESA listing factors

(section 4(a)(1)) addressed in the Final Rule. In addi-

tion to the factors identiﬁed in the listing, additional

threats were investigated during development of

this Plan.

A. The present or threatened destruction,

modiﬁcation, or curtailment of the species’

habitat or range

A.1. Loss of access to prey

Without sea ice, polar bears lack a platform that

allows access to ice seal prey. Longer melt seasons

and reduced summer ice extent will likely force

bears to increase use of habitats where hunting

success will decrease (Derocher et al. 2004; Stirling

and Parkinson 2006). Highly-selected summer sea

ice habitat by polar bears in the CS subpopulation

has declined by 75% in the past 30 year (Wilson et

al. 2016). Once sea ice concentration drops below

50 percent, polar bears have been documented

to quickly abandon sea ice for land, where access

to their primary prey is almost entirely absent.

Bears may also retreat northward with the more

consolidated pack ice over the polar basin, which

may be less productive foraging habitat. The

northward retreat is most likely related to reduced

hunting success in broken ice with signiﬁcant open

water and need to reduce energetic costs once

prey availability and food intake drops below some

threshold (Derocher et al. 2004, p. 167; Stirling et

al. 1999, pp. 302–303). A recent study (Ware et al.

in review) found that polar bears are increasingly

found on ice over less productive waters in summer,

with activity levels indicating that they are not

hunting. Similarly, Whiteman et al. (2015) found that

bears summering on sea ice had similar metabolic

rates to those on land, indicative of fasting. During

summer, ice seals typically occur in open water and

therefore are virtually inaccessible to polar bears

(Harwood and Stirling 1992) although bears have

rarely been reported to capture ringed seals in open

water (Furnell and Oolooyuk 1980). Thus, hunting

in ice-free water will not compensate for the loss of

sea ice and the hunting opportunities it affords polar

bears (Stirling and Derocher 1993; Derocher et al.

2004). Additionally, Rode et al. (2010a) demonstrated

that available terrestrial food resources are likely

inadequate to offset the nutritional consequences of

an extended ice-free period.

Reduced duration of sea ice over shallow, productive

waters of the continental shelf is likely to have

signiﬁcant impacts on the polar bears’ ability

to access prey, and continued declines in sea ice

duration are expected in the future (Durner et al.

2009, Castro de la Guardia et al. 2013, Hamilton et

al. 2014). Polar bears have two options to respond to

these changes, 1) remain on the sea ice as it moves

over less productive waters, or 2) move to land. In

both instances, polar bears are likely to ﬁnd limited

prey items and employ similar energy saving strate-

gies (Whiteman et al. 2015). While observations

exist of polar bears eating terrestrial-based foods

(e.g., Rockwell and Gormezano 2009), the general

consensus is that these food items are unlikely to

compensate for lost hunting opportunities while on

the sea ice (Rode et al. 2015b); with rare exceptions

(e.g., Miller et al. 2015, Rogers et al. 2015, Whiteman

et al. 2015). Further, Rode et al. (2010a) demonstrat-

ed that available terrestrial food resources are likely

inadequate to offset the nutritional consequences of

an extended ice-free period.

Reduced access to preferred prey (i.e., ice seals;

Thiemann et al. 2008) is therefore likely to have

demographic effects on polar bears. For example,

in the SB subpopulation, the period when sea ice is

66 Polar Bear Conservation Management Plan

Appendix A—Background

over the continental shelf has decreased signiﬁcantly

over the past decade, resulting in reduced body

mass and productivity (Rode et al. 2010a; Rode

et al. 2014b) and likely reduced population size

(Bromaghin et al. 2015). It should be noted, however,

that researchers have documented demographic

effects of sea ice loss in only a few of the 19 polar

bear subpopulations (Regehr et al. 2007b; Rode et al.

2012). This is highlighted by Rode et al. (2014) who

found that even though sea ice loss during summer

had been substantial in the Chukchi Sea, polar bears

in that subpopulation did not exhibit concomitant

declines in body mass or productivity.

A.2. Increased movements, energy expenditure

The best scientiﬁc data available suggest that polar

bears are inefﬁcient moving on land and expend

approximately twice the average energy when

walking compared to other mammals (Best 1982;

Hurst 1982). Increased rate and extent of sea ice

movements will require polar bears to expend

additional energy to maintain their position near

preferred habitats (Mauritzen et al. 2003). This

may be an especially important consideration for

females with small cubs (Durner et al. 2010), who

have higher energetic demands due to lactation

(Gittleman and Thompson 1988; Ramsay and

Dunbrack 1986). As movement of sea ice increases

and areas of unconsolidated ice also increase, some

bears are likely to lose contact with the main body

of ice and drift into unsuitable habitat from which it

may be difﬁcult to return (Sahanatien et al. 2012).

The increased energetic costs to polar bears from

increased movements are likely to result in reduced

body weight and condition, and a corresponding

reduction in survival and recruitment rates (Regehr

et al. 2010, Rode et al. 2010a).

Diminished sea ice cover not only increases areas

of open water across which polar bears must swim,

but may inﬂuence the size of wave action. These

may result in increases in bear mortality associated

with swimming long distances (Monnett and Gleason

2006; Durner et al. 2011; Pagano et al. 2012). In

addition, diminished sea ice cover may result in

hypothermia for young cubs that are forced to

swim for longer periods than at present, although

behavioral mechanisms might exist to reduce the

probability of this occurring (Aars and Plumb 2010).

A.3. Redistribution of polar bears to where they are

more vulnerable to impacts

The continued retraction and fragmentation of

sea ice habitats that is projected to occur will alter

previous habitat use patterns seasonally and region-

ally. Recent studies indicate that polar bear move-

ments and seasonal ﬁdelity to certain habitat areas

are changing and that these changes are strongly

correlated with simultaneous changes in sea ice

(Atwood et al. 2016b, Rode et al. 2015b, Wilson et

al. 2016). These changes have been documented for

a number of polar bear subpopulations, with the

potential for large-scale shifts in distribution by the

end of the 21st century (Durner et al. 2009).

Gleason and Rode (2009) noted a greater number

of bears in open water of the southern Beaufort

Sea and on land during surveys in 1997–2005, when

sea ice was often absent from their study area,

compared to 1979–1996 surveys, when sea ice was

a predominant habitat in the area. Schliebe et al.

(2008) determined that the number of bears on land

in the southern Beaufort Sea region between 2000

and 2005 was higher during years when sea ice

retreated further offshore. Their results suggest

that a trend of increasing distance between land

and sea ice over time would be associated with an

increasing number of bears on shore and/or an

increase in the duration of time they spend there.

Changes in movements and seasonal distributions

caused by climate change can affect polar bear

nutrition and body condition (Stirling and Derocher

2012). In Western Hudson Bay, sea ice break-up

now occurs approximately 2.5 weeks earlier than

it did 30 years ago because of increasing spring

temperatures (Stirling et al. 1999; Stirling and

Parkinson 2006) which is also correlated with when

female bears come ashore and when they are able

to return to the ice (Cherry et al. 2013). Similarly,

changes in summer sea ice conditions has resulted

in an increase in the duration of time spent on

shore during the summer, and the proportion of

the population using shore in both the SB and CS

subpopulations (Rode et al. 2015b, Atwood et al.

2016b). Rode et al. (2015b) also demonstrated the

changes in sea ice dynamics has likely resulted in

a shift in land use during summer from a mix of

coastal use in Alaska and Russia before sea ice loss,

to almost exclusive coastal use in Russia after sea ice

loss.

Declining reproductive rates, subadult survival,

and body mass (weights) have occurred because

of longer fasting periods on land resulting from

progressively earlier break-ups (Stirling et al. 1999;

Derocher et al. 2004). In the Western Hudson Bay

(WH) subpopulation, the sea ice-related declines in

vital rates have led to reduced population trends and

reduced abundance (Regehr et al. 2007a). Similar

ﬁndings have occurred in other areas. Rode et al.

(2010a) suggested that declining sea ice has resulted

in reduced body size and reproductive rate within

the SB subpopulation. They also found that reduced

availability of sea ice habitat was correlated with a

reduction in the number of yearlings produced per

female (Rode et al. 2007).

If bears spend more time on land during the open

water period, there is potential for increased disease

transmission (Kirk et al. 2010; Prop et al. 2015; Wiig

Polar Bear Conservation Management Plan 67

Appendix A—Background

et al. 2015), particularly where bears form aggrega-

tions at sites where the remains of subsistence

harvested whales are deposited (e.g., Barter Island

and Cross Island, Alaska). Such aggregations are

also more susceptible to the impacts from potential

oil spills (BOEM 2014).

Increased use of onshore habitat by polar bears

has also led to higher incidences of human-polar

bear conﬂict (Dyck 2006, Towns et al. 2009). In two

studies of polar bears killed by humans in northern

Canada, researchers found that the majority of

polar bears killed in defense-of-life occurred during

the open water season (Stenhouse et al. 1988, Dyck

2006). Thus, as more bears come on shore during

summer, and spend longer periods of time on land,

there is an increased risk of human-polar bear

conﬂict; resulting in more defense-of-life kills and

disruption to industrial, recreational, and subsis-

tence activities.

Seasonal polar bear distribution changes, the nega-

tive effect of reduced access to primary prey, and

prolonged use of terrestrial habitat are all concerns

for polar bears. Although polar bears have been

observed using terrestrial foods such as blueberries

(Vaccinium sp.), snow geese (Anser caerulescens),

and reindeer (Rangifer tarandus), these alternate

foods cannot replace the energy-dense diet polar

bears obtain from marine mammals (e.g., Derocher

et al. 2004, p. 169, Rode et al. 2010b, Smith et al.

2010). Polar bears are not known to regularly hunt

musk oxen (Ovibos moschatus) or snow geese

(Lunn and Stirling 1985, p. 2,295). Thus, greater

use of terrestrial habitats will not offset energy

losses resulting from decreased seal consumption.

Nutritional stress is a likely result. This conclusion

is well-supported by evidence from Western Hudson

Bay, as previously cited.

A.4. Impacts to prey species

Polar bear subpopulations are known to ﬂuctuate

with prey abundance (Stirling and Lunn 1997).

Regional declines in ringed and bearded seal

numbers and productivity have resulted in marked

declines in certain polar bear subpopulations (Stir-

ling and Øritsland 1995; Stirling 2002). Ringed seal

populations are known to exhibit natural ﬂuctua-

tions, but there is concern that longer-term popula-

tion declines associated with sea ice decline might be

overlaid with natural ﬂuctuations (Chambellant et al.

2012). Indeed, ringed seal population dynamics are

a complex mix of biotic and abiotic factors (Pilfold et

al. 2015), making it difﬁcult to understand the direct

inﬂuence of sea ice loss on demography.

Accurate population estimates and trends for these

seal species are unavailable. In 2012, the National

Marine Fisheries Service (NMFS) listed two

prey species of polar bears, the Arctic subspecies

of ringed seal (Phoca hispida hispida) and the

Beringia DPS of bearded seal (Erignathus barbatus

nauticus), as threatened species under the Act (77

FR 76706; 77 FR 76740) due to climate change.

Following successful legal challenges to both

listings in the District Court, the 9

Circuit Court of

Appeals upheld the agency’s listing determination

for the Beringia Distinct Population Segment of

bearded seal on October 24, 2016; NMFS appeal of

the Arctic ringed seal decision (March 11, 2016) is

still pending.

Diminishing ice and snow cover are the greatest

challenges to the persistence of ringed seals.

Within the century, snow cover is projected to be

inadequate for the formation and occupation of

subnivean birth lairs over most of the species’ range

(Kelly et al. 2010, Iacozza and Fergusson 2014). The

thickness of the snow layer surrounding birth lairs is

crucial for thermoregulation and hence, the survival

of nursing pups when air temperatures are below

freezing (Stirling and Smith 2004). Pups in lairs with

thin snow roofs are also more vulnerable to preda-

tion than pups in lairs with thick roofs (Hammill

and Smith 1991, Ferguson et al. 2005). When lack of

snow cover has forced birthing to occur in the open,

nearly 100% of pups died from predation (Smith

and Lydersen 1991, Smith et al. 1991). Additionally,

in some populations, ringed seals are thought to be

increasing their foraging efforts due to changing

environmental conditions with the potential to lead

to negative population-level consequences (Hamilton

et al. 2015).

Rain-on-snow events during the late winter are

increasing and can damage or eliminate snow-

covered pupping lairs (ACIA 2005). The pups are

then exposed to the elements and risk hypothermia.

Damaged lairs or exposed pups are relatively

easy prey for polar bears and arctic foxes (Alopex

lagopus) (Stirling and Smith 2004). Stirling and

Smith (2004) postulated that should early season

rain become regular and widespread in the future,

mortality of ringed seal pups will increase, especially

in more southerly parts of their range.

Pupping habitat on landfast ice (McLaren 1958;

Burns 1970) and drifting pack ice (Wiig et al. 1999;

Lydersen et al. 2004) can be affected by earlier

warming and break-up in the spring, which shortens

the length of time pups have to grow and mature

(Kelly 2001; Smith and Harwood 2001). In addition,

high ﬁdelity of ringed seals to birthing sites makes

them more susceptible to localized impacts from

birth lair snow degradation, harvest, or human

activities (Kelly et al. 2006).

Changes in snow and ice conditions can also affect

polar bear prey other than ringed seals (Born

2005), and will likely result in a net reduction in the

abundance of species such as ribbon seals (Phoca

68 Polar Bear Conservation Management Plan

Appendix A—Background

fasciata) and bearded seals (MacIntyre et al. 2015).

