Unprecedented Loss of Sea Ice Renews Concerns for Survival of the World’s Polar Bears

IUCN Polar Bear Specialist Group sets eight resolutions for closer management of subpopulations

July 6, 2009 (Copenhagen, Denmark): At the 15th meeting of the IUCN Polar Bear Specialist Group (PBSG), hosted by the Greenland Institute of Natural Resources, the PBSG renewed the conclusion from previous meetings that the greatest challenge to the conservation of polar bears is ecological change in the Arctic, resulting from climatic warming. Declines in the extent of the sea ice have accelerated since the last meeting of the group in 2005, with unprecedented sea ice retreats in 2007 and 2008. Evidence of these environmental changes, in conjunction with a re-evaluation of the polar bear subpopulations, have led PBSG to list eight of 19 subpopulations as currently decreasing, three as stable and one as increasing. For seven, data were insufficient to assign a trend.

“The Western Hudson Bay subpopulation has been on the decline for almost two decades and studies published since the last PBSG meeting in 2005 confirm that body condition in polar bears is linked to the availability of sea ice and time of spring break-up and that when sea ice is available for less time, body condition declines ultimately affecting reproduction in adult female bears. These studies also linked changes in the sea ice to reproductive and survival rates,” said Dr. Erik W. Born, the newly-elected chair of the IUCN Polar Bear Specialist Group.

“Threats to polar bears will occur at different rates and times across their range although warming-induced habitat degradation and loss are already negatively affecting polar bears in some parts of their range. Subpopulations of polar bears are facing different combinations of human threats and the PBSG is recommending that jurisdictions take into account the variation in threats facing polar bears,” added Born.

In addition to shrinking vital sea ice, climate change appears to be altering the pathways by which pollutants enter the polar bears’ ecosystems. Studies show levels of contaminants such as mercury and perfluorinated compounds are high in certain polar bear subpopulations. The PBSG noted exposure to various persistent pollutants have vital endocrine effects on polar bears and is encouraging international efforts to evaluate interactions between climate change and pollutants.

PBSG has put forward resolutions in eight categories to address these threats to polar bears and their habitat, and to better assess the effects on individual subpopulations over the next four years:

• Renewed conclusions of the effects of global warming on the Arctic and polar bears and urgent need for the reduction of greenhouse gas emissions
  
• A continued international study of the effects of pollution on polar bears and the interactions with climate change
  
• Suitable forward actions for Canadian subpopulations based on the 2008 status report on polar bear by the Canadian Committee on the Status of Endangered Wildlife in Canada (COSEWIC)
  
• Minimizing human-polar bear interactions
  
• Recognizing current overharvest, recommends a new population assessment for Baffin Bay
  
• Need for the collection of scientific samples from harvested polar bears in all jurisdictions
  
• Conservation and increased monitoring of the Chukchi Sea polar bear population
  
• Need for polar bear monitoring and capture range wide

The full report on the eight resolutions is available for download.

The PBSG is endorsing efforts to develop non-invasive means of subpopulation assessments, and continues to encourage jurisdictions to incorporate capture and radio tracking programs into their national monitoring efforts. The members also recognize that aboriginal people are both uniquely positioned to observe wildlife and changes in the environment, and their knowledge is essential for effective management.

The PBSG recognizes that where habitats are stable, polar bears are a renewable resource, and reaffirms its support of the right of aboriginal groups to harvest polar bears within sustainable limits. But the PBSG notes that the population of polar bears in Baffin Bay, shared by Greenland and Canada, may simultaneously be suffering from significant habitat change and substantial over harvest, while at the same time interpretations by scientists and local hunters disagree regarding population status. Similarly, the Chukchi Sea polar bear population, which is shared by Russia and the United States, is likely declining due to illegal harvest in Russia and one of the highest rates of sea ice loss in the Arctic. Consistent with its past efforts to coordinate research and management among jurisdictions, the PBSG is recommending that the polar bear populations in Baffin Bay and the Chukchi Sea be reassessed and that harvests be brought into balance with the current sustainable yield.

“We are very pleased to see that some jurisdictions have implemented positive management changes based on our recommendations from the 2005 PBSG meeting. Quotas for the harvest of polar bears in Greenland were put in place in January 2006, and there have even been quota reductions in some parts of Greenland. The government of Nunavut has also recently reduced the harvest quota in Western Hudson’s Bay because of the documented population decline,” said Born.

The PBSG re-evaluated the status of the 19 recognized subpopulations of polar bears distributed over vast and relatively inaccessible areas of the Arctic. Despite the fact that some new information has been made available since the last meeting, total knowledge of some populations is still poor. This is a matter of funding availability.  For example, there are no population studies in Russia and there never have been studies there that would allow quantitative population assessment.  In Canada, home to two thirds of the world's polar bears, many subpopulations have been assessed, but for some it has been so long ago that PBSG could not be confident that those old findings apply today.  Some populations in Canada have good estimates of size, but no comparative data with which to assess a trend in size.  

Reviewing the latest information available, the PBSG concluded that one of 19 subpopulations is currently increasing, three are stable and eight are declining. For the remaining seven subpopulations, available data were insufficient to provide an assessment of current trend.

The subpopulation increasing is located in Canada’s high Arctic, an area that has not seen as much loss of sea ice as others, supporting the Group’s analysis of the critical relationship between the health of polar bears and the amount of sea ice.

Other subpopulations that had previously been increasing have now been identified as on the decline or ‘data deficient’. PBSG noted that in the past, some populations had been critically low due to over-harvesting. More recently, harvests were dramatically reduced with a goal of allowing them to rebuild in numbers, and it was assumed that they must be increasing from those low numbers.  However, at this meeting some of those populations were put into the data deficient column because PBSG is no longer confident they are increasing given the long time span since any real data was made available.

The Davis Strait subpopulation illustrates the difficulty in interpreting the worldwide trend. PBSG had listed numbers in this area higher than previously estimated, however, the reproductive and survival rates, along with the population size and mathematical projections, indicate the population has likely peaked and has started to turn downward. So here is a population that may be at all time high numbers but has moved into the declining category.  

The total number of polar bears is still thought to be between 20,000 and 25,000. However, the mixed quality of information on the different subpopulations means there is much room for error in establishing that range. That potential for error, given the ongoing and projected changes in habitats and other potential stressors is cause for concern. Nonetheless, the PBSG is optimistic that humans can mitigate the effects of global warming and other threats to polar bears, and ensure that they remain a part of the Arctic ecosystem in perpetuity.

The IUCN (International Union for the Conservation of Nature and Natural Resources) Polar Bear Specialist Group is composed of researchers and managers representing each of the five circumpolar nations that signed the International Agreement for the Conservation of Polar Bears of 1973 – Canada, USA, Greenland (Denmark), Norway and Russia. Since the late 1960’s, the members of PBSG have met every three to five years under the umbrella of the Species Survival Commission of the IUCN to review and exchange information and make recommendations for research and management of polar bears throughout the Arctic.

Current Trends of 19 Subpopulations

East Greenland
Data deficient

Barents Sea
Data deficient

Kara Sea
Data deficient

Laptev Sea
Data deficient

Chukchi Sea
Declining

Southern Beaufort Sea
Declining

Northern Beaufort Sea
Stable

Viscount Melville
Data deficient

Norwegian Bay
Declining

*Lancaster Sound
Declining

M'Clintock Channel
Increasing

Gulf of Boothia
Stable

Foxe Basin
Data deficient

Western Hudson Bay
Declining

Southern Hudson Bay
Stable

Kane Basin
Declining

Baffin Bay
Declining

Davis Strait
Declining

Arctic Basin
Data deficient