The number and distribution of polar bears in the western Barents Sea

  • Jon Aars Norwegian Polar Institute, Fram Centre, Tromsø
  • Tiago A. Marques Centre for Research into Ecological and Environmental Modelling, University of St Andrews, St Andrews, Scotland, United Kingdom, and Faculdade de Ciências da Universidade de Lisboa, Centro de Estatística e Aplicações da Universidade de Lisboa, Lisboa, Portugal
  • Karen Lone Norwegian Polar Institute, Fram Centre, Tromsø
  • Magnus Andersen Norwegian Polar Institute, Fram Centre, Tromsø
  • Øystein Wiig Natural History Museum, University of Oslo
  • Ida Marie Bardalen Fløystad Norwegian Institute of Bioeconomy Research, Svanvik
  • Snorre B. Hagen Norwegian Institute of Bioeconomy Research, Svanvik
  • Stephen T. Buckland Centre for Research into Ecological and Environmental Modelling, University of St Andrews, St Andrews, Scotland, UK
Keywords: Ursus maritimus; distance sampling; sea ice; habitat loss; Svalbard; helicopter

Abstract

Polar bears have experienced a rapid loss of sea-ice habitat in the Barents Sea. Monitoring this subpopulation focuses on the effects on polar bear demography. In August 2015, we conducted a survey in the Norwegian Arctic to estimate polar bear numbers and reveal population substructure. DNA profiles from biopsy samples and ear tags identified on photographs revealed that about half of the bears in Svalbard, compared to only 4.5% in the pack ice north of the archipelago, were recognized recaptures. The recaptured bears had originally been marked in Svalbard, mostly in spring. The existence of a local Svalbard stock, and another ecotype of bears using the pack ice in autumn with low likelihood of visiting Svalbard, support separate population size estimation for the two areas. Mainly by aerial survey line transect distance sampling methods, we estimated that 264 (95% CI = 199 – 363) bears were in Svalbard, close to 241 bears estimated for August 2004. The pack ice area had an estimated 709 bears (95% CI = 334 – 1026). The pack ice and the total (Svalbard + pack ice, 973 bears, 95% CI = 334 – 1026) both had higher estimates compared to August 2004 (444 and 685 bears, respectively), but the increase was not significant. There is no evidence that the fast reduction of sea-ice habitat in the area has yet led to a reduction in population size. The carrying capacity is likely reduced significantly, but recovery from earlier depletion up to 1973 may still be ongoing.

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Published
2017-10-09
How to Cite
Aars, J., Marques, T., Lone, K., Andersen, M., Wiig, Øystein, Bardalen Fløystad, I. M., Hagen, S., & Buckland, S. (2017). The number and distribution of polar bears in the western Barents Sea. Polar Research, 36. Retrieved from https://polarresearch.net/index.php/polar/article/view/2660
Section
Research Articles