As a result, some polar bear subpopulations likely

will not be able to compensate for the reduced

availability of ringed seals by increasing their taking

of other species (Derocher et al. 2004). Alternatively,

walruses at terrestrial haulouts may become more

available to polar bears as the bears’ use of land

increases, as sea ice extent and duration continues to

decline (Kochnev 2002; Rode et al. 2015b).

A.5. Inadequate conditions for successful denning

Climate change could negatively inﬂuence denning

(Derocher et al. 2004). Insufﬁcient snow would

prevent den construction or result in use of poor

sites where the roof could collapse (Derocher et al.

2004). Changes in the amount and timing of snowfall

could also impact the thermal properties of dens

(Derocher et al. 2004). Since polar bear cubs are

born helpless and need to nurse for three months

before emerging from the den, major changes in the

thermal properties of dens could negatively impact

cub survival (Derocher et al. 2004). Unusual rain

events are projected to increase throughout the

Arctic in winter (Liston and Hiemstra 2011), and

increased rain in late winter and early spring could

cause den collapse (Stirling and Smith 2004). The

proportion of bears denning on ice has decreased for

some subpopulations (Atwood et al. 2016) and not

others, but the consequences of these shifts to cub

survival are unknown.

A.6. Loss of access to denning areas

While polar bears can successfully den on land and

sea ice (Amstrup and Gardner 1994; Fishbach et

al. 2007), for most subpopulations, maternity dens

are located on land (Derocher et al. 2004). Recent

information indicates that some subpopulations,

such as the SB, continue to disproportionately den

on land (Rode et al. 2015a). Female polar bears

can repeatedly return to speciﬁc denning areas on

land (Harrington 1968; Ramsay and Stirling 1990;

Amstrup and Gardner 1994). For bears to access

preferred denning areas on land, pack ice must

drift close enough or must freeze sufﬁciently early

to allow pregnant females to walk or swim to the

area by late October or early November (Derocher

et al. 2004). As distance increases between the pack

ice edge and coastal denning areas, it will become

increasingly difﬁcult for females to access preferred

denning locations unless they are already on or

near land. Distance to the ice edge is one factor

thought to limit denning in western Alaska in the CS

subpopulation (Rode et al. 2015a). Increased travel

distances could negatively affect denning success

and ultimately population size of polar bears (Aars

et al. 2006).

Under most climate change scenarios, the distance

between the edge of the pack ice and land will

increase during summer. Derocher et al. (2004)

predicted that under future climate change

scenarios, pregnant female polar bears will not be

able to reach many of the most important denning

areas in the north coast of the central Beaufort Sea.

Bergen et al. (2007) found that between 1979 and

2006, the minimum distance polar bears traveled to

denning habitats in northeast Alaska increased at an

average linear rate of 6–8 km (3.7–5.0 mi) per year

and almost doubled after 1992. They projected that

travel distances would increase threefold by 2060

(Bergen et al. 2007).

A.7. Loss of mating platform

Moore and Huntington (2008) classify the polar bear

as an “ice-obligate” species because the bears rely

on sea ice as a platform for breeding as well as rest-

ing and hunting. While loss of sea ice may impact

mating success due to a reduction in the ability to

ﬁnd females in estrous (Molnár et al. 2011; Owen et

al. 2015), polar bear habitat projections indicate a

high likelihood of sea ice habitat in spring through at

least mid-century (Durner et al. 2009, Castro de la

Guardia et al. 2013, Hamilton et al. 2014), indicating

that there will likely be suitable ice to serve as a

mating platform into the foreseeable future.

B. Overutilization

Overutilization in the form of human-caused

removals of bears was not found to be a threat to

the population throughout all or a signiﬁcant portion

of its range (USFWS 2008). However, increased

mortality from human-bear encounters or other

forms of mortality may become a more signiﬁcant

threat in the future, particularly for subpopulations

experiencing nutritional stress or declining numbers

as a consequence of habitat change.

Subsistence harvest, management harvest (defense

of life, mercy killings, and removal of problem

bears), and sport harvest (Canada only, using

a proportion of subsistence-allocated tags) are

currently types of human-caused removals that are

allowed throughout all or parts of the polar bear’s

range. Subsistence harvest accounts for the majority

of human-caused removals (Obbard et al. 2010) and

is important to indigenous people in many parts of

the Arctic for nutritional and cultural purposes, and

in some regions provides economic revenue from the

sale of polar bear parts or handicrafts.

A review of new information since 2008 indicates

that overutilization still does not threaten the

species throughout all or a signiﬁcant portion of

its range. This ﬁnding is consistent with reviews of

circumpolar management of polar bears developed

by the IUCN PBSG (Obbard et al. 2010), TRAF-

FIC North America and World Wildlife Fund

Canada (Shadbolt et al. 2012), the Polar Bear

Range States (PBRS 2015), the Animals Committee

Polar Bear Conservation Management Plan 69

Appendix A—Background

of the Convention on the International Trade of

Endangered Species of Fauna and Flora (CITES)

2015 Review of Signiﬁcant Trade (CITES 2015),

and the IUCN Red List Authority (Wiig et al. 2015).

Atwood et al. (2015) concluded that sea-ice loss

due to anthropogenic climate change was the most

important factor in forecasts of the future status of

polar bears worldwide, while in situ human activi-

ties (including human-caused removals) exerted

considerably less inﬂuence on population outcomes.

Harvest management is necessary to ensure that

human-caused removals do not reduce abundance to

unacceptable levels or reduce the viability of popula-

tions (Regehr et al. 2015).

Since 2008, concerns persist about subsistence

harvest levels for several subpopulations, particu-

larly those with poor or outdated population data

(Obbard et al. 2010; Vongraven et al. 2012). The

three polar bear Range States that allow legal

harvest —Canada, Greenland, and the U.S.—have

made progress on the management systems and

scientiﬁc information used to ensure that harvest

does not threaten the species. On a circumpolar

level, a primary concern is the potential for future

overutilization due to interactions between human-

caused removals and negative effects of climate

change. For example, if habitat loss leads to an

increased number of nutritionally-stressed polar

bears on land, human-bear conﬂicts, and resulting

human-caused removals, are expected to increase

(PBRS 2015). Harvest management methods that

consider the current and future potential effects

of habitat loss, the quality of data used to inform

management decisions, and the possibility of popula-

tion thresholds below which increasing conservation

efforts would be made to reduce human-caused

disturbance and removals, are all important

considerations to long-term management of harvest

for populations affected by climate change (Regehr

et al. 2015).

B.1. Management systems and agreements

Human-caused removals are managed in accordance

with numerous laws, legislation and regulations

among and within the ﬁve range state countries

described in “Current Conservation Measures

and Management Efforts” towards the end of this

Appendix. Reviews of international and national

management of human-caused removals of polar

bears are available in Schliebe et al. (2006), USFWS

(2008), Obbard et al. (2010), Shadbolt et al. (2012),

and Polar Bear Range States (2015).

B.2. Subsistence harvest and sport harvest

The U.S., Canada, and Greenland are currently the

only Range States that allow for the subsistence

harvest of polar bears by indigenous people. Polar

bear harvest management regimes vary within

these countries (USFWS 2008; Obbard et al. 2010;

Shadbolt et al. 2012). Polar bear harvest remains

an important nutritional, cultural, and economic

resource for indigenous people in many parts of the

Arctic (e.g., Schliebe et al. 2006; Born et al. 2011;

Voorhees et al. 2014). Canada is the only country

that allows sport hunting, in Nunavut and the

Northwest Territories, through guided hunts that

use a portion of the tags allocated for subsistence

harvest under existing management agreements.

All forms of human-caused removals are generally

included in harvest statistics (noting that some

types of removals, such as subsistence harvest

and defense-of-life kills, are interrelated such that

delineation is difﬁcult). The statistics in this section

reﬂect all reported human-caused removals unless

otherwise noted.

Shadbolt et al. (2012) reported that on average

735 polar bears were killed globally per year from

2006–07 to 2010–11 (winter years), which was three

to four percent of their estimated global population

of 20,000 to 25,000 polar bears (noting that Wiig

et al. [2015] suggested a global population size of

26,000 polar bears [95% CI = 22,000–31,000]). For

polar bears, removing 4.5% of a population annually,

has historically been considered sustainable in the

sense of not causing populations to decline below

the size at which they produce maximum sustain-

able yield (Taylor et al. 1987). Regehr et al. (2015)

corroborated that a 4.5% removal rate is generally

reasonable although some subpopulations may

support higher rates under favorable environmental

conditions, and under some circumstances lower

rates may be necessary to avoid accelerating

population declines caused by habitat loss due to

climate change. Shadbolt et al. (2012) indicated that

Canada harvested the most bears of any Range

State during this period, with an average of 554

bears per year. Greenland removed an average of

136 bears per year, the U.S. removed an average of

45 bears per year, and Norway removed an average

of one bear per year. Information of bears removed

in Russia was not available for their analysis,

although a new survey of communities in Chukotka

provides updated information of the current and

historic number of polar bears removed in that

region (Kochnev and Zdor 2015; see B.3. Poaching

[illegal hunting]).

The mean level of human-caused removal by

subpopulation was reported for the period

2005–2009 by Obbard et al. (2010), and updated

by the IUCN Polar Bear Specialist Group in 2015

(updated versions periodically available at: http://

pbsg.npolar.no/en/status/status-table.html). Recent

harvest levels have been thought to be sustainable

in most subpopulations (Obbard et al. 2010),

although concerns exist for some subpopulations

due to poor or outdated scientiﬁc data, poor or

incomplete reporting of human-caused removals,

70 Polar Bear Conservation Management Plan

Appendix A—Background

or harvest rates that appear excessive in relation

to the best-available estimates of subpopulation

size. The 2015 PBSG Status Table categorized

knowledge on the current trend of 9 subpopulations

as “data deﬁcient.” Vongraven et al. (2012) indicated

that polar bear harvest is closely monitored in

most regions where it occurs, but noted several

subpopulations for which improvements to baseline

harvest data and sampling are needed. Vongraven et

al. (2012) also indicated that, in practice, subsistence

harvest levels are based on factors including scien-

tiﬁc assessments of status, traditional knowledge

information, as well as the level of local interests in

harvesting polar bears for nutritional, cultural, and

economic purposes. The results of Vongraven et al.

(2012) suggest that polar bear subpopulations may

respond to various levels of harvest pressure differ-

ently depending on multiple factors, and the authors

suggest that ﬂexible harvest systems that can adapt

to changing conditions may be necessary to mitigate

and minimize the relative threat legal harvest poses

to polar bear subpopulations.

Regehr et al. (2015) provided a modeling and

management framework for harvesting wildlife

affected by climate change, applied speciﬁcally to

polar bears. That framework uses state-dependent

(i.e., dependent on current condition) management

to identify harvest levels that consider the effects

of changes in environmental carrying capacity (e.g.,

due to sea-ice loss), changes in intrinsic growth rate,

the sex and age of removed animals, the quality of

population data, timing of management decisions,

risk tolerance, and other factors. The authors

evaluate the ability of the harvest management

strategy relative to its ability to achieve two objec-

tives: (i) maintain a population above its maximum

net productivity level relative to a potentially

changing carrying capacity, and (ii) minimize the

effect of harvest on population persistence. Regehr

et al. (2015) demonstrated that harvest adhering to

this framework is unlikely to accelerate population

declines resulting from habitat loss due to climate

change, recognizing that both the harvest level (i.e.,

number of bears removed annually) and harvest rate

(i.e., percent of the population removed annually)

may decline for populations negatively affected by

climate change.

For the SB subpopulation, subsistence harvest

is regulated through an agreement between the

Inuvialuit of Canada and the Inupiat of Alaska (I-I

Agreement; Brower et al. 2002). For the most recent

10-year period 2006–2015, an average of 19 bears

per year were removed from the U.S. portion of

the SB subpopulation (Figure 3). The average sex

composition of removals during this period was 27%

female, 50% male, and 22% unknown.

The U.S. harvest management system for the CS

subpopulation is described in section B.1. Manage-

ment systems and agreements. For the most recent

10-year period 2006–2015, an average of 30 bears

per year (Figure 4) were removed from the U.S.

portion of the CS subpopulation, calculated relative

to the boundary near Icy Cape, Alaska, as recog-

nized by the PBSG (Obbard et al. 2010). The average

sex composition of removals during this period was

29% female, 57% male, and 14% unknown.

B.3. Poaching (illegal hunting)

Given the remoteness of human habitation

throughout polar bear range, poaching is hard to

record and quantify. During the 2008 review, the

Service found limited evidence to suggest that

poaching is a concern in the subpopulations within

the Range States of Canada, Norway, Greenland,

and the U.S. However, poaching may be an issue

for the subpopulations within Russia. The level of

poaching is unknown in the Kara Sea and Laptev

Sea subpopulations (Vongraven et al. 2012) even

though polar bear hunting has been prohibited in

Russia since 1956. Poaching appeared to increase

in northeast Russia (Chukotka) after the collapse

of the Soviet Union affecting the CS subpopulation.

The level of illegal killing was estimated to be high

enough to be unsustainable and to pose a serious

threat to the CS subpopulation in the 1990s (Obbard

et al. 2010). Kochnev (2004) suggested that illegal

hunting in eastern Russia may have been as high as

100 to 200 bears between 1999 and 2003.

Kochnev and Zdor (2015) suggest that illegal hunt-

ing of polar bears in the CS subpopulation removed

approximately 32 bears per year recently, based on

community interviews conducted between 2010 and

2011. This represents a likely decline from the esti-

mated 209 bears killed annually from 1994 to 2003.

