Kane Basin (KB)

A new estimate of 357 bears shows the subpopulation are likely increasing.

Status table outtake

Size Sea ice metrics Human-caused removals 2010–2014
Estimate /
95% CI
Year Method Change in spring ice retreat / Change in fall ice advance (days per decade) Change in summer sea ice area (percent change per decade) 5-yr mean Last year
Potential Actual Potential Actual
357
221-493
2013-2014Genetic capture-recapture-7.2/5.6-12.2115115
See also the complete table (all subpopulations)

Comments, vulnerabilities and concerns

More bears were documented in the eastern regions of the KB subpopulation area during 2012 – 2014 than during 1990s surveys which may reflect differences in spatial distribution of bears, possibly influenced by reduced hunting pressure by Greenland in eastern KB, but also some differences in sampling protocols between decades. Some caution should be taken in the interpretation of population growth. An additional estimate of abundance based on a springtime 2014 aerial survey in KB was 206 bears (95% lognormal CI: 83 - 510).

Status and delineation

Kane Basin subpopulation mapThe Kane Basin area. See also the complete map (all subpopulations).

Based on the movements of adult females with satellite collars and recaptures of tagged animals, the boundaries of the Kane Basin subpopulation include the North Water Polynya to the south, the Kennedy Channel to the north and Greenland and Ellesmere Island to the east and west (Taylor et al. 2001). Polar bears in KB do not differ genetically from those in Baffin Bay (Paetkau et al. 1999; Peacock et al. 2015). The size of the subpopulation was estimated to be 164 ± 35 (SE) for 1994 – 1997 by Taylor et al. (2008). The intrinsic natural rate of growth for KB polar bears was estimated to be low at 1.009 (SE, 0.010) (Taylor et al. 2008), likely because of large expanses of multi-year ice and low population density of seals (Born et al. 2004). A genetic mark-recapture survey (via biopsy darting) and aerial survey were completed in 2014 resulting in a new population estimate, survival rates, and habitat use analyses (SWG 2016). Using genetic mark-recapture, the estimated abundance of the KB subpopulation was 357 polar bears (95% CI: 221 – 493) for 2013 – 2014. More bears were documented in the eastern regions of the KB subpopulation during 2012 – 2014 than during 1994-1997.The difference in distribution between the 1990s and 2010s may reflect differences in spatial distribution of bears, possibly influenced by reduced hunting pressure by Greenland in eastern KB but also some differences in sampling protocols. An estimate of abundance based on a springtime 2014 aerial survey in KB was 206 bears (95% lognormal CI: 83 - 510).  However, due to insufficient coverage of offshore polar bear habitat, this estimate is likely negatively biased. The total number of bears marked during studies in 2012-2013 in KB was equivalent to ~25% of the estimated population size.  Despite this, documented cases of emigration comprised < 4% of recaptures and recoveries in KB.

Changing sea-ice conditions have resulted in broad movement and habitat use patterns of KB bears that are more similar to those of bears in seasonal sea-ice ecoregions. The size of the subpopulation range has expanded since the 1990s in all seasons, especially in summer (June-September) where ranges doubled between the 1990s and the 2000s. Land use in KB during summer remains intermittent because some sea ice remains inside fjords and coastal areas. Reproductive metrics for KB were comparable between the 1990s and 2010s sampling periods. Body condition in KB appeared to have slightly improved between sampling periods (see SWG 2016).  Overall, the data on abundance when considered with data on movements, condition, and reproduction, suggest evidence that the subpopulation has increased.

References

Born, E.W., Teilmann, J., Acquarone, M. and Rigét, F. F. 2004. Habitat use of ringed seals (Phoca hispida) in the North Water area (North Baffin Bay). Arctic 57:129–142.

Canadian Wildlife Service. 2009. Nunavut consultation report – Consultations on the proposed listing of the Polar Bear as Special Concern under the Species at Risk Act. Report submitted to the Nunavut Wildlife Management Board in accordance with Step 3.8 of the Memorandum of Understanding to Harmonize the Designation of Endangered Species under the Nunavut Land Claims Agreement and the Species at Risk Act, 249 pp. [available at: http://assembly.nu.ca/library/Edocs/2009/001149-e.pdf].

Paetkau, D., Amstrup, S.C., Born, E.W., Calvert, W., Derocher, A.E., Garner, G.W., Messier, F., Stirling, I., Taylor, M.K., Wiig, Ø., and Strobeck, C. 1999. Genetic structure of the world's polar bear populations. Molecular Ecology 8: 1571–1584.

Peacock, E., Sonsthagen, S.A., Obbard, M.E., Boltunov, A., Regehr, E.V., Ovsyanikov, N., Aars, J., Atkinson, S.N., Sage, G.K., Hope, A.G., Zeyl, E., Bachmann, L., Ehrich, D., Scribner, K.T., Amstrup, S.C., Belikov, S., Born, E., Derocher, A.E., Stirling, I., Taylor, M.K., Wiig, Ø., Paetkau, D., and Talbot, S.L. 2015. Implications of the circumpolar genetic structure of polar bears for their conservation in a rapidly warming Arctic. Plos One 10: e112021.

SWG [Scientific Working Group to the Canada-Greenland Joint Commission on Polar Bear]. 2016. Re-Assessment of the Baffin Bay and Kane Basin Polar Bear Subpopulations: Final Report to the Canada-Greenland Joint Commission on Polar Bear. 31 July 2016: x + 636 pp.

Taylor, M.K., Akeeagok, S., Andriashek, D., Barbour, W., Born, E.W., Calvert, W., Dean Cluff, H., Ferguson, S., Laake, J. Rosing-Asvid, A., Stirling, I., and Messier, F. 2001. Delineating Canadian and Greenland polar bear (Ursus maritimus) populations by cluster analysis of movements. Can. J. Zool. 79: 690–709.

Taylor, M.K., Laake, J., McLoughlin, P.D., Cluff, H.D., Born, E.W., Rosing-Asvid, A., and Messier, F. 2008. Population parameters and harvest risks for polar bears (Ursus maritimus) of Kane Basin, Canada and Greenland. Polar Biology 31: 491–499.