This indicator tracks changes in the top predator in the Arctic, the polar bear. The indicator gives information on polar bear sub-population trends in the management areas found, at least partly, in the NWT: the Southern Beaufort Sea (SB), the Northern Beaufort Sea (NB) and the Viscount Melville Sound (VM).The indicator links these trends to habitat changes in these areas. A few bears from the Arctic Basin management area may also move to the NWT, but they are not included in this indicator.
As a top predator, polar bear is an excellent indicator of the overall change in their Arctic habitat including multi-year sea ice used by some bears for denning and prey availability.
The indicator is compiled by ENR using information from COSEWIC1, SARC2 and the IUCN/SSC Polar Bear Specialist Group. Data and analyses were obtained from studies by ENR, Environment Canada and the US Geological Survey. Sea ice trends are from the Canadian Ice Service3.
About 50% of polar bear populations are found in Canada and about 10% are in the NWT. In 2008, polar bear was re-assessed as a species of special concern by COSEWIC1.
Polar bear management is guided by the US/Canada MOU on Conservation and Management of Shared Polar Bear Populations. Trade in polar bear parts is guided by Appendix II of the Convention on the International Trade in Endangered Species (CITES).
Current view: status and trend
Analyses of population declines and hunting pressure are done for each management area separately (by sub-populations), but there is evidence polar bears in the NWT travel long distances. There is interchange between the Northern and Southern Beaufort Sea management areas1,2.
Polar bears in the NWT feed almost exclusively on ringed seals, although bearded seals are also hunted4. Polar bears in the Beaufort Sea use multi-year ice and land to den. Ice is important to bears for traveling and hunting ringed seals. Some bears in the Beaufort Sea never come to land and use ice all year round, moving north in summer and south again in winter. In the U.S. portion of the southern Beaufort Sea, the proportion of dens on the pack ice declined from 62% in 1985-1994 to 37% in 1998-20045. This change in denning behaviour may be related to changes and reductions in sea ice. Increases in problem bear activity have been reported in recent years including in the Southern Beaufort Sea area6.
The Southern Beaufort Sea subpopulation appears to have experienced some decline in population in the recent past and the likelihood of decline in the near future is high (94%). This predicted decline has been attributed to changes in sea ice in the western section of the population’s range along the shore of Alaska (see Big Picture – Sea Ice indicator).
Polar bear populations in the Viscount Melville Sound and Northern Beaufort Sea have been stable or increasing in numbers and are less likely to decline in the near future based on population models, sea ice changes and moderate hunting pressure. Polar bears in the Viscount Melville Sound may actually benefit over the short-term from the changing sea ice. Less multi-year ice may result in increased abundance and accessibility to seals for that population.
|Management Area||Den Habitata||Sub-Population Sizeb||Sub-Population trend - Observedc||Likelihood of Future Population Declined||Sea Ice Trend - Observede||Hunting Pressure Indexf|
|Viscount Melville (VM)||On land||121-201||Uncertain - Increasing?||Not likely||No change or increasing||69%|
|North Beaufort Sea
|Multi-year ice, land||686-1,718||Stable - Increasing||Likely||No change||53%|
|South Beaufort Sea (SB)||Multi-year ice, land||1,210-1,842||Slightly Declining?||Very likely||No change or declining||66%|
a Summary from Thiemann et al. 20087.
b Data summary from SARC20122.. Estimate plus or minus 95% CI. Year of last estimate: VM: 1992 (old, noted in italics), a survey is scheduled in VM for 2012 - results pending; NB: 2006, SB: 2006.
c Analysis follows COSEWIC 20081, based on evidence from population counts between 2006 and the 1980s, except for VM where all counts are from the 1990s, and from simulations to calculate the finite rate of increase, population viability analysis (PVA) including current hunting pressure, and conclusions reached by authors of the primary source listed for each subpopulation. Trend for the NB is supported by TEK study (Paulatuk Oral History)1,2.
d Results of PVA: proportion of simulations resulting in at least 30% future decline after 3 polar bear generations (36 years). VM = 7%; NB=42%; SB=94% chance of future declines.
e Trend from Canadian Ice Service2. See Focal Point 1 The Big Picture – A Changing Planet
f Index according to Thiemann et al. 20087, data summarized from COSEWIC 2008. Index = Number of bears killed on average (2002-2007) divided by the total allowed quota for the sub-population1 * 100. VM: 4.8 harvested/7 quota for NT and NU since 2004-2005; NB: 34.4 harvested /65 quota; SB: 53.4 harvested /81 quota.
- "Some subpopulations shared by Canada and Greenland were until very recently subject to uncontrolled harvests. Of 13 subpopulations, 5 (Western Hudson Bay, Southern Beaufort Sea, Baffin Bay, Kane Basin, and Norwegian Bay), which represent approximately 28% of the total population of 15,500 polar bears shared by Canada and its immediate neighbours (Greenland and Alaska), have a greater than 50% risk of population decline by 30% or more over the next 36 years (3 bear generations). Those projected declines are partly attributable to climate change for Western Hudson Bay and Southern Beaufort Sea, but are mostly due to unsustainable harvest in Kane Basin and Baffin Bay." Quote from COSEWIC 20081.
Abbreviations of management areas are Viscount Melville Sound (VM), Norwegian Bay (NW), Kane Basin (KB), Lancaster Sound (LS), Baffin Bay (BB), Davis Strait (DS) Southern Hudson Bay (SH), Western Hudson Bay (WH), Foxe Basin (FB), Gulf of Boothia (GB), M’Clintock Channel (MC), Southern Beaufort Sea (SB), and Northern Beaufort Sea (NB). Source: IUCN/SSC Polar Bear Specialist Group (2006).
Found an error or have a question? Contact the team at NWTSOER@gov.nt.ca.
Ref 1 - COSEWIC. 2008. Updated COSEWIC status report on the Polar Bear Ursus maritimus in Canada. Ottawa, ON.
Ref 2 - SARC. 2012. Status report on Polar Bear in the NWT. ENR.
Ref 3 - Canadian Ice Service. 2009. Sea Ice Overview, Environment Canada.
Ref 4 - Iverson,S., I.Stirling, S.L.C.Lang. 2006. Spatial and temporal variation in the diets of polar bears across the Canadian Arctic: indicators of changes in prey populations and environment. in Top predators in marine ecosystems. I Boyd,I.L., S.Wanless, and C.J.Camphuysen, Eds. Cambridge University Press, New York, NY, pp. 98-117.
Ref 5 - Fischbach A.S, S.C.Amstrup, and D.C.Douglas. 2007. Landward and eastward shift of Alaskan polar bear denning associated with recent sea ice changes. Polar Biology 30:1395-1405.
Ref 6 - Schliebe S. L., T.J.Evans, S.Miller, C.J.Perham, J.Wilder. 2006. Summary of polar bear management in Alaska 2004/2005. Report to the Canadian Polar Bear Technical Committee.
Ref 7 - Thiemann G.W., Derocher A. E. S. I. 2008. Polar bear Ursus maritimus conservation in Canada: an ecological basis for identifying designatable units. Oryx 42:504-515.