Environment Canada reports that illegal hunting in

Canada is a rare event (Environment Canada 2010).

There is little documentation of illegal hunting in

Greenland although two men were charged with use

of illegal equipment in 2011 (Shadbolt et al. 2012).

No documented cases of illegal hunting exist for

Norway (Svalbard). In the U.S., from 2008 to 2015,

only one known bear was illegally taken from the CS

subpopulation in 2013. Wiig et al. (2015) reported

that range-wide illegal hunting of polar bears is not

thought to be a major concern.

B.4. Defense-of-life removals

Human-bear interactions and defense-of-life kills

may increase under projected climate change

scenarios where more bears are on land and in

contact with humans (Derocher et al. 2004). Polar

bears are inquisitive animals and often investigate

novel odors or sights. This trait can lead to polar

bears being killed when they investigate human

activities (Herrero and Herrero 1997). Since the

late 1990s, the timing of freeze-up in the autumn has

occurred later and later, resulting in an increased

Polar Bear Conservation Management Plan 71

Appendix A—Background

amount of time polar bears spend on land in some

areas (Rode et al. 2015b). This can increase the

probability of human-bear interactions. With projec-

tions indicating that the Arctic Ocean may be largely

ice free in the summer in the next few decades

(Overland and Wang 2013), human-polar bear

conﬂicts are expected to increase as bears are forced

on shore and closer to people (Dyck 2006; Regehr

et al. 2007a; Towns et al. 2009). Understanding and

addressing human-bear conﬂicts will ultimately help

reduce the necessity to lethally remove a polar bear

in defense of a human life.

A primary management goal of the Range States

is to ensure the safe coexistence of polar bears and

humans in the face of accelerating climate change.

In order to monitor human-polar bear interactions

throughout the Arctic, the Range States initiated

development of a database to track and analyze

human-polar bear conﬂicts. The Polar Bear-Human

Information Management System (PBHIMS)

database will document, quantify, and evaluate

human-bear interactions and other information

relevant to bear management (PBRS 2015). This

information will then be analyzed and the ﬁndings

used to develop improved management strategies

to reduce human-bear conﬂicts and the number of

bears killed.

Since 2008, human-polar bear conﬂict reduction has

become an important issue for many circumpolar

communities. In recent years, these efforts have

increased and have incorporated multiple groups.

Non-government organizations (NGOs) have

been working with government agencies and local

communities throughout the Arctic to provide

information and training, remove attractants from

villages, provide bear-proof storage containers for

food, provide electric fencing, and fund polar bear

patrols (Voorhees and Sparks 2012; York et al. 2014).

These initiatives strive to minimize human-bear

conﬂicts and create safe communities; however,

much work remains. Reducing human-bear conﬂicts

through attractants management, such as managing

human food and garbage or managing natural

attractants (i.e., whale carcass sites) in or near

human settlements continues to be an important and

challenging issue for Arctic communities and wildlife

managers (Koopmans 2011; Aerts 2012; ANC 2013;

York et al. 2014).

Polar bear patrols in coastal communities are

another effective technique to reduce human-bear

conﬂicts through deterrence and education. These

structured programs enable trained, local residents

to deter polar bears from entering communities

using a variety of non-lethal techniques (ANC 2013).

While deterrence may not be effective for every

bear, it does provide a non-lethal option for keeping

bears out of communities in the majority of cases.

Established polar bear patrols now occur in the

U.S., Canada, Greenland, and Russia.

Since the listing in 2008, in Alaska, two defense-of-

life removals from the SB subpopulation by non-

Alaska Natives occurred with humans engaged in

recreational activities. The ﬁrst incident occurred in

August 2014 at Bullen Point and the second occurred

a week later in the Arctic National Wildlife Refuge.

Figure 3. Polar bear harvest in the U.S. portion of the

Southern Beaufort Sea subpopulation 2006–2015.

Unknown

Male

Female

Year

Polar Bears

Harvest in the U.S. portion of the Southern Beaufort Sea region

Figure 4. Polar bear harvest in the U.S. portion of the

Chukchi Sea subpopulation 2006–2015.

Unknown

Male

Female

Year

Polar Bears

Harvest in the U.S. portion of the Chukchi Sea region

72 Polar Bear Conservation Management Plan

Appendix A—Background

B.5. Other removals

Other forms of removal include take associated

with accidental mortality during scientiﬁc research,

during industrial activities and placement of

orphaned cubs into public display facilities. These

sources of mortality are generally included in

estimates of total removals provided previously. In

2008, these levels of take were sufﬁciently low that

the Service determined they were insigniﬁcant and

had no effect on population status. New information

summarized below indicates this is still an accurate

assessment.

Research. Research activities may cause short-term

effects to individual polar bears targeted in survey

and capture efforts (Thiemann et al. 2013) and may

incidentally disturb those nearby. In rare cases,

research efforts may lead to injury or death of polar

bears. Between 1967 and 2012, there were around

4401 capture events of polar bears in Alaska with

at least 19, and perhaps as many as 27, deaths (a

capture mortality rate ranging from 0.4 – 0.6% since

1967). In 2001 the USGS began an intensive capture/

mark/recapture project in the southern Beaufort

Sea that is ongoing and mortality has been low (3

research related mortalities resulting from 1260

captures, or .24%). Capture efforts in the southern

Beaufort Sea, however, have not resulted in any

long-term effects on body condition, reproduction,

or cub survival (Rode et al. 2014a)

Orphaned cubs. In the U.S., two orphaned cubs-

of-the year have been removed from their natural

environment since 2008. In 2011, one orphaned

female cub from the SB subpopulation was recov-

ered in an industrial area after apparently being

separated from its mother. It was subsequently sent

to a public display facility. In 2013, one orphaned

male cub of the year that was recovered from the CS

subpopulation as a stranded animal after its mother

was harvested. It was subsequently sent to a public

display facility for long term care and maintenance.

No other recent information on orphaned cubs has

been documented from other countries.

Industrial activities. Climate change is expected

to increase accessibility to natural resources in the

Arctic, effectively increasing industrial activities

and its support infrastructure in the circumpolar

regions. Industries, such as mineral extraction, ship-

ping, and petroleum exploration and development,

are all expected to increase in the future.

Three polar bear removals have occurred from the

SB subpopulation since the listing as a result of

industry activities, and one removal occurred as a

result of deterrence activities. In 2011, a security

guard for an oil company accidently shot and killed

a female polar bear during a deterrence action. In

2012, one adult female and her two-year old male

cub were found dead on an island near industry

facilities. Their deaths are assumed to be related to

the chemical substances found in and on the bears.

In 2012, an additional lethal removal from the SB

subpopulation occurred during a deterrence action

of a community bear patrol. Since 2008, no other

recorded removals as a result from industrial activi-

ties have been documented. Industrial activities are

further discussed in Section E.1.

C. Disease and predation

In the Final Rule for listing polar bears under the

Act (73 FR 28212), the Service examined the best

available scientiﬁc information on disease and

determined that diseases do not threaten the species

throughout all or any signiﬁcant portion of its range.

A further review of new information since 2008

indicates that disease and predation continue to pose

little threat to the species.

C.1. Disease

Polar bears are not generally susceptible to disease

and parasites (USFWS 2008). The Service noted

in 2008 that the potential for disease outbreaks, an

increased possibility of pathogen exposure from

changing diets, increased susceptibility of polar

bears to existing pathogens, or the occurrence of

new pathogens that have moved northward with

a warming environment all warrant continued

monitoring and may become more signiﬁcant threat

factors in the future for polar bear populations

experiencing nutritional stress or declining numbers

(USFWS 2008).

Fagre et al. (2015) conducted a literature review of

existing papers describing infectious diseases that

have been reported in polar bears. They noted that

in reports where wild polar bears have been exposed

to various bacteria, fungi, parasites and viruses,

limited information on health effects were reported.

They also documented that the majority of diseases

found in captive polar bears do not occur in the

Arctic environment and thus may have limited value

for understanding the importance of these diseases

in wild bear populations.

C.2. Emergence of new pathogens in polar bears

Whether polar bears are more susceptible to new

pathogens due to their lack of previous exposure to

diseases and parasites is unknown. As the effects of

climate change become more prevalent, there are

concerns with the expansion of existing pathogens

from southern latitudes moving into the polar

bears’ range (Weber et al. 2013). New pathogens

may expand their range northward from more

southerly areas under projected climate change

scenarios (Harvell et al. 2002). Further, the potential

for pathogens crossing human-animal boundaries

Polar Bear Conservation Management Plan 73

Appendix A—Background

(e.g. giardia), and new threats from existing

pathogens that may be able to establish in immuno-

compromised/stressed individuals is also a concern.

Many different pathogens and viruses have been

found in seal species that are polar bear prey, so the

potential exists for transmission of these diseases to

polar bears.

Patyk et al. (2015) suggested that due to the

predicted effects of climatic warming and the

synergistic effects of pollutants on polar bears’

resistance to disease and parasites, establishing

good baseline data for the most common diseases in

different populations of polar bears and by tracking

temporal trends in prevalence for each disease could

help future research and monitoring.

C.3 Intraspeciﬁc competition

While cannibalism has been documented among

polar bears (Derocher and Wiig 1999; Amstrup et

al. 2006; Stirling and Ross 2011) and infanticide by

male polar bears have been documented (Taylor et

al. 1985; Derocher and Wiig 1999; Stone and Dero-

cher 2007), there is no indication that these stressors

have resulted in population level effects.

C. 4. Interspeciﬁc competition

One form of interspeciﬁc competition is cross-

breeding, or hybridization. The ranges of polar

bears and grizzly bears overlap only in portions of

northern Canada, Chukotka (Russia), and northern

Alaska. The ﬁrst documented case of cross-breeding

in the wild was a ﬁrst generation male hybrid

harvested on Banks Island, Canada in 2006. This

hybrid was the result of the cross-breeding between

a female polar bear and male grizzly bear (Paetkau,

pers. comm. May 2006). Since then, two additional

hybrids have been harvested on Victoria Island and

multiple sightings have been conﬁrmed in Canada,

one of which is considered a “second generation”

hybrid, the result of a female grizzly-polar hybrid

mating with a male grizzly bear (Species at Risk

Committee 2012). Further, in April 2012, an adult

female polar bear was harvested with two older ﬁrst

generation hybrid cubs (Species at Risk Committee

2012). Cross-breeding in the wild is thought to be

rare, but cross-breeding may pose concerns for

subpopulations and species viability in the future

should the rate of occurrence increase. Based on the

harvest and sighting locations, polar bears affected

by cross-breeding with grizzly bears presumably

are part of the NB and Viscount Melville subpopula-

tions.

Along Alaska’s northern coast, polar bears compete

with brown bears for food sources. Results from a

study conducted in 2005–2007 (Miller et al. 2015)

indicate that brown bears are socially dominant

and frequently displace polar bears from an annual

bowhead whale carcass food source. The physiologi-

cal effects of these interactions on individual polar

bears are not fully determined.

D. Inadequacy of existing regulatory mecha-

nisms

In the Final Rule (73 FR 28212), the Service

reviewed existing regulatory mechanisms and

determined that potential threats to polar bears

from direct take, disturbance by humans, and

incidental or harassment take are, for the most

part, adequately addressed by existing regulatory

mechanisms. However, there are no known regula-

tory mechanisms in place at the national or interna-

tional level that directly and effectively address the

primary threat to polar bears—the range-wide loss

of sea ice habitat within the foreseeable future (73

FR 28293, May 15, 2008).

As noted above, since 2008, there are no known

mechanisms that effectively regulation greenhouse

gas emissions, which are contributing to global

climate change and associated modiﬁcations to polar

bear habitat. However, governments and concerned

organizations are trying to address climate change

impacts on a global level. Recently, at the Paris

Climate Conference held in December 2015, 195

countries adopted the ﬁrst universal, global climate

agreement. This agreement presents a global action

plan that is meant to limit global warming to below

2°C by the end of the century (EC 2016; http://

ec.europa.eu/clima/policies/international/negotia-

tions/paris/index_en.htm). On April 22, 2016, all ﬁve

polar bear range state countries signed the Paris

Agreement.

E. Other natural or manmade factors affecting

the polar bear’s continued existence

In the Final Rule for listing polar bears under the

Act (73 FR 28212), the Service examined the best

available scientiﬁc information on other natural or

manmade factors affecting polar bears’ continued

existence, such as 1) contaminants; 2) shipping and

transport; and 3) ecotourism, and determined that

they did not threaten the species throughout all

or any signiﬁcant portion of its range. A further

review of new information since 2008 indicates that

these factors still do not threaten the polar bear

throughout its range, but have the potential to pose

a more signiﬁcant risk in the future.

E.1. Contaminants

Although loss of sea ice is the greatest threat to

polar bears, contaminants can exacerbate the

effects of this and other threats. Understanding

the potential effects of contaminants on polar bears

in the Arctic is confounded by the wide range of

74 Polar Bear Conservation Management Plan

Appendix A—Background

contaminants present, each with different chemical

properties and biological effects, and their differing

geographic, temporal, and ecological exposure

regimes. In the Final Rule, the Service identiﬁed

three main groups of contaminants in the Arctic that

present the greatest potential threats to polar bears

and other marine mammals: persistent organic

pollutants (POPs), heavy metals, and petroleum

hydrocarbons. The Service concluded that contami-

nant concentrations were not thought to have

population level effects on most polar bear popula-

tions, but also noted that contaminants may become

a more signiﬁcant threat in the future, especially

for polar bear subpopulations experiencing declines

related to nutritional stress brought on by sea ice

loss and environmental changes.

