The global status of polar bear subpopulations

IUCN/SSC Polar Bear Specialist Group

Prepared by: Kristin Laidre, Dag Vongraven,

Geoff York and Jim Wilder

Polar Bear Range States Meeting of the Parties, Ilulissat, Greenland, 1-3 September 2015

• PBSG Terms of Reference

• PBSG Status Table components

• Global status of subpopulations

• Sea ice metric

• Variability and uncertainty

• Recent peer-reviewed research

• Redlist assessment status

Outline

“To coordinate, synthesize and distribute scientific information necessary to guide the long-term viability of

polar bears and their habitats.”

PBSG Mission

PBSG Terms of Reference, 2012

2014 PBSG Status Table

19 subpopulations

Estimated 20,000-25,000 polar bears

throughout the range

Current Global Trend 2014

19 subpopulations9 unknown3 declining

6 stable1 increasing

PBSG Status Table, 2014

Declining subpopulations (n=3)

Subpopulation

Subpopulation size

Human-caused removals: 2010-2014

References

5-year mean Last year

Estimate 95% CI Year Method Potential Actual Potential ActualBaffin Bay

1546690-2402 2004

PVA (based on physical capture-

recapture estimate from 1998) 144 149 132 137

Taylor et al. 2005; Rode et al. 2012; Peacock et al. 2012.

Kane Basin 164 94-234 1994-1997 Physical capture-recapture

11 6 11 5 Taylor et al. (2008); Canadian Wildlife Service Nunavut Consultation Report 2009.

Southern Beaufort Sea

907 548-1270

2010 Capture-recapture 76 35.6 73 42.3 Hunter et al. (2010), Bromaghin et al. (2015)

Stable subpopulations (n=6)

Subpopulation

Subpopulation size

Human-caused removals: 2010-2014

References

5-year mean Last year

Estimate 95% CI Year Method Potential Actual Potential Actual

Davis Strait 2158 1833-2542 2007 Physical capture-recapture

99 99 103 105 Peacock et al. (2013)

Foxe Basin 2580 2093-3180 2009/10 Distance sampling 97.8 104 71 85 Stapleton et al. (2012); Sahanatian and Derocher (2012)

Gulf of Boothia 1592 870-2314 2000 Physical C-R 60 58 58 52 Taylor et al. (2009); Barber and Iacozza (2004)

Northern Beaufort Sea

980 825-1135 2006 Physical capture-recapture

65 37.4 65 43 Stirling et al. (2011); Stirling et al. (1988)

Southern Hudson Bay

951 662-1366 2012 Distance sampling 60 62 60 56 Obbard et al. (2013)

Western Hudson Bay

1030 754-1406 2011 Distance sampling 22.6 23.2 28 32 Stirling et al. (1999), Derocher et al. (2004), Regehr et al. (2007), Molnár et al. (2010, 2011), Lunn et al.

(2014), Stapleton et al. (2014)

Increasing subpopulations (n=1)

Subpopulation

Subpopulation size

Human-caused removals: 2010-2014

References

5-year mean Last year

Estimate 95% CI Year Method Potential Actual Potential ActualM'Clintock Channel

284 166-402

2000 Physical C-R 3 3 3 3Taylor et al. (2006); Barber and Iacozza (2004)

Subpopulations with unknown status (n=5)

Subpopulation

Subpopulation size

Human-caused removals: 2010-2014

References

5-year mean Last year

Estimate 95% CI Year Method Potential Actual Potential ActualArctic Basin Unknown

Chukchi Sea Unknown 58 30 (U.S.) + approx. 32

(Russia)

58 23 (U.S.) + approx. 32

(Russia)

Belikov (1993); Ovsyanikov(2012); Rode et al. (2014); Kochnev and Zdor (2014)

East Greenland Unknown 62 63 64 65

Kara Sea Unknown NA NA

Lancaster Sound 2541 1759-3323 1995-1997 Physical C-R 93 84.8 102 83

Laptev Sea Unknown NA NA

Norwegian Bay 203 115-291 1997 Physical C-R 4 2.2 4 3 Taylor et al. (2008); Canadian Wildlife Service Nunavut

Consultation Report 2009.Viscount Melville

Sound161 121-201 1992 Physical capture-

recapture5.6 7.0 6.0 7.0 Taylor et al. (2002); Messier et al.

(1992); Messier et al. (1994)

Population status history

2014 PBSG Status Table

Sea ice is the primary habitat for polar bears

Travel Hunt

Mate Some maternity denning

Warming in the Arctic over the past few decades has been about two times greater than the global mean

Observations and climate models indicate we are on track for a nearly ice-free Arctic in summer by 2040

Declines expected to continue for 25+ years regardless of limits in GHGs

Means fundamental changes for polar bears and humans that rely on them as resources

(Stroeve et al. 2012, Overland & Wang 2013, IPCC 2013)

Primary long-term threat to polar bears is loss of sea ice

Adapted by USGS from Figure SPM.7b of the 2013 IPCC Working Group I, Summary for Policymakers

PBSG sea ice metric

Dates of fall sea-ice advance

Duration of low sea-ice season

Dates of spring sea-ice retreat

1

•A standardized metric of habitat change has been lacking

•To address this we developed two sea ice metrics

•Used in PBSG Status Table and 2015 Red List Assessment

1

2 3

50%

Trend towards longer summer season, 1979-2014

PBSG 2014 Status Table; Stern and Laidre (In review)

Variability and uncertainty

There is variability in the current status of polar bear subpopulations based on the best-available scientific information.

