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ESR 51:73-87 (2023)  -  DOI:

Demographic response of a high-Arctic polar bear (Ursus maritimus) subpopulation to changes in sea ice and subsistence harvest

Kristin L. Laidre1,2,*, Todd W. Arnold3, Eric V. Regehr1, Stephen N. Atkinson4, Erik W. Born2, Øystein Wiig5, Nicholas J. Lunn6, Markus Dyck4,†, Harry L. Stern1, Seth Stapleton3, Benjamin Cohen1, David Paetkau7

1Applied Physics Laboratory, Polar Science Center, University of Washington, Seattle, WA 98105, USA
2Greenland Institute of Natural Resources, PO Box 570, 3900 Nuuk, Greenland
3Department of Fisheries, Wildlife, and Conservation Biology, University of Minnesota, St. Paul, MN 55108, USA
4Wildlife Research Section, Department of Environment, Government of Nunavut, Igloolik, NU X0A 0L0, Canada
5Natural History Museum, PO Box 1172 Blindern, 0318 Oslo, Norway
6Environment and Climate Change Canada, CW-422 Biological Sciences Building, University of Alberta, Edmonton, AB T6G 2E9, Canada
7Wildlife Genetics International, Nelson, BC V1L 5P9, Canada
*Corresponding author:

ABSTRACT: Climate change is a long-term threat to polar bears. However, sea-ice loss is hypothesized to provide transient benefits in high latitudes, where thick multiyear ice historically limited biological productivity and seal abundance. We used joint live-recapture and dead-recovery mark-recapture models to analyze data for one of the most northerly polar bear subpopulations, Kane Basin. The data consisted of 277 initial live captures and genetic identifications (1992-1997 = 150, 2012-2014 = 127), 89 recaptures or re-identifications (1992-1997 = 53, 2012-2014 = 36), and 24 harvest returns of research-marked bears during 1992-2014. We estimated mean annual abundance of 357 bears (95% CI: 221-493) for 2013-2014. This suggests a likely increase relative to our estimate of 224 (95% CI: 145-303) bears in the mid-1990s and relative to a previously published estimate of 164 (95% CI: 94-234) bears in the mid-1990s that used some of the same data. This is also supported by an apparent increase in the density of bears in eastern Kane Basin during 2012-2014. Estimates of total survival for females ≥3 yr old (mean ± SE: 0.95 ± 0.04) and their dependent offspring were similar to previous estimates from the 1990s, and estimates of unharvested survival for females ≥3 yr (0.96 ± 0.04) appear sufficient for positive population growth. Estimates of total survival were lower for males ≥3 yr (0.87 ± 0.06). We documented a reduction in mortality associated with subsistence harvest, likely attributable to implementation of a harvest quota by Greenland in 2006. Our findings, together with evidence for increased range sizes, improved body condition for all sex and age classes, and stable reproductive metrics, show that this small high-Arctic polar bear subpopulation remains productive and healthy. These benefits are likely temporary given predictions for continued climate change.

KEY WORDS: Genetic mark-recapture-recovery · Polar bear · Kane Basin · Abundance · Sea ice · Ursus maritimus

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Cite this article as: Laidre KL, Arnold TW, Regehr EV, Atkinson SN and others (2023) Demographic response of a high-Arctic polar bear (Ursus maritimus) subpopulation to changes in sea ice and subsistence harvest. Endang Species Res 51:73-87.

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