E.1.a. Persistent organic pollutants (POPs)

Persistent organic pollutants are organic chemicals

resistant to biodegradation that can remain in the

environment for a long period of time. They are of

particular concern to apex species such as polar

bears that have low reproductive rates and high

lipid levels because POPs tend to bioaccumulate

and biomagnify in fatty tissues. The presence and

persistence of these contaminants is dependent

on factors such as transport routes, distance from

source, and quantity and chemical composition of

their releases.

In the Final Rule, the Service noted that the

Barents Sea (BS), East Greenland (EG), Kara Sea

(KS), and some Canadian polar bear subpopulations

have the highest overall contaminant concentrations.

While the levels of some contaminants, such as

polychlorinated biphenyls (PCBs), generally seem to

be decreasing in polar bears, others, such as hexa-

chlorocyclohexanes (HCHs), were relatively high,

and newer compounds, such as, polybrominated

diphenyl ethers (PBDEs) and perﬂouro-octane

sulfonates (PFOS), posed a potential future risk to

polar bears. The effects of these contaminants at

the population level were considered to be largely

unknown.

In Alaska, contaminant levels in polar bear

subpopulations at the time of listing were considered

relatively low compared to other subpopulations.

A study by Bentzen et al. (2008) showed that the

variation in contaminant levels in polar bears may

be due to variation in diet and biomagniﬁcation of

organochlorines in relation to sex, age, and trophic

position. Alaskan subpopulations continue to have

some of the lowest concentration of PCBs, chlo-

rinated pesticides, and ﬂame retardants of all the

polar bear subpopulations (McKinney et al. 2011).

E.1.b. Metals

In the Final Rule, the Service noted that mercury is

the element of greatest concern to polar bears, and

that the highest concentrations have been found in

the Viscount Melville Sound and SB subpopulations.

The Service noted that, although mercury found

in marine mammals often exceed levels that have

caused effects in terrestrial mammals; most marine

mammals appear to have evolved mechanisms that

allow tolerance of higher concentrations of mercury

(AMAP 2005).

While some contaminants have decreased in overall

levels, indicating that international regulations can

be effective in reducing contaminants, slow declines

of some legacy pollutants like PCBs, coupled with

exposure to “new” chemicals, continue to be a

concern to polar bear health (McKinney et al. 2009),

especially in Greenland and Norway. Since mercury

is known to impact the neurological and reproduc-

tive health in other mammals, and is expected to

continue to increase in polar bear populations over

time, mercury should continue to be an important

focus of future polar bear monitoring efforts and

toxicological studies. Although population-level

effects are still widely un-documented for most

polar bear subpopulations, increasing exposure

to contaminants may become a more signiﬁcant

threat in the future, especially for declining polar

bear subpopulations and/or bears experiencing

nutritional stress. Therefore, contaminants should

continue to be closely monitored.

E.1.c. Petroleum hydrocarbons

Petroleum hydrocarbons can be introduced into

polar bear habitat from industrial development

and shipping. As noted in the Final Rule, polar

bears overlap with both active and planned oil and

gas operations throughout their range. Impacts

on polar bears from industrial activities, such as

oil and gas development, may include: disturbance

from increasing human-bear interactions, resulting

in direct displacement of polar bears, preclusion of

polar bear use of preferred habitat (most notably,

denning habitat); and/or displacement of primary

prey. Also, increases in circumpolar Arctic oil and

gas development, coupled with increases in shipping

due to the lengthening open water season, increase

the potential for an oil spill to impact polar bears

and their habitat.

Industrial development. Oil and gas activities have

occurred in every polar bear Range State, either in

the onshore or offshore environment. At the time

of listing, the greatest level of oil and gas activity

occurring within polar bear habitat was in the

United States (Alaska). The Service determined

that direct impacts on polar bears from oil and gas

exploration, development, and production activities

had been minimal and did not threaten the species

Polar Bear Conservation Management Plan 75

Appendix A—Background

overall. This conclusion was based primarily on:

1) the relatively limited and localized nature of

the development activities; 2) existing mitigation

measures that were in place; and 3) the availability

of suitable alternative habitat for polar bears. The

Service also noted that data on direct quantiﬁable

impacts to polar bear habitat from oil and gas

activities was lacking.

Petroleum development is cyclic in nature and

susceptible to market demands. Currently, oil

and gas exploration, development and production

throughout the Arctic has declined since the time of

the listing.

In 2006 oil exploration interests expanded into the

Chukchi Sea within range of the CS polar bear

subpopulation. Since listing, lease sales have been

held in both the Beaufort and Chukchi seas, and

high value polar bear habitat was identiﬁed in

the Chukchi Sea lease area (Wilson et al. 2014).

However, since 2014, market mechanisms, such as

a decline in the value of oil, have led to a decline

in pursuing petroleum development at this time in

both the Beaufort and Chukchi seas. This has also

resulted in cancellation of future lease sales (USDOI

2015) and the relinquishment of lease holding by

companies back to the U.S. government.

Ongoing oil and gas production continues in central

Beaufort Sea, within range of the SB subpopulation.

Two new offshore developments have begun produc-

ing oil since the time of listing. Additionally, another

offshore development initiated the permit process

to develop an oil ﬁeld in the Beaufort Sea (BOEM

2015).

All oil and gas activities continue to be evaluated and

regulated in the United States. Potential effects on

polar bears are mitigated through: 1) development

of activity-speciﬁc human-bear interaction plans

(to avoid disturbance), 2) safety and deterrence

training for industry staff, 3) bear monitoring and

reporting requirements, and 4) implementation of

project-speciﬁc protection measures (e.g., 1 mile

buffers around den sites). In 2015, the Depart-

ment of the Interior released additional proposed

regulations for future, offshore exploratory drilling

activities in the U.S. Arctic (USDOI 2015). These

regulations are intended to improve operational

standards from mobilization to transport, drilling,

and emergency response in a manner that the entire

exploration operation can be conducted in a safe

manner. Additionally, a review of potential impacts,

including cumulative effects, is conducted every

ﬁve years through the Service’s Incidental and

Intentional Take Program; the most recent reviews

(in 2016 and 2013 for the Beaufort and Chukchi

seas, respectively) include “ﬁndings of no signiﬁcant

impact” to polar bears.

Oil spills. Oil spills were identiﬁed as a primary

concern for polar bears throughout their range

in the Final Rule. The primary threats to polar

bears from an oil spill are: 1) inability to effectively

thermoregulate when their fur is oiled, 2) ingestion

of oil from grooming or eating contaminated prey, 3)

habitat loss or precluded use of preferred habitat;

and 4) oiling and subsequent reduction of prey.

Spilled oil present in the autumn or spring during

formation or breakup of ice presents a greater risk

than in open water or ice-covered seasons because of

the difﬁculties associated with cleaning oil in mixed,

broken ice, and the presence of bears and other

wildlife in prime feeding areas over the continental

shelf during this period.

At the time of listing, no major oil spills had

occurred in the marine environment within the

range of polar bears and the Service had determined

that the probability of a large scale oil spill occur-

ring in polar bear habitat and affecting the species

range wide was low. The Service also noted that, in

Alaska: 1) past history in the Beaufort and Chukchi

seas has demonstrated that operations can be

conducted safely, and effects on wildlife and the

environment minimized; 2) regulations are in place

that provide for pollution prevention and control, as

well as marine mammal monitoring and avoidance

measures; and 3) plans are reviewed by both leasing

and wildlife agencies prior to any activity so that

protective measures speciﬁc for polar bears can be

put into place with any new activity. However, the

Service also noted that increased circumpolar Arctic

oil and gas development, coupled with increased

shipping, increased the potential for an oil spill, and

if a large spill were to occur, it could have signiﬁcant

impacts to polar bears and their prey, depending

on the size, location, and timing of the spill, and the

number of animals affected.

Since the 2008 listing, the level of information and

number of entities generating information on oil

spill preparedness has been increasing in the Arctic

(Holland-Bartels and Pierce 2011). For example,

at the circumpolar level, the Arctic Council‘s

Protection of the Arctic Marine Environment

(PAME) working group produced the Arctic Marine

Shipping Assessment 2009 Report (AMSA 2009)

which identiﬁed oil spill prevention as the highest

priority in the Arctic for environmental protection.

The PAME working group is functioning to enhance

cooperation in the ﬁeld of oil spill prevention, and

support research and technology that helps prevent

release of oil into Arctic waters (www.pame.is).

Additionally, in 2014, the member nations of the

Arctic Council signed a Cooperative Agreement to

strengthen cooperation, coordination, and mutual

assistance regarding oil pollution preparedness and

response in the Arctic and to protect the marine

environment from oil pollution (www.arcticcouncil.

org/eppr/). These initiatives will help countries be

76 Polar Bear Conservation Management Plan

Appendix A—Background

better prepared for oil spills, thereby beneﬁtting

polar bears if a spill were to occur.

In Alaska, the Oil Spill Risk Analysis process

continues to be used by federal managers to identify

where natural resources might be exposed to oil

under various spill scenarios. For example, as

part of the lease sale process, the Bureau of Land

Management (BLM) and Bureau of Ocean Energy

Management (BOEM) modeled the likelihood of

spills occurring during exploration and development

in both the National Petroleum Reserve-Alaska

(NPR-A) (BLM 2012) and in the Beaufort and

Chukchi Sea planning areas (BOEM 2011, 2014;

respectively). Large (greater than 1,000 bbl) or very

large spills (greater than 120,000 bbl) were consid-

ered unlikely to occur during oil and gas exploration

(BOEM 2014). They also concluded that while a very

large oil spill is a highly unlikely event, if one did

occur it could result in the loss of large numbers of

polar bears and could have a signiﬁcant impact on

the SB and CS polar bear subpopulations.

In terms of response measures, a planning tool

known as the Net Environmental Beneﬁt Analysis

has been developed that can be used as a decision-

making process to identify spill response methods

that are most likely to reduce environmental threats

in the Arctic (Potter et al. 2012). Additionally, new

detection tools, such as, laser ﬂuorosensors and

unmanned aircraft systems, have been tested and

used to detect and track oil in snow and ice, and they

appear to have applications to minimize oil impacts

to polar bears (EPPR 2015).

Further, considerable research has been conducted

on the use of in-situ burning (ISB), dispersants,

and chemical herders as response tools for cleaning

up oil in the ice environment, some with promising

results (Brandvik et al. 2010, Sørstrøm et al 2010,

Potter et al. 2012). Recent technology developments

include: better ﬁre resistant boom, use of herding

agents in conjunction with ISB, improvements to

dispersant formulas, and better equipment and

delivery systems (Potter et al. 2012). Signiﬁcant data

gaps still exist in terms of understanding the toxicity

from chemical herders and dispersant to Arctic

species (Holland-Bartels and Pierce 2011).

Although the risk of a large enough oil spill affect-

ing a signiﬁcant portion of the world-wide polar

bear population remains unlikely, the potential

consequences warrant continued monitoring and

mitigation of industries that have the potential to

spill oil into the Arctic environment. Progress is

continuing at local, national and international levels

on planning, response operations speciﬁc to polar

bears.

E.2 Shipping and transportation

In the Final Rule, the Service noted that a decline

in Arctic sea ice has resulted in an increase in

the navigation season within Arctic waters, and

identiﬁed increased shipping as an emerging issue

for polar bear conservation. Previously ice-covered

sea routes are now opening up in summer, allowing

access for commercial shipping. Increased shipping

along the Northern Sea Route (part of the North-

east Passage that follows Norway and Russia’s coast

down into the Chukchi and Bering seas), and the

Northwest Passage (which follows Canada’s eastern

coast north along Canada and Alaska’s Beaufort

Sea coast) could result in increased fragmentation

of sea ice habitat and disturbance/injury to marine

mammals, increased human-bear encounters, and

the introduction of waste/ litter, and toxic pollutants

into the marine environment (PBRS 2015). A

primary concern associated with increased shipping

is the increased potential for oil spills to occur.

While no population level effects from increased

shipping were identiﬁed at the time of listing, the

IUCN Polar Bear Specialist Group recommended

that the Range States take appropriate measures to

monitor, regulate, and mitigate ship trafﬁc impacts

on polar bear populations and their habitat (Aars et

al. 2006).

Since the listing, increased attention on shipping

as an emerging Arctic issue has occurred at the

circumpolar level. For example, the Arctic Council

completed a comprehensive Arctic marine shipping

assessment report (AMSA 2009) that focused on

ship uses of the Arctic Ocean and their potential

impacts on humans and the Arctic marine environ-

ment (AMSA 2009). The AMSA Report includes a

comprehensive estimate of how many ships (exclud-

ing naval vessels) operated in the Arctic during a

given year, and identiﬁed Arctic natural resource

development and regional trade as the key drivers of

future Arctic marine activity. The release of oil was

identiﬁed as one of the most signiﬁcant environmen-

tal threats related to shipping. The report included

a speciﬁc recommendation for Arctic countries to

address impacts on marine mammals from shipping,

and work with the International Maritime Organiza-

tion (IMO) to develop and implement mitigation

strategies.

Since then, signiﬁcant advancements have been

made to implement the recommendations set forth

in the AMSA Report. For example, several reports

that identify Arctic marine areas of special ecologi-

cal and cultural importance have been published

(Smith et al. 2010), and voluntary guidelines to

reduce underwater noise to avoid adverse impacts

on marine biota have been developed (PAME 2015).

