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 CoChair) — 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 midterm 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 humancaused 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 nearand 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 subpopulations: the Chukchi Sea and the Southern Beaufort 

Sea. These 2 subpopulations have also been identified 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 unifying 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 throughout 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 accomplished by prompt and very aggressive reductions in 

worldwide GHG emissions, the probability of greatly 

reduced polar bear populations could be substantially 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 December 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 emissions 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 bestcase 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 unprecedented 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 immediate 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 

CO2 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 coastlines denote the level of agreement among the 6 models 

analyzed; greater uncertainty exists when fewer models 

agree. Inset shows the observed rise in atmospheric CO2

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 conservation, 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’ subpopulations. 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 conservation 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 subpopulations 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 stakeholders 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 aspirations, 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 ecoregions), 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 extinction 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 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)). 

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 distribution 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 acknowledge 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 recognized 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 subpopulation 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 humanpolar 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 conservation while minimizing restrictions to other activities 

within the range of the polar bear, including 

economic development.

Local, regional, state, national, and global communities benefit from human activities in the Arctic, 

including tourism, recreation, oil and gas development, 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 quantitative 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 population size is above the maximum net productivity 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 subpopulations 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 expectation 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 capacity, 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 conservation 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 ecosysPolar 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 twostandard 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 ecosystem 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.” Nevertheless, 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 considerations 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 indicators, 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 capacity, 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 (including 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 productivity 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 population 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 historical 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 capacity 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 subpopulation, 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 subpopulations 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 functional 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 fundamental 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 population 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 subpopulation size) that maintains the subpopulation 

above its maximum net productivity level 

relative to carrying capacity.

The removal rate that achieves MMPA Demographic 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, hmnpl, 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 hmnpl 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, 

hmnpl 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 “historical” conditions of polar bears in the context of the MMPA.

1	

0

1

2

3

4

5

6

7

8

9

1950 1960 1970 1980 1990 2000 2010 2020

September sea‐ice extent (106 km2)

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 available 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 fundamental level, both of the following criteria need to be met 

to achieve recovery of polar bears:

Recovery Criterion 1: the worldwide probability 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 provisions 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 determinations. 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 ranging 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 persistence 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 probabilities 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 variation 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 robustness, 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 pressing 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 recovery 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 population target. Rather, by focusing on the probability 

of persisting above the threshold, the criteria represent 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 subpopulation 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 demographic 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 population size, and will depend on the geographic distribution 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 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.

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 population size in the recovery unit) that maintains 

the population above its maximum net productivity 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 determine 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 humancaused 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 removals, 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 reproductive 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 conditions 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 establish 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 anthropogenic 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 interpretation 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 subpopulation 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 achievement 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 threatsbased 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; development 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 something 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 constitutes 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 compromising 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 Divergent 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 green30 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 CO2 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 important 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 aggressively 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 management. 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 mitigated 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 conservation goals, legal harvest that results in overutilization 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 humancaused mortality from other sources (Shadbolt et al. 

2012).

The subsistence harvest of polar bears, as represented 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 populations 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 additionally 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, humancaused 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 viability 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 significant 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 Criterion 2. This is the range in which ESA Demographic 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 probability 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, shipping, 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 associations, 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 populations 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 Fundamental Goals. 

Fundamental Goal 4, measurement scale: Cumulative 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 decreasing 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: Economic 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 unnecessarily 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 conservation 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 unfamiliar 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 productivity 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 enactment 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 Conservation 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 population.

Maximum net productivity level. The population size at which the net growth in the population (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 carrying 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 Size1	 Time Subpopulation Size

1	 Time Subpopulation Size

Carrying Capacity (K)

MNPL

Population Size

Stable Ecosystem Floor

Scenario

1 3 2

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 maximum 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 conservation 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 populations 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. Resilience 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 subsistence) 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 populations 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 populations take over. These dynamics include demographic 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 environmental 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

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 associated 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 population 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 (Fundamental 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	

0

Discretionary human‐caused

removal rate

(proportion of population size)

Population Status

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

h

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 reproductive rates, the mechanism and magnitude of densitydependence, 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 dynamics. 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 conservation 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 conservation 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 Implementation 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 Executive 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 decisionmaking body, although it may provide recommendations 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) HumanPolar 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 information on ongoing and planned research activities and 

also to identify priority areas for research initiatives 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 appropriately 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 recommendations. 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 Communication 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 Management 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 fundamental goals of this Plan:

 Limit global atmospheric levels of 

greenhouse gases to levels appropriate for 

supporting polar bear recovery and conservation, 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 primarily, 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 conservation 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 priorities. Therefore, estimated costs to full recovery are 

shown by projecting forward in five-year increments 

each of the costs included, with appropriate adjustments 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 aggressive 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 warming 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 Protection 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 aggressive 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 partners 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 undertaking 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, respectively. 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 consistent 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 Circumpolar 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 humanbear 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 recognizes 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 partnerships 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 overarching 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 management (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 location 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 distribution 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 management 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 removals 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 management and conservation actions are tied to preestablished 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 relatively 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 removals, 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 behavior 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 probability 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, defenseof-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 appropriate 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 participating 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 framework 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 consumption 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 provided in Appendix B. The monitoring actions identified 

at this time are those possible with available knowledge 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 Universities, 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 document. 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 demographic 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 monitoring these criteria, which describe the condition of 

polar bears and their environment, it is also important 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 framework necessary to meet the goals of this Plan. 

