Polar bears: the conservation of an arctic icon in a warming climate

Abstract

Subpopulation growth rates and the probability of decline at current harvest levels were determined for 13 subpopulations of polar bears