Additionally, vessel routing and speed restrictions

have been recognized as effective measures to

Polar Bear Conservation Management Plan 77

Appendix A—Background

mitigate impacts on marine mammals (Brigham and

Sfraga 2010). In 2015, the IMO adopted the envi-

ronmental provisions of the Polar Code, a signiﬁcant

achievement for addressing marine environmental

protection which includes standardized safety

procedures such as use of designated ship lanes. The

Polar Code is expected to enter into force in Janu-

ary 2017 (IMO 2016). In the U.S., steps are being

taken to establish designated shipping routes in the

Bering Strait and Chukchi Sea (USCG 2014), areas

known for their biological (and cultural) importance

(Huntington et al. 2015).

Potential impacts from shipping on polar bears

continue to warrant attention. At present, ongoing

circumpolar efforts to improve marine safety and

environmental protection are positive steps toward

addressing potential impacts on marine mammal

species, including polar bears.

E.3. Ecotourism

Polar bear viewing and photography are popular

forms of tourism that occur primarily in Churchill,

Canada; Svalbard, Norway; and the north coast of

Alaska (the communities of Kaktovik and Barrow).

In the Final Rule, the Service noted that, while it is

unlikely that properly regulated tourism will have

a negative effect on polar bear subpopulations,

increasing levels of public viewing and photography

in polar bear habitat may lead to increased

human-polar bear interactions. Tourism can also

result in inadvertent displacement of polar bears

from preferred habitats, or alter natural behaviors

(Lentfer 1990; Dyck and Baydack 2004, Eckhardt

2005). If increased human-bear conﬂicts lead to

polar bears being killed in defense of life, this could

also lead to reduced opportunities for subsistence

harvest. Conversely, tourism can have the positive

effect of increasing the worldwide constituency

of people with an interest in polar bears and their

conservation.

Since the listing, the human dimension aspect

and role of stakeholders in polar bear viewing has

increased. It has been noted that wildlife tourism

conservation activities have a greater potential for

success if local people take part in developing and

implementing programs (Lemelin and Dyck 2008).

Increasing polar bear tourism does not appear to

have emerged as a signiﬁcant threat to the world

wide population of polar bears, and may contribute

positively to polar bear conservation. Negative

effects may occur in areas where regulations and

involvement from local stakeholders is lacking.

Cooperative relationships that develop between

managers and community residents will become

increasingly important if tourism to observe polar

bears continues to grow.

Current Conservation Measures and

Management Efforts

Many governmental and non-governmental agen-

cies, institutions, and organizations are involved in

polar bear conservation. These entities provide an

active conservation constituency and are integral

to the conservation/recovery of the species. The

following conservation agreements and plans

have effectively addressed many threats to polar

bears from direct and incidental take by humans.

However, as noted in the “Threats” section, there

are no known regulatory mechanisms in place at

the national or international level that directly and

effectively address the primary threat to polar

bears—the range-wide loss of sea ice habitat within

the foreseeable future.

A. International Conservation Agreements and

Plans

 Agreement on the Conservation of Polar

Bears (1973 Agreement). All ﬁve range

countries are parties to the 1973 Agreement.

The 1973 Agreement requires the Range

States to take appropriate action to protect

the ecosystem of which polar bears are a part,

with special attention to habitat components

such as denning and feeding sites and

migration patterns, and to manage polar bear

subpopulations in accordance with sound

conservation practices based on the best

available scientiﬁc data. The 1973 Agreement

relies on the efforts of each party to implement

conservation programs and does not preclude

a party from establishing additional controls

(Lentfer 1974, p. 1). In 2009, the Range States

agreed to initiate a process that would lead to

a coordinated approach to conservation and

management strategies between the parties.

A Circumpolar Action Plan for the polar bear

(Polar Bear Range States 2015) was developed

to synthesize and coordinate management

and conservation activities among countries,

in conjunction with National Action Plans

developed by individual range states.

 Inupiat—Inuvialuit Agreement for the

Management of Polar Bears of the Southern

Beaufort Sea. In January 1988, the Inuvialuit

of Canada and the Inupiat of Alaska, groups

that both harvest polar bears for cultural and

subsistence purposes, signed a management

agreement for polar bears of the Southern

Beaufort Sea (I-I Agreement) (Brower et

al. 2002). This agreement is based on the

understanding that the two groups harvest

animals from a single population shared

across the international boundary. The I-I

Agreement provides joint responsibility for

78 Polar Bear Conservation Management Plan

Appendix A—Background

conservation and harvest practices (Treseder

and Carpenter 1989; Nageak et al. 1991).

In Canada, recommendations and decisions

from the I-I Commissioners are implemented

through Community Polar Bear Management

Agreements, Inuvialuit Settlement Region

Community Bylaws, and NWT Big Game

Regulations. In the United States, the I-I

Agreement is implemented at the local level.

Adherence to the agreement’s terms in Alaska

is voluntary, and levels of compliance may vary.

 Agreement between the United States of

America and the Russian Federation on

the Conservation and Management of the

Alaska—Chukotka Polar Bear Population

(Bilateral Agreement). In October 16, 2000,

the United States and the Russian Federation

signed a bilateral agreement for the conserva-

tion and management of polar bear subpopula-

tions shared between the two countries.

The Bilateral Agreement expands upon the

progress made through the multilateral

1973 Agreement by implementing a uniﬁed

conservation program for this shared popula-

tion. Beginning in 2007, parties to the treaty

established a joint U.S.-Russia Commission

responsible for making management decisions

concerning polar bears in the Alaska-Chukotka

region. The Commission is composed of a

Native and federal representative from each

country. The Commissioners have appointed a

scientiﬁc working group (SWG) and tasked this

SWG with a number of objectives, with the top

priority being identifying a sustainable harvest

level for the Alaska-Chukotka population.

In response to this initiative, the SWG provided

the Commission with a peer-reviewed report of

their recommendations regarding harvest and

future research needs. At a meeting in June 2010,

the Commission decided to place an upper limit

on harvest from the CS population of 19 female

and 39 male (for a total of 58) polar bears per year

based on the recommendation of the SWG and

subsistence needs. Harvest will be split evenly

between Native peoples of Alaska and Chukotka.

The Service and the Alaska Nanuuq Commission

(ANC) will work in partnership with local commu-

nities to implement the harvest quota.

 Memorandum of Understanding between

Environment Canada and the United States

Department of the Interior Concerning the

Conservation and Management of Shared

Polar Bear Populations. In May 2008, the

Canadian Minister of Environment and

the U.S. Secretary of the Interior signed a

Memorandum of Understanding to facilitate

and enhance coordination, cooperation, and

the development of partnerships between the

Participants, and with other associated and

interested entities, regarding the conservation

and management of polar bears and to

provide a framework for the development

and implementation of mutually agreeable

immediate, interim, and long-term actions

that focus on speciﬁc components of polar bear

conservation.

 The Convention on International Trade

in Endangered Species of Wild Fauna

and Flora (CITES) is a treaty designed

to protect animal and plant species at risk

from international trade. CITES regulates

international wildlife trade by listing species

in one of its three appendices; the level of

monitoring and regulation to which an animal

or plant species is subject depends on the

appendix in which it is listed. Polar bears were

listed in Appendix II of CITES on July 7,

1975. As such, CITES parties must determine,

among other things, that any polar bear,

polar bear part, or product made from polar

bear is legally obtained and that the export

will not be detrimental to the survival of the

species, prior to issuing a permit authorizing

the export of the animal, part, or product. All

ﬁve range states are CITES signatories and

have the required Scientiﬁc and Management

Authorities. CITES is effective in regulating

the international trade in polar bear parts and

products, and provides conservation measures

to minimize that potential threat to the species.

B. Domestic Regulatory Mechanisms

 The Marine Mammal Protection Act

(MMPA) was enacted on October 21, 1972.

All marine mammals, including polar bears,

are protected under the MMPA. The MMPA

prohibits, with certain exceptions, the “take”

of marine mammals in U.S. waters and by U.S.

citizens on the high seas, and the importation

of marine mammals and marine mammal

products into the U.S. (http://www.nmfs.noaa.

gov/pr/laws/mmpa/).

Passage of the MMPA in 1972 established a

moratorium on sport and commercial hunting

of polar bears in Alaska. However, the MMPA

exempts harvest, conducted in a non-wasteful

manner, of polar bears by coastal dwelling Alaska

Natives for subsistence and handicraft purposes.

The MMPA and its implementing regulations

also prohibit the commercial sale of any marine

mammal parts or products except those that

qualify as authentic articles of handicrafts or

clothing created by Alaska Natives.

Section 119 of the MMPA was added to allow the

Secretary to “enter into cooperative agreement

with Alaska Native organizations to conserve

marine mammals and provide co-management

Polar Bear Conservation Management Plan 79

Appendix A—Background

of subsistence use by Alaska Natives.” This also

authorizes grants to be made to Native organiza-

tions in order to carry out agreements made

under the section.

The MMPA Incidental and Intentional Take

Program (IITP) allows for the incidental non-

intentional take of small numbers of marine

mammals during speciﬁc activities. The MMPA

also allows for intentional take by harassment

of marine mammals for deterrence purposes.

The Service administers an IITP that allows

polar bear managers to work cooperatively with

stakeholders (i.e., oil and gas industry, the mining

industry, the military, local communities, and

researchers) working in polar bear habitat to

minimize impacts of their activities on bears. The

IITP has been an integral part of the Service’s

management and conservation program for polar

bears in Alaska since its inception in 1991. The

program’s success depends on its acceptance by

our conservation partners

 The Endangered Species Act was passed to

provide a mechanism to conserve threatened

and endangered plants and animals and their

habitat. Listing implements prohibitions on

the take of the species. Under section 7 of the

ESA, all Federal agencies must ensure that

any actions they authorize, fund, or carry

out are not likely to jeopardize the continued

existence of a listed species, or destroy or

adversely modify its designated critical

habitat. Consultations occur with Federal

action agencies under section 7 of the ESA

to avoid and minimize impacts of proposed

activities on listed species.

 The Alaska National Interest Lands

Conservation Act of 1980 (16 U.S.C. 3101 et

seq.) (ANILCA) created or expanded National

Parks and National Wildlife Refuges (NWRs)

in Alaska, including the expansion of the Arctic

NWR. One of the establishing purposes of the

Arctic NWR is to conserve polar bears. Section

1003 of ANILCA prohibits production of oil

and gas in the Arctic NWR, and no leasing or

other development leading to production of oil

and gas may take place unless authorized by

an Act of Congress.

The Bureau of Land Management (BLM) is

responsible for vast land areas on the North

Slope, including the National Petroleum Reserve,

NPRA. Habitat suitable for polar bear denning

and den sites have been identiﬁed within NPRA.

The BLM considers ﬁsh and wildlife values under

its multiple use mission in evaluating land use

authorizations and prospective oil and gas leasing

actions. Provisions of the MMPA regarding

the incidental take of polar bears on land areas

and waters within the jurisdiction of the United

States apply to activities conducted by the oil and

gas industry on BLM lands.

 The North Slope Borough Polar Bear Deter-

rence Program. The North Slope Borough

(NSB) Department of Wildlife Management

has maintained a polar bear hazing program

in Barrow and surrounding villages to protect

residents since 1992. Patrols have been a

collaborative effort by the NSB and the

Native Village of Barrow and Kaktovik. This

program has been very successful in Kaktovik

and Barrow in limiting the number of bears

killed in recent years due to public safety

concerns. Efforts to formalize training and

hazing programs have been an important step

in making the program successful. Continued

efforts are needed to implement training

programs annually, and to provide funds

needed to support the program.

In summary, existing international and domestic

agreements have been in place for 40 years to

guide the conservation and management of polar

bears. Their main strength to date has been to help

regulate the harvest and trade of polar bears, as

well as non-lethal take of bears. While these agree-

ments have addressed direct take of polar bears,

they are currently insufﬁcient to reduce the main

threat to polar bears- the range wide loss of their

sea ice habitat. However, they remain an important

foundation on which to implement this Plan.

80 Polar Bear Conservation Management Plan

Appendix A—Background

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50pp.

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Polar Bear Conservation Management Plan 91

Appendix B—Speciﬁc Conservation and Recovery Actions Considered

APPENDIX B— SPECIFIC CONSERVATION AND RECOVERY ACTIONS CONSIDERED

Proposed Actions — The entries below were proposed by Recovery Team members during development

of the Plan; categorized as action, education or research; and used to develop and reﬁne the high priority

conservation and recovery actions that appear in the Plan text.

Proposed Actions — Support international conservation efforts through the range states relationships

(Action) Participate in circumpolar efforts to reduce human-bear conﬂicts.

(Action) Participate in circumpolar efforts to track and reduce international illegal trade in polar bears

and polar bear parts.

Proposed Actions — Manage human-bear conﬂicts

(Action) Convene a community-based working group – including whaling captains — to explore options

for managing bone piles. Develop best management practices that can be shared with communities.

(Action) Remove or disperse bone piles to reduce bear concentrations (i.e., reduce risk of harmful impacts

from disease transmission, oil spills).

(Action) Develop and share best practices for managing bear viewing to minimize impacts on polar bears

and potential human-bear conﬂicts. Build on existing efforts, e.g. NSB program.

(Research) Assess the highest temporal/spatial risk areas for negative human-bear encounters. Monitor

changes in the human-bear interactions hotspots/focal points.

(Action) Develop emergency response plans for extreme events such as mass bear strandings, low

immune response to pathogens, and an absence of whale carcasses at Kaktovik.

(Research) Monitor effectiveness of deterrence programs, collect data to differentiate cause of bear

deaths, and analyze polar bear mortalities.