This section outlines methods to monitor demographic 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 implementing 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 Knowledge, 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 removals in the SB subpopulation Number of direct, lethal removals in the SB Monitor the number of defense-of-life removals in subpopulation the SB subpopulation from villages, industry, and 

any other causes

Monitor the number of subsistence hunting removals in the CS subpopulation Number of direct, lethal removals in the CS Monitor the number of defense-of-life removals in subpopulation 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 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%.

4. Total direct human-caused removals in each 

recovery unit do not exceed a rate h (relative to 

the subpopulation size) that maintains the population 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 humancaused 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 km2) 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 subpopulation

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., rmnpl, 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 nutritional 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.1

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.

1 The level of human-caused removal is needed to calculate 

the effect of those removals on persistence, but collecting 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 humancaused 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 interactions 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 interactions. 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 envision 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 monitoring 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 persistencebased 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 demographics. 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 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.

Human-polar bear conflict. There is a need to 

continuously improve our understanding of humanpolar 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 essential 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 information 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 subpopulations 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 humancaused 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 reproduction 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 populations 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 identifiable 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 otherwise 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 significant portion of its range” (16 USC 1532(20)). Polar bears 

were classified as threatened under the ESA in 2008.

Traditional ecological knowledge (TEK). The cumulative 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 Agreement) and the Southern Beaufort Sea (SB) subpopulation. 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, paddlelike 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 condition 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 reproductive 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 populations (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 population 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 21st 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-ofthe-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 subpopulation 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 Council 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 radiotracking 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 recognized 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 declining (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 subpopulation 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 Southern Beaufort Sea subpopulation had an estimated 

population size of approximately 900 bears in 2010 

(Bromaghin et al. 2015). This represents a significant reduction from previous estimates of approximately 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 distribution 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). Shorefast 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 maintenance (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 successfully 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 riverbanks 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 annually and the northeastern coast of the Chukotka 

Peninsula, Russia (Stishov 1991; Ovsyanikov 2005; 

Obbard et al. 2010). 

Threats Assessment/Reasons for Listing 

under the ESA1

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. 

1 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 throughout 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 greenhouse 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 subpopulations 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 addition 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 strategies (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) demonstrated 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 regionally. Recent studies indicate that polar bear movements 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 aggregations 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 subsistence activities. 

Seasonal polar bear distribution changes, the negative 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 (Stirling and Øritsland 1995; Stirling 2002). Ringed seal 

populations are known to exhibit natural fluctuations, but there is concern that longer-term population 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 9th 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 predation 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 snowcovered 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 resting 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), TRAFFIC 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 activities (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 populations (Regehr et al. 2015). 

Since 2008, concerns persist about subsistence 

harvest levels for several subpopulations, particularly 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 humancaused 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 population 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 sustainable 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 scientific 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 differently 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 objectives: (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. Management 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 recognized 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 hunting 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 estimated 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 projections 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-oflife removals from the SB subpopulation by nonAlaska 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 cubsof-the year have been removed from their natural 

environment since 2008. In 2011, one orphaned 

female cub from the SB subpopulation was recovered 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, shipping, 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 activities 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 immunocompromised/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 Derocher 2007), there is no indication that these stressors 

have resulted in population level effects.

C. 4. Interspecific competition

One form of interspecific competition is crossbreeding, 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 subpopulations. 

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 physiological effects of these interactions on individual polar 

bears are not fully determined. 

D. Inadequacy of existing regulatory mechanisms

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 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 (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/negotiations/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 contaminant concentrations were not thought to have 

population level effects on most polar bear populations, 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 hexachlorocyclohexanes (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, chlorinated 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 reproductive 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 producing 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 Department 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 occurring 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 considered 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 decisionmaking 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 affecting 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 Northeast 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 environment (AMSA 2009). The AMSA Report includes a 

comprehensive estimate of how many ships (excluding 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 environmental 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 Organization (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 ecological 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 environmental 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 January 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 agencies, 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 conservation and management of polar bear subpopulations 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 population. 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 communities 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 organizations in order to carry out agreements made 

under the section. 

