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

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 profile...

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Bibliographic Details
Published in:Polar Research
Main Authors: Jon Aars, Tiago A. Marques, Karen Lone, Magnus Andersen, Øystein Wiig, Ida Marie Bardalen Fløystad, Snorre B. Hagen, Stephen T. Buckland
Format: Article in Journal/Newspaper
Language:English
Published: Norwegian Polar Institute 2017
Subjects:
Ursus maritimus
distance sampling
sea ice
habitat loss
Svalbard
helicopter
Environmental sciences
GE1-350
Oceanography
GC1-1581
Arctic
Barents Sea
Polar Research
Sea ice
Online Access:https://doi.org/10.1080/17518369.2017.1374125
https://doaj.org/article/4db331610f51461f9bd661839232adc9
Description
Summary: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 = 665 – 1884) 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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