(Action) Scholarship programs/work with ANSEP/Ilasagvik College to develop professional bear

expertise in local communities.

(Education) Work with local residents and other experts to effectively communicate the importance of

minimizing human-bear conﬂicts.

(Research/Education) Standardize a community-based monitoring & data management program for polar

bears and for human-bear conﬂicts. Engage residents, industry, researchers, NGOs and others living &

working in Arctic. Communicate what is being monitored and why. Share the results.

(Education) Work with local residents to communicate the value of reporting human-bear interactions.

Proposed Actions — Collaboratively manage subsistence harvest

(Education) Develop clear, understandable materials for conveying harvest management principles;

include clariﬁcation of the various interpretations of the term “sustainable.” Update existing information

for user-group audiences.

(Action) Pass on knowledge to future generations regarding responsible and effective hunting and harvest

management.

(Action) Implement Chukchi harvest quota in U.S. (US/Russia bilateral agreement).

(Action) Work with Russian colleagues to implement Chukchi harvest quota in Russia.

(Research) Monitor input parameters needed to estimate maximum net productivity (i.e. within optimum

sustainable population).

(Education) Work with partners and subsistence users to communicate relationship between maximum

net productivity and harvest; if a subpopulation declines due to declining carrying capacity, subsistence

harvest will continue but harvest levels will go down.

(Research) Develop separate harvest rate estimates for male and female bears.

(Action) Consistent with existing agreements, prohibit all harvest of females with cubs.

92 Polar Bear Conservation Management Plan

Appendix B—Speciﬁc Conservation and Recovery Actions Considered

(Research) Ensure on-going, long-term, adequate basic monitoring of Chukchi Sea & SBS populations.

(Research) Support the on-going, long-term, and consistent monitoring of polar bears across the entire

range. (PBSG)

(Research/Monitoring) Improve subsistence harvest monitoring, e.g., tagging, genetic sampling, bio-

sampling etc.

Proposed Actions — Protect denning habitat

(Action) Protect polar bear travel corridors and seasonal habitat areas (e.g., barrier islands).

(Action) Create denning opportunities in prime habitat (i.e., barrier islands) through use of snow fences

to create snow drifts.

Proposed Actions — Minimize risk of contamination from spills

(Action) Improve spill response capability—deterrence, rescue & handling of oiled bears. Train local

community members as ﬁrst responders. Stage equipment and supplies in villages.

(Action) Minimize risk of oil spills (e.g., collaborate with Industry and other regulatory agencies on better

inspections and maintenance of pipelines, production facilities, etc.).

(Action) Work with Arctic Council, Russia, USCG, and others on improving spill response plans for

Chukchi and Southern Beaufort Seas.

(Research) Map current and future overlap of bear distribution with resource extraction activities.

Proposed Actions — Effects of shipping

(Research) Study the effects of shipping on bears.

(Action) Encourage greater Coast Guard presence in Arctic (Arctic Marine Mammal Commission is

working on this issue).

(Action) Support the commercial ﬁshing moratorium north of the Bering Straits until marine mammal

management protection plans and mitigation measures are in place.

(Action) Ratify law-of-the-sea treaty

(Action) Expand observer program on ships to document marine mammal interactions. Engage and train

local communities to staff such a program.

(Action) Work with international partners to improve off-shore development & shipping regulations to

minimize potential impacts on bears, especially with Russia and Canada.

Proposed Actions — Effects of Contaminants

(Research) Monitor contaminants and their effects on bears through harvest monitoring programs and

minimally invasive sample collection from live animals; potential partners include Range States.

(Action/Education) Reduce potential for exposure from acute, lethal contaminant exposure (e.g., ethylene

glycol).

(Action) Develop, assess, update best practices for handling contaminants, and responding to inadvertent

exposures.

(Action) Manage landﬁlls via fencing and other actions to reduce exposure to contaminants.

(Research) Assess current contaminant threat to bears and where the greatest risks are.

(Action) Clean up legacy oil wells.

(Research/Action) Determine whether contaminant levels in polar bears have implications for human

consumption (food safety, food security).

Proposed Actions — Effect of research impacts

(Action) Evaluate and manage the cumulative effects of research on polar bears.

Polar Bear Conservation Management Plan 93

Appendix B—Speciﬁc Conservation and Recovery Actions Considered

(Action) Evaluate speciﬁc research protocols by examining value to polar bear conservation and direct

impact on bears. i.e. cost-beneﬁt analysis.

(Action) Develop safe-handling protocols for polar bears.

Research Actions — The entries below were proposed by Recovery Team, Science and TEK workgroup

during development of the Plan. The list consists of representative projects supporting research areas

identiﬁed in Plan. Implementation of these or of other projects will ﬂow from the dynamic and adaptive

process associated with implementing and updating the Plan.

Population dynamics and distribution. Information on population dynamics and distribution informs most

aspects of wildlife management, including subsistence harvest and human-bear interactions, and is key to

understanding current and future conservation status. The ecological dependence of polar bears on sea-ice

as a platform from which to access energy-rich marine prey has shown for some populations that changes in

the physical sea-ice environment can induce declines in population vital rates, and thus must be considered

when evaluating future persistence. Because of this, long-term studies of subpopulation status, including

the vital rates used as demographic recovery criteria, are needed to measure progress towards persistence-

based goals. Research and monitoring on the two polar bear subpopulations shared by the U.S suggests that

physical and biological differences between populations may affect how polar bears respond to habitat loss,

especially in the near term, underscoring potential spatial and temporal variation in the response of polar

bears to climate change.

Research actions — Population dynamics and distribution

1. Estimation of population status and trend:

a. via estimation of demographic parameters including population size, population growth rate,

survival, and recruitment, or indices of these parameters.

b. via biological and ecological indices.

c. via the sex, age, and reproductive composition of human-caused removals.

2. Determine current distribution of populations and implications for population size estimation, harvest

allocation, and meta-analysis of data from overlapping populations.

3. Evaluate the mechanistic relationships between sea-ice, prey abundance, and polar bear vital rates

over timeframes relevant to the Conservation Management Plan.

4. Estimate the numbers of bears coming on shore in late summer and assess differential survival and

ﬁtness for bears that spend time on shore versus remaining on sea-ice.

a. Expand onshore non-invasive genetic sampling,

5. Monitor the level and type (e.g., sex and age) of human-caused lethal removals

6. Develop models to evaluate future population status and management actions, perform sensitivity

analysis with respect to management actions, perform risk assessments with respect to human-caused

removals, and identify key information needs.

a. Develop a standardized and adaptive approach for estimating sustainable harvest rates,

communicating the risks and tradeoffs of different harvest strategies to managers, and evaluating

the effects of harvest on population status.

7. Analyze optimal study design, sample size, and spatial and temporal distribution of sampling effort to

answer key demographic questions; perform cost-beneﬁt analyses.

8. Evaluate emerging technologies (e.g., high-resolution satellite imagery and other technological

advancements) for integration into existing monitoring plans.

9. Develop effective and less-invasive research and monitoring techniques.

10. Evaluate circumpolar patterns in genetic, behavioral, life-history, and ecological diversity for polar

bears in relation to the groupings of polar bears considered in FG2.

11. Improve our understanding of why polar bear populations differ in their response to sea-ice loss

and based on that understanding identify representative populations in different ecoregions for

monitoring responses to sea-ice loss.

94 Polar Bear Conservation Management Plan

Appendix B—Speciﬁc Conservation and Recovery Actions Considered

12. Improve our understanding of the physiological response of polar bears to environmental and

anthropogenic stressors and develop methods for monitoring those responses.

Habitat ecology. Understanding how bears respond to functional changes in their environment is necessary

to predict the consequences of loss of sea-ice habitat to population status, distribution, and ultimately the

likelihood of persistence. Improving our understanding of the links between environmental change and

polar bear persistence will allow decision-makers to determine future policies regarding the chances of

enhancing persistence.

Research actions— Habitat Ecology.

1. Improve our understanding of the environmental and biological characteristics (e.g., bathymetry,

ice concentration, benthic productivity) of important polar bear habitats, identify key habitat areas

(including denning areas), and projected future availability of habitats.

a. Incorporate resource selection information from prey species into analyses

2. Determine the behavioral and demographic responses of polar bear prey, primarily ringed and

bearded seals, to sea-ice loss and changes in late-winter and spring snow depths on the sea-ice.

Evaluate whether such responses affect the accessibility of prey to polar bears.

3. Identify the ecological mechanisms by which polar bears are responding to sea-ice loss to improve

short-term and long-term projections of population-level responses.

4. Determine the relationship between sea-ice conditions, the proportion of bears using land, and the

duration of time spent there. Develop predictions for the rate at which increased numbers of bears

may occur onshore and the necessary management responses.

5. Characterize the spatial overlap of activities and the potential response of polar bears to on- and off-

shore resource exploration and extraction activities.

a. Study potential disturbance of polar bears by shipping and other development activities, with

attention to high-use areas such as the Bering Strait

b. Evaluate data submitted on observations of polar bears in the oil ﬁelds to detect spatial and/or

temporal changes

6. Model the distribution of large- and small-scale oil spills relative to on- and off-shore habitats and

polar bear distribution. Evaluate potential effects of spills on the availability of suitable habitat.

7. Use local observations and traditional ecological knowledge to evaluate seasonal distribution patterns

and polar bear behavior, including denning and movements.

a. Standardize objectives and methods for community-based monitoring

8. Continue and expand den detection, mapping, and monitoring activities throughout the range of polar

bear population in Alaska.

9. Model and forecast cumulative impacts on polar bears using a Bayesian Network approach.

Health and nutritional ecology. An individual’s health reﬂects the interaction between its behavioral choices

and the environment. Because of this, measuring changes in health over time has great potential for

revealing important associations between environmental stressors and population dynamics.

Research actions— Health and Nutritional Ecology.

1. Determine if polar bears are being increasingly exposed to diseases and parasites and the potential

impact of disease on body condition, reproduction, and survival.

2. Characterize baseline exposure to hydrocarbons, atmospherically-transported contaminants, and

industrial pollutants associated with resource extraction practices.

3. Evaluate methods to decontaminate oiled polar bears

4. Characterize the physiological stress response of polar bears relative to life history, physiological

states, and environmental conditions, and determine if a relationship exists between stress responses

and measures of body condition and reproduction.

5. Improve our understanding of the relationships between polar bear feeding ecology and behavior,

body condition and food intake, demography, and sea-ice availability.

Polar Bear Conservation Management Plan 95

Appendix B—Speciﬁc Conservation and Recovery Actions Considered

6. Evaluate the potential cumulative impacts of research, hunting, industry, tourism activities on polar

bear health, behavior, and vital rates

Nutritional and cultural use of polar bears. Historically, native communities throughout the coastal arctic

have relied upon polar bears as both a nutritional and cultural resource. Research, including through

Traditional Ecological Knowledge, may help to better understand the cultural and nutritional signiﬁcance of

polar bears to communities that have historically relied upon them, and how climate change may affect the

use of polar bears as a renewable resource in the future.

Research actions— Nutritional and Cultural Use of Polar Bears

1. Periodically assess key community perspectives, values and needs regarding: human-polar bear

interactions, sustainable use of polar bears, and incentives associated with polar bear harvest. Also,

evaluate the cultural and traditional uses of polar bears.

a. Evaluate the cultural effects of harvest management decisions

b. Return to key communities to verify and present ﬁndings

2. Evaluate the use of polar bears from human nutritional health and food security perspectives. (e.g.,

dietary quality of polar bear in comparison to store bought meat, implications of the presence and

potential effect(s) of contaminants in the meat).

a. Evaluate the effects of restrictions/quotas on the food security and nutritional status of coastal

native communities

b. Evaluate the inﬂuence of harvest management on the availability, types, and quality of food

resources

3. Ongoing polar bear health assessments through samples and observations by local communities and

hunters. Combine polar bear sampling program as part of larger marine arctic ecosystem and other

marine mammal sampling (e.g., ice seal biomonitoring).

a. Analyze hunter samples

b. Analyze agency capture samples

c. Compare results to global polar bear health studies

Human-polar bear interactions. There is poor understanding of how conﬂict affects polar bear populations

and concomitantly how conﬂict affects humans living and working in polar bear range. The goal of this

work is to better understand the dynamics of human-polar bear conﬂict by gaining insight about potential

drivers of interaction and conﬂict. This information is needed so that mitigation actions can be developed,

implemented, and evaluated.

Research actions— Human-Polar Bear Interactions

1. Collect, process, and synthesize all existing records of human-polar bear interactions to gain insight

on the quality of conﬂict records, spatial and temporal trends in conﬂicts, severity of conﬂict, potential

biases in conﬂict reporting, and types of management strategies used to mitigate conﬂict.

a. standardize operating procedures for polar bear patrols and the reporting methods used to

document human-bear conﬂicts

b. maintain central database (i.e., Polar Bear Human Information Management System)

c. monitor the effectiveness of all deterrence programs including non-lethal methods used in

Chukotka

2. Characterize environmental, spatial, and anthropogenic factors that contribute to human-polar bear

conﬂict around industrial activity centers and villages.

a. develop best practices for polar bear viewing and ecotourism

b. develop best practices for attractant management (e.g., ice cellars, dumps, drying racks, dog lots)

3. Develop models for predicting the risk of human-polar bear conﬂict given scenarios of environmental

change, increased use of terrestrial habitat, and increased anthropogenic activities.