The MMPA Incidental and Intentional Take 

Program (IITP) allows for the incidental nonintentional 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 Deterrence 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 agreements 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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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, biosampling 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 persistencebased 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 offshore 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 technical 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 population dynamics is the discrete logistic model, which 

describes the trajectory of a population using the 

formula,

NNNNtttt+1 = NNNNtttt + rrrrNNNNtttt �1 − NNNNtttt

KKKK � − hNNNNtttt (C1)

where Nt 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

NNNNeeeeeeee = KKKK �1 − h

rrrr

� (C2)

that allows a sustained annual removal (annual 

harvest) of a number of individuals as calculated by 

the formula:

HHHHeeeeeeee = hNNNNeeeeeeee = hKKKK �1 − h

rrrr

� = hKKKK − h2 KKKK

rrrr . (C3)

Plotting Heq against Neq 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 combinations of Neq and Heq: when h = 0, Neq = K and 

the annual harvest is, of course, 0. As h increases, 

Neq decreases and Heq increases until a maximum 

sustainable annual harvest is reached. (For the 

discrete logistic model, this maximum occurs at h = 

r/2, Neq = K/2, and Heq = rK/4.) The harvest rate 

can continue to increase, pushing the equilibrium 

point over to the left side of the yield curve; now Neq

continues to decrease, but so does Heq. When h ≥ r, 

Neq = 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

0 K

Annual Harvest (

H)

Population Size (N)

h

Neq

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 Neq, 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 Neq; if the population size is greater 

than Neq, the annual harvest (on the black line) will 

exceed the surplus production, and the population 

will decrease back toward Neq. The stability of the 

equilibrium point is the reason that using a sustainable, 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 deterministic, it can also serve as the central tendency of a 

stochastic model, and under reasonable assumptions 

about the nature of the annual variation, the fixedrate 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 harvestable 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,

NNNNtttt+1 = φφφφNNNNtttt(1 + RRRRtttt) − hNNNNtttt (C4)

where φ is the survival rate and R is the recruitment 

rate (the number of offspring produced per adult). 

Let’s assume that the survival rate, φ, 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

RRRRtttt = aaaa + bbbbNNNNtttt (C5)

where a is the reproductive rate at very low densities (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,

NNNNtttt+1 = φφφφNNNNtttt(1 + aaaa + bbbbNNNNtttt) − hNNNNtttt =

φφφφ(1 + aaaa)NNNNtttt + φφφφbbbbNNNNtttt

2 − hNNNNtttt (C6)

Now, by comparing eq. C6 to eq. C1 and making the 

following substitutions, 

φφφφ(1 + aaaa) = 1 + rrrr, and φφφφbbbb = −rrrr⁄KKKK (C7)

we calculate

NNNNtttt+1 = (1 + rrrr)NNNNtttt − rrrrNNNNtttt

2

KKKK − hNNNNtttt =

NNNNtttt + rrrrNNNNtttt �1 − NNNNtttt

KKKK � − hNNNNtttt

(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 parameters of the discrete logistic (r and K) in terms of the 

parameters in the density-dependent formulation (a, 

b, and φ),

rrrr = φφφφ(1 + aaaa) − 1

KKKK = 1 − φφφφ(1 + aaaa)

φφφφbbbb (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 reproductive rate decreases. When the reproductive rate 

matches the mortality rate, there is a stable equilibrium point (K0). 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 (K1).

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 equilibrium point at which reproduction offsets mortality 

decreases (K1).

Although the effect of these two types of environmental 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

0 K1 K0

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 experience 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 K0 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 population size is stable (K0). Changes in the environment that affect 

the reproductive rate (here we assume a negative effect) can 

shift the carrying capacity to a new level (K1), 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 K1 K0

Demographic Rate

Population Size

0.0

0.1

0.2

0.3

0.4

0 K1 K0

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 K1 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 humancaused removals do not exceed a rate h (relative to 

the subpopulation size) that maintains the subpopulation 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 statedependent 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 constraints1, take can continue but absolute 

take levels would decline. For example, at a fixed 

removal rate of 4.5% (Taylor et al. 1987), subpopulation 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.

1 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 extensively 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 θ-logistic model, 

described by

NNNNtttt+1 = NNNNtttt + rrrrNNNNtttt �1 − �

NNNNtttt

KKKK �

θθθθ

� − hNNNNtttt (C10)

where the parameter θ controls the non-linearity in 

the dynamics. The population size that produces the 

greatest net productivity (annual harvest) is

NNNNeeeeeeee

∗ = mmmmmmmmmmmmmmmm = KKKK � 1

1 + θθθθ

�

1/θθθθ

, (C11)

which occurs when the harvest rate is

hmmmmmmmmmmmmmmmm = θθθθrrrr

1 + θθθθ . (C12)
Polar Bear Conservation Management Plan 101

Appendix C—Population Dynamics and Harvest Management

Thus, the effect of an increasing θ 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

0 K

Annual Harvest

Population Size

θ = 2

θ = 1

θ = 3

θ = 5

Figure C-4. Yield curves for a θ-logistic population model. The 

four curves share the same carrying capacity (K) and intrinsic 

rate of growth (r), but differ in the θ 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 θ-logistic model, but the 

yield curve is roughly approximated by a θ-logistic 

model with r = 0.07 and θ = 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 Demographic 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, hmnpl, 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 hmnpl 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 management 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 removals, 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 conditions 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 environment 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 population 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 mechanisms 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 corresponding 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 humancaused 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 possibility 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 removals 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 dynamics. 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.

0

0 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

0

0 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 corresponding 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 capacity. The graphs were derived using a theta-logistic population 

model with θ = 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 Ecology.

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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