There is also uncertainty in the scientific information, especially concerning unstudied and less-studied subpopulations.

Over the near and mid-term, there is likely to continue to be variability in sea ice loss impacts on polar bears. However, nearly all subpopulations are expected to be negatively impacted by sea ice loss in the long-term.

Peer-reviewed research on polar bears

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From the Web of Science

Peer-reviewed research since Moscow 2013

110 papers from the Web of Science

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Laidre et al. 2015:Status of Arctic marine mammal populations

Circumpolar trends for 78 Arctic marine mammal subpopulations

Increase, Stable, Decline, Unknown

Recommendations for effective conservation of Arctic marine mammals:

1. Maintain and improve co-management by local, federal, and international partners;

2. recognize spatial and temporal variability in AMM subpopulation response to climate change;

3. implement monitoring programs with clear goals;4. mitigate cumulative impacts of increased human

activity; 5. and recognize the limits of current protected species

legislation.

Laidre et al. 2015:Status of Arctic marine mammal populations

Atwood et al. 2015: Relative influence of population stressors

Objective:Identify which known and suspected stressors are likely to have the greatest influence on population outcomes

Approach:Update the 1st generation Bayesian network polar bear model to evaluate how different management scenarios may influence future population outcomes

• Ecoregions = units of analysis• Project population outcomes using 2

scenarios of future greenhouse gas emissions• Unabated• Stabilized (by midcentury)

Key findings:• Outcomes worsen under both

stabilized and unabated emissions pathways.

• Stabilization buys some time (i.e., delays some bad outcomes by ~25 years).

• Sea ice and prey availability remain the most influential drivers of outcomes.

• Mitigating stressors other than sea ice and prey availability may slow, but won’t prevent, the transition to worsened outcomes.

Atwood et al. 2015: Relative influence of population stressors

In 2015, the U.S. Fish and Wildlife Service and partners developed a new demographic model for polar bears to:

Evaluate the effects of human-caused removals

Better understand population dynamics

Inform conservation planning (e.g., used in the U.S. National Action Plan)

The model is a population viability analysis framework with several key components:

Matrix-based population model to represent the polar bear life cycle

Ability to consider how variation and trends in carrying capacity affect population dynamics

Density-dependent functions based on individual energetic requirements, population dynamics theory, and polar bear biology

Regehr et al. (2015) available at: http://pubs.usgs.gov/of/2015/1029/

Regehr et al. 2015:A demographic model to inform conservation planning

The model can be used to estimate harvest rates that (1) maintain a target population size with respect to carrying capacity, and (2) have a low risk of causing an unacceptable population decline

Harvest rates are evaluated as a function of several factors:

Current data on subpopulation status

Current and future habitat change

Quality of data and time lags in management (e.g., better data lead to informed management decisions, which can reduce risk)

Composition of harvested animals (e.g., young males vs. adult females)

Risk tolerance (e.g., more risk may be acceptable if a subpopulation is over-abundant, less if it is declining or vulnerable)

Regehr et al. 2015:How can this inform management of human-caused removals?

This work suggests that the historic 4.5% harvest rate, at a 2:1 male-to-female ratio, is reasonable under many conditions, although lower or higher rates may be appropriate

It also suggests that harvest is unlikely to accelerate population declines caused by declining carrying capacity, provided that several conditions are met:

The harvest rate reflects current population status, noting that this rate could be zero under some conditions

The harvest level is obtained by applying the identified rate to an estimate of subpopulation size

The harvest rate reflects data quality (i.e., poor data → lower harvest)

Human-caused removals are monitored and can be adjusted

Additional reductions are implemented if the population size falls below a specified threshold

from Regehr et al. 2015

Regehr et al. 2015:A demographic model to inform conservation planning

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Future global status of polar bears

2008 Red List Assessment (based on expert opinion): “Vulnerable” (Schliebe et al. 2008)

Red List Assessment update:

• Includes estimation of generation length based on field data from all studied polar bear subpopulations (n=11)

• Incorporates a standardized sea ice metric• Uses a quantitative approach to evaluate relationships between

population status and sea ice• Recently having undergone external, non-PBSG, non-IUCN review• Submitted to IUCN for official review Friday Aug 28• Planned release in November 2015

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Thank you for your attention

PBSG Delegation members:Dag Vongraven, Norwegian Polar Institute (chair) – vongraven@npolar.noGeoff York, Polar Bears InternationalJim Wilder, National Forest Service, ex-USFWS

Additional members:Jon AarsSteve AmstrupTodd AtwoodStanislav BelikovAndrei BoltunovAndrew DerocherRune DietzGeorge DurnerMarkus Dyck

Morten EkkerAmalie JessenAnatoly KochnevKristin LaidreNick LunnMarty ObbardNikita OvsyanikovElizabeth Peacock

Eric RegehrEvan RichardsonKaryn RodeChristian SonneIan StirlingGreg ThiemannFernando UgarteØystein Wiig