96 Polar Bear Conservation Management Plan

Appendix B—Speciﬁc Conservation and Recovery Actions Considered

4. Evaluate the effects of concentrated attractants (e.g., dumps) and supplemental feeding (e.g., remains

of subsistence-harvested whales) on polar bear distribution, habitat use, nutritional status, and

human-bear interactions.

5. Expand non-invasive genetic sampling around seasonally abundant, concentrated food sources (e.g.,

bone piles).

Polar Bear Conservation Management Plan 97

Appendix C—Population Dynamics and Harvest Management

APPENDIX C—POPULATION DYNAMICS AND HARVEST MANAGEMENT

The harvest strategy described in the Conservation

Management Plan is founded on an extensive

literature on harvest theory (Wade 1998, Runge et

al. 2009) and a detailed population model for polar

bears (Regehr et al. 2015, Regehr et al. in press),

and is customized to reﬂect the cultural practices

of Alaska Native people and the principles of the

Marine Mammal Protection Act. This Appendix

describes the underlying harvest theory and techni-

cal details of the harvest strategy.

Harvest Theory

Sustained removal of animals from a population,

whether for subsistence harvest, sport harvest,

incidental take, or population control, is possible

because of density-dependent feedback mechanisms.

A reduction in the population size via removals

can—through any of a number of processes—free

up resources (food, space, breeding territory, etc.)

for the remaining individuals, increasing their

survival rates, reproductive rates, or both. The

increase in the demographic rates provides a surplus

of individuals relative to what is needed to maintain

the population at a constant size. This surplus can

be sustainably removed, as long as a number of

conditions are met.

The simplest model that can capture these popula-

tion dynamics is the discrete logistic model, which

describes the trajectory of a population using the

formula,





= 



+ 



1 











(C1)

where N

is the population size at time t, r is the

intrinsic rate of growth of the population, K is the

carrying capacity, and h is the rate of removal (the

harvest rate). If such a population is subjected to a

ﬁxed rate of removal for some period of time, it will

eventually settle to an equilibrium population size





= 1 







(C2)

that allows a sustained annual removal (annual

harvest) of a number of individuals as calculated by

the formula:





= 



= 1 





= 







(C3)

Plotting H

against N

depicts a “yield curve”

(Fig. C-1). For a given harvest rate, h, there is a

corresponding equilibrium population size and

annual harvest. The yield curve traces the combina-

tions of N

and H

: when h = 0, N

= K and

the annual harvest is, of course, 0. As h increases,

decreases and H

increases until a maximum

sustainable annual harvest is reached. (For the

discrete logistic model, this maximum occurs at h =

r/2, N

= K/2, and H

= rK/4.) The harvest rate

can continue to increase, pushing the equilibrium

point over to the left side of the yield curve; now N

continues to decrease, but so does H

. When h ≥ r,

= 0, that is, the harvest rate is greater than the

fastest-possible population growth rate, and the only

resulting equilibrium condition is extirpation of the

population.

0 K

Annual Harvest (H)

Population Size (N)

Figure C-1. The yield curve for a population that is described

by a discrete logistic population model. If the annual harvest

is a ﬁxed fraction, h, of the population size (black line), the

population size will converge to a stable equilibrium point.

When the harvest rate is ﬁxed, the equilibrium point

is a stable attractor for the population dynamics:

if the population size is lower than N

, the surplus

production (as indicated by the yield curve) will be

greater than the annual harvest (which occurs on

the thin black line), and the population will increase

back toward N

; if the population size is greater

than N

, the annual harvest (on the black line) will

exceed the surplus production, and the population

will decrease back toward N

. The stability of the

equilibrium point is the reason that using a sustain-

able, ﬁxed harvest rate is a robust strategy—the

population dynamics are self-correcting in the face

of stochastic ﬂuctuations. The critical thing to note,

however, is that this stability works for a ﬁxed

harvest rate (i.e., percentage of current population

size), not a ﬁxed harvest quota (i.e., a ﬁxed number

of individuals removed each year, regardless of

changes in population size). To achieve a ﬁxed

harvest rate, the harvest quota needs to be able to

change in response to changes in the population size

on a regular basis.

98 Polar Bear Conservation Management Plan

Appendix C—Population Dynamics and Harvest Management

The population dynamics described above and the

stability of the ﬁxed-rate removal strategy depend

on a few assumptions: ﬁrst, that the environment

remains constant on average (the mean r and mean

K do not change); second, that changes in N can

be monitored without bias and used to adjust the

number of animals removed; third, that there are no

Allee effects, or at least that the population never

drops low enough that they are realized; and fourth,

that eq. C1 adequately describes the dynamics. Note

that although the model in eq. C1 looks determin-

istic, it can also serve as the central tendency of a

stochastic model, and under reasonable assumptions

about the nature of the annual variation, the ﬁxed-

rate removal strategy will still robustly maintain

a stochastic population near an equilibrium point,

provided there is not also some change in the

environment.

The effect of environmental change on the yield

curve

What happens to the yield curve (and the harvest-

able surplus) if the environment changes? It’s

not easy to see the answer to this question in the

formulas for the discrete logistic model, because

the underlying density-dependent processes are

not explicitly written out in the formula. Instead,

consider the following population model,



+1

= 



(

1 + 



)

−ℎ



(C4)

where

is the survival rate and R is the recruitment

rate (the number of offspring produced per adult).

Let’s assume that the survival rate,

, is density

independent (this can be a reasonable simplifying

assumption for the adults of a large, long-lived

mammal species). But let recruitment be density

dependent and given by the linear function





= + 



(C5)

where a is the reproductive rate at very low densi-

ties (when there is no competition for resources),

and b < 0 describes how much recruitment

decreases for each unit increase in the population

size. Then, substituting eq. C5 into eq. C4,



+1

= 



(

1 + + 



)

−ℎ





(

1 + 

)





+ 



−ℎ



(C6)

Now, by comparing eq. C6 to eq. C1 and making the

following substitutions,



(

1 + 

)

= 1 + 

, and

= − 

⁄

(C7)

we calculate





(

1 + 

)























+ 



1 











(C8)

which is identical to eq. C1. Thus, this new model,

built from the underlying density-dependent

relationships, is identical to the discrete logistic

model. What’s helpful about this is that we can use

the substitutions in eq. C7 to solve for the param-

eters of the discrete logistic (r and K) in terms of the

parameters in the density-dependent formulation (a,

b, and

= 

(

1 + 

)

−1

=

1 −

(

1 + 

)



(C9)

A graphical depiction of the model in eq. C4 gives

an intuitive sense of why it has the same behavior as

the model in eq. C1 (Fig. C-2). In a population that

is below its carrying capacity, the reproductive rate

will exceed the level needed to offset mortality, so

the population will grow. As the population grows,

competition for resources increases, and the repro-

ductive rate decreases. When the reproductive rate

matches the mortality rate, there is a stable equilib-

rium point (K

). Suppose now that there is a change

in the environment such that the extent of habitat

decreases, but the habitat that remains is the same

quality as before. In this case, we could reason that b

will decrease, because the competition for resources

will be felt sooner as the population grows; but a will

stay the same, because the reproductive rate at very

low density would remain unchanged (Fig. C-2, top

panel). The equilibrium point at which reproduction

offsets mortality decreases (K

Another way in which the environment could change

is that the extent of habitat doesn’t change, but

the quality of it decreases. In this case, we might

surmise that the reproductive rate decreases equally

for all densities (Fig. C-2, bottom panel), thus a

decreases, but b stays the same. Again, the equilib-

rium point at which reproduction offsets mortality

decreases (K

Although the effect of these two types of envi-

ronmental change on the carrying capacity looks

similar, the effect on the yield curve is profoundly

different (Fig. C-3). In the case of the effect of

habitat quantity, b changes but not a; looking at

eq. C9, this means that the carrying capacity (K)

changes, but the intrinsic rate of growth (r) does not.

Thus, the yield curve shrinks to the new carrying

capacity, but does not change its proportions (Fig.

Polar Bear Conservation Management Plan 99

Appendix C—Population Dynamics and Harvest Management

C-3, aqua curve). On the other hand, in the case of

the effect of habitat quality, the change in a affects

both K and r; the yield curve becomes ﬂatter as

well as smaller (Fig. C-3, purple curve). These two

changes will affect harvest management differently.

In the case of the habitat quantity change (change

in b only), the ﬁxed harvest rate strategy (using the

desired harvest rate from before the change) will

still work, and will maintain the population at the

same proportion of its carrying capacity as it did

previously, because only K (but not r) is affected. In

the case of the habitat quality change (change in a),

the ﬁxed harvest rate strategy that worked before

the environmental change will no longer hold the

population at the same proportion of K and might

not even be sustainable. Thus, the demographic

mechanism of environmental change matters to the

management of harvest.

0 K

Annual Harvest

Population Size

Original reproductive rate

Loss of habitat quantity

Loss of habitat quality

Figure C-3. The effect of environmental change on the yield

curve, for a discrete logistic population model.

A note about the intrinsic rate of growth

In the models described above, the intrinsic rate

of growth (r) is the growth rate the population

would have if its density were close to 0; that is,

it is a descriptor of the underlying dynamics of a

particular population in a habitat of a particular

quality. Further, eq. C9 shows that the intrinsic

rate of growth for a particular population could

change, if the survival rate or the reproductive rate

at low density changed as a result of changes in the

environment. Thus, the way we are using the term,

the intrinsic rate of growth is not a property of

the species as a whole (i.e., it is not the theoretical

maximum growth rate that the species could experi-

ence under the best possible conditions).

Maximum Net Productivity Level

The phrase “maximum net productivity level”

arises from language in the MMPA, but invokes

the population theory described by yield curves.

The maximum net productivity is “the greatest

net annual increment in population numbers or

biomass resulting from additions to the population

due to reproduction and/or growth less losses due

to natural mortality” (50 CFR 403.02); this annual

increment corresponds to the surplus production

that allows annual harvest, thus, the maximum

net productivity is the value on the y-axis that

corresponds to the peak of the yield curve (Fig.

C-1). The maximum net productivity level, then,

is the population size (the value on the x-axis) that

corresponds to this peak.

The harvest theory derivations shown above

demonstrate that the equilibrium population size

that produces the greatest sustainable annual

harvest will change if the underlying demographic

dynamics change. The policy distinction between

MNPL (referenced to a historic value K

that could

potentially be reduced by habitat effects) and mnpl

Figure C-2. Density-dependent demographic rates, carrying

capacity, and environmental change. As the population size

increases, the density-dependent reproductive rate decreases

until is just matches the mortality rate; at this point, additions

and subtractions from the population are equal and the popula-

tion size is stable (K

). Changes in the environment that affect

the reproductive rate (here we assume a negative effect) can

shift the carrying capacity to a new level (K

), either through an

effect on habitat quantity (top panel) or through an effect on

habitat quality (bottom panel).

0.0

0.1

0.2

0.3

0.4

0 K

Demographic Rate

Population Size

0.0

0.1

0.2

0.3

0.4

0 K

Demographic Rate

Population Size

Original reproductive rate

Loss of habitat quantity

Loss of habitat quality

Mortality rate

100 Polar Bear Conservation Management Plan

Appendix C—Population Dynamics and Harvest Management

(referenced to a new value K

that has been reduced

by habitat effects) discussed in section III.b in the

Plan is centered around whether the MMPA term

“maximum net productivity level” refers to the

peak of the historical yield curve (MNPL) or the

peak of the altered yield curve (mnpl). Taking into

account the unique circumstances of polar bears and

in an effort to advance conservation of polar bears,

we have adopted the mnpl interpretation, for the

reasons explained in the body of the Plan. MMPA

Demographic Criterion 2 requires that total human-

caused removals do not exceed a rate h (relative to

the subpopulation size) that maintains the subpopu-

lation above mnpl. The remainder of this Appendix

discusses some of the technical considerations in

evaluating this criterion.

It is important to note that MMPA Demographic

Criterion 2 focuses on a human-caused removal

rate, not a ﬁxed quota. Fixed-rate harvest, and

by extension variable-rate harvest under a state-

dependent framework (Regehr et al. 2015, Regehr

et al. in press), has a sound basis in theory and

practice (Hilborn and Walters 1992), including for

management of polar bears (Taylor et al. 1987).

Further, it can be responsive to changing conditions,

notably, a changing carrying capacity (Walters and

Parma 1996). If a subpopulation declines because of

a decline in carrying capacity, in the absence of other

legal constraints

, take can continue but absolute

take levels would decline. For example, at a ﬁxed

removal rate of 4.5% (Taylor et al. 1987), subpopula-

tion sizes of 800 and 400 would lead to removal levels

of 36 and 18 bears per year, respectively. The key

to managing with a ﬁxed removal rate is ongoing

monitoring of the population size, the annual

take, and the demographic parameters that affect

the intrinsic population growth rate (to evaluate

whether the mean value of r remains unchanged).

Further, to ensure that the criterion is met with high

probability, the data quality and precision must be

taken into account (Regehr et al. 2015, Regehr et al.

in press). Such a management program calls for the

collaborative partnership of Alaska Native entities

and federal agencies.

The U.S.-Russia bilateral agreement concerning

management of the Chukchi Sea subpopulation

deﬁnes a sustainable harvest level as a “harvest level

which does not exceed net annual recruitment to the

population and maintains the population at or near its

current level, taking into account all forms of removal,

and considers the status and trend of the population,

based on reliable scientiﬁc information.” In most cases,

this deﬁnition of sustainable take is more conservative

(it restricts take more) than the proposed approach to

take in this Plan. Thus, management of human-caused

removals in the Chukchi Sea under the pre-existing

bilateral agreement is also likely to meet the criteria for

human-caused removals under this Plan.

The speciﬁc demographic thresholds referenced

in the Plan are initial proposals; further work is

being undertaken to reﬁne them, and they should

be revised over time as additional data become

available. Further, the risk tolerance associated with

uncertainty in the estimates of these thresholds

has not yet been established; there should be a

high probability that the actual rate of take is less

than or equal to the rate needed to achieve mnpl,

but further deliberation is needed to establish what

size buffer is needed to account for uncertainty in

estimates of abundance and removal rate, and still

produce reasonable performance relative to both

Fundamental Objectives 3 and 4 (see Regehr et al.

2015).

Maximum net productivity level and structured

populations

The discrete logistic population model (eq. C1) is a

simpliﬁed representation of population dynamics

and leaves out a number of properties that are

important in the context of polar bears. One of these

properties is the structure of the population, as

described by the age, sex, and size of the individuals.

Long-lived, large mammals have a relatively late

age of ﬁrst reproduction and the reproductive rate

can vary with age. The individuals in the younger

age classes do not breed and can be more vulnerable

to mortality factors. Animals of different sexes may

be different sizes and require different amounts of

resources. These patterns have been studied exten-

sively in bears; survival, mortality, and reproduction

vary signiﬁcantly by age and sex. As a result, the

density-dependent dynamics in such populations

are often non-linear, and the yield curve reﬂects

additional ability to compensate for removals. A

modiﬁcation to the logistic model that captures some

of these dynamics is known as the

-logistic model,

described by





= 



+ 



1 















(C10)

where the parameter

controls the non-linearity in

the dynamics. The population size that produces the

greatest net productivity (annual harvest) is







= = 

1 + 



/

, (C11)

which occurs when the harvest rate is

ℎ





1 + 

. (C12)

Polar Bear Conservation Management Plan 101

Appendix C—Population Dynamics and Harvest Management

Thus, the effect of an increasing

on the yield curve

is to increase the maximum yield and to shift the

yield curve to the right, so that the peak (mnpl)

occurs closer to the carrying capacity (Fig. C-4).

0 K

Annual Harvest

Population Size

= 2

= 1

= 3

= 5

Figure C-4. Yield curves for a

-logistic population model. The

four curves share the same carrying capacity (K) and intrinsic

rate of growth (r), but differ in the

parameter.

The polar bear population model described by

Regehr et al. (2015) and Regehr et al. (in press)

explicitly accounts for the age- and sex-structure

of the population, as well as non-linearity in the

density-dependent relationships, so it is much

more detailed than the

-logistic model, but the

yield curve is roughly approximated by a

-logistic

model with r = 0.07 and

= 5.045. It is the intent

of the Plan that MMPA Demographic Criterion 2 be

assessed with a population model that incorporates

the best available scientiﬁc information about polar

bears at the time of assessment; such a model should

account for the shift in the yield curve brought about

by population structure and non-linear dynamics.

Maximum net productivity level and selective

harvest

The removal rate that achieves MMPA Demo-

graphic Criterion 2, h, depends on the underlying

demographic rates for the subpopulation, the sex

and age composition of the subpopulation, as well as

the sex and age composition of removals. A valuable

reference point is the removal rate, h

mnpl

, that

achieves mnpl at equilibrium when removals are in

direct proportion to the sex and age composition of

the subpopulation (i.e., when removals do not select

for certain sex or age classes of animals).

In practice, the removal rate h can be different from

the reference rate h

mnpl

for a variety of reasons.

For example, it is possible to adjust h based on the

sex and age class of bears removed to allow for a

2:1 male-to-female ratio in the removals (Taylor

et al. 2008), based on biological (e.g., the different

reproductive value of females vs. males) or manage-

ment considerations. The intent of Demographic

Criterion 2 is to establish mnpl on the assumption

of asymptotic population dynamics and unbiased

removals, and then to ensure that the actual remov-

als, whether biased or unbiased with regard to sex

and age of the individuals removed, maintain the

subpopulation size above mnpl.

For the purposes of this Plan, several details about

the interpretation of mnpl are speciﬁed. First, mnpl

is understood to be proportional to the carrying

capacity. If the carrying capacity changes, whether

owing to anthropogenic or non-anthropogenic

causes, mnpl changes in proportion. Second, mnpl is

calculated by assuming that removals are unbiased

with regard to age and sex of polar bears, that is,

polar bears of different ages and sexes are removed

in proportion to their relative abundance. Third, the

proportions of actual removals need not be unbiased

with regard to age and sex, provided that the total

population size relative to the carrying capacity, as

speciﬁed by mnpl, is achieved. These interpretations

of mnpl represent the views of USFWS for the

purpose of conserving polar bears. This approach

does not necessarily preclude other approaches to

determining the maximum net productivity level in

other conservation plans.

The Compatibility of Harvest with

Conservation and Recovery

It is not unusual to authorize incidental take of a

species protected under either the MMPA or the

ESA, and the standards for such authorization are

well described and well implemented. It is, however,

much less common to purposefully seek to harvest

species that need the protections of the ESA or

the MMPA, but it does occur in a small number of

special cases. Subsistence harvest of polar bears for

a variety of cultural purposes is a central tradition

for Alaska Native people, as well as other native

Arctic peoples. The ESA and MMPA both recognize

the importance of subsistence harvest for Alaska

Native people. In fact, both laws allow certain

subsistence harvest by Alaska Native people even

when a species is “threatened” or “depleted.” In this

Plan, we recognize continued subsistence harvest

as a fundamental goal associated with polar bear

conservation and recovery. We also provide condi-

tions for harvest to ensure (i) under the ESA, that

harvest does not appreciably reduce the likelihood

of survival or recovery; and (ii) under the MMPA,

that harvest does not affect our ability to achieve the

conservation goals of the Act.

But the question remains, how can harvest be

compatible with the conservation and recovery of a

species that is expected to decline throughout parts

of its range in the near- and mid-term? In this Plan,

102 Polar Bear Conservation Management Plan

Appendix C—Population Dynamics and Harvest Management

we address both the scientiﬁc and conservation basis

for maintaining such harvest opportunity.

There are many ways that changes in the environ-

ment could affect polar bear population dynamics

and harvest opportunity; we consider two scenarios

here to illustrate the considerations that this Plan

recommends for management of removals. In

the ﬁrst scenario (“habitat quantity”), reduction

in the extent of the sea-ice platform may reduce

access to prey and create a greater competition for

resources, reducing the carrying capacity. But if

some bears are able to access prey, and thus retain

high survival and reproductive rates, the intrinsic

population growth rate might remain the same,

even if the overall population number declines. In

this situation, harvest can be maintained if the total

rate of human-caused removals remains at or below

h (the removal rate that maintains a population

above its mnpl). Annual quotas for human-caused

removal would need to be reduced in proportion

to the decrease in the population size, but the rate

of removal could remain the same. For example, if

the removal rate was 3.0% and the subpopulation

size was 2,000, up to 60 bears could be taken; if the

subpopulation size was only 1000, no more than

30 bears could be removed while meeting MMPA

Demographic Criterion 2. This would maintain the

population size at roughly the same ratio relative

to changing carrying capacity, even as the carrying

capacity decreased (Fig. C-5, top panel).

In the second scenario (“habitat quality”), an

increase in the ice-free period could, for example,

increase the fasting period for all bears, reducing

reproductive rates (and possibly also survival rates)

across the board. In this case, the intrinsic popula-

tion growth rate and population resilience would

decrease. If this happened, the rate of harvest would

need to decrease to meet MMPA Demographic

Criterion 2. For example, if the intrinsic population

growth rate is 7%, then an appropriate removal rate

might be 4.5%; but if density-independent effects

of climate change caused the intrinsic population

growth rate to fall to only 2%, then the removal rate

necessary to maintain the population size above

mnpl would have to be below 1.5% (Fig. C-5, bottom

panel). If the intrinsic growth rate is negative, then

a population is incapable of maintaining its current

size or growing. In this case, there is no removal

rate that can meet MMPA Demographic Criterion

2 and ESA Demographic Criterion 4 (thus, h is 0);

indeed, the population would be expected to become

extirpated even in the absence of harvest.

In reality, some combination of these two effects is

also possible. In addition, the precise mechanisms by

which climate change effects will affect polar bears

are not well understood at this time. Research and

monitoring will clarify these issues. But the Plan’s

MMPA and ESA criteria relative to human-caused

removals take into account both potential mecha-

nisms for the effects of climate change on polar bear

populations. The framework for management of

human-caused removals will need to be responsive

to changes in both the growth rate and carrying

capacity. But, provided that the growth rate remains

positive, a sustained opportunity for removal

remains possible, even with a decline in carrying

capacity. Provided that climate change—the threat

that is driving the changes in growth rate and

carrying capacity—is addressed to the extent

described in this Plan, the framework established in

this Plan would allow for recovery under the ESA

and conservation under the MMPA.

The concepts underlying this framework for

management of human-caused removals are founded

in harvest theory (Wade 1998, Runge et al. 2009) and

can be illustrated with yield curves. Yield curves

show the annual total removals and the correspond-

ing equilibrium population size for a range of

sustainable harvest rates (Fig. C-5). The peak of the

yield curve is the maximum net productivity, and

removals that keep the population above mnpl will

fall somewhere on the right shoulder of the yield

curve. An impact on habitat quantity will shrink

the yield curve by reducing the carrying capacity

(Fig. C-5, top panel), while otherwise allowing the

same rate of removal (although the allowable quota

decreases). An impact on habitat quality will ﬂatten

the yield curve by reducing the intrinsic growth

rate (Fig. C-5, bottom panel), thereby reducing the

allowable rate of removal as well as the allowable

quota.

In principle, the strategy for managing human-

caused removals described above could work even

if the carrying capacity decreased to low levels,

but at some point, additional considerations would

arise, including the increasing risk of chance events

(stochasticity) on small populations and the possibil-

ity of Allee effects. Because of these considerations,

the Plan recommends a three-level approach to

management of human-caused removals, such that

the rate of removal would decrease as the risk to

the population of removal increased (red and yellow

zones of Fig. 8).

The framework for managing human-caused remov-

als also needs to be sensitive to the quality of data

that supports it, and to our ability to distinguish the

different mechanisms that might change the dynam-

ics. The management strategy described above is

predicated on being able to monitor the population

size and the number of removals on a regular basis,

ideally annually. Regehr et al. (2015) and Regehr

et al. (in press) show that as the sampling error

and interval between monitoring events increase,

removal is still possible, but the removal rate needs

to be set at a more cautionary level to guard against

dropping below mnpl. Further, changes driven by

Polar Bear Conservation Management Plan 103

Appendix C—Population Dynamics and Harvest Management

loss of habitat quantity as opposed to loss of habitat

quality will be difﬁcult to distinguish, yet they

have different effects on the sustainable level of

removal (Fig. C-5). The Plan recommends that these

considerations be included in the deliberations of

co-management groups as they establish guidelines

for removal of polar bears.

Historical K

Annual Harvest

Population Size

4.5%

3.0%

1.5%

r = 0.07

r = 0.049

r = 0.035

r = 0.020

removal rate

Historical K

Annual Harvest

Population Size

4.5%

3.0%

1.5%

Historical condition

K = 70% of historical

K = 50% of historical

removal rate

Figure C-5. The effects of reduced carrying capacity and

reduced growth rate on harvest yield curves. Each graph

shows the sustainable annual harvest against the correspond-

ing equilibrium population size; three reference lines show

removal rates of 4.5%, 3.0%, and 1.5%. The top panel shows

three scenarios where the carrying capacity changes, but

the intrinsic rate of growth remains the same (r = 0.07). The

bottom panel shows four scenarios where the intrinsic rate of

growth changes in the same proportion as the carrying capac-

ity. The graphs were derived using a theta-logistic population

model with

= 5.045, which roughly corresponds to dynamics

for polar bears (Regehr et al. 2015, Regehr et al. in press).

APPENDIX C — LITERATURE CITED

Hilborn, R., and C.J. Walters. 1992. Quantitative

Fisheries Stock Assessment: Choice, Dynamics, and

Uncertainty. Chapman and Hall, New York, New

York, USA.

Regehr, E.V., R.R. Wilson, K.D. Rode, M.C. Runge.

2015. Resilience and risk: a demographic model to

inform conservation planning for polar bears. U.S.

Geological Survey Open-File Report 2015-1029:1-56.

Regehr, E.V., R.R. Wilson, K.D. Rode, M.C. Runge,

H. Stern. In press. Harvesting wildlife affected

by climate change: a modeling and management

approach for polar bears. Journal of Applied Ecol-

ogy.

Runge, M.C., J.R. Sauer, M.L. Avery, B.F. Blackwell,

and M.D. Koneff. 2009. Assessing allowable take of

migratory birds. Journal of Wildlife Management

73:556-565.

Taylor, M.K., D.P. DeMaster, F.L. Bunnell, and

R.E. Schweinsburg. 1987. Modeling the sustainable

harvest of female polar bears. Journal of Wildlife

Management 51:811-820.

Taylor, M.K., P.D. McLoughlin, and F. Messier.

2008. Sex-selective harvesting of polar bears Ursus

maritimus. Wildlife Biology 14:52-60.

Wade, P.R. 1998. Calculating limits to the allowable

human-caused mortality of cetaceans and pinnipeds.

Marine Mammal Science 14:1-37.

Walters, C.J., A.M. Parma. 1996. Fixed exploitation

rate strategies for coping with effects of climate

change. Canadian Journal of Fisheries and Aquatic

Sciences 53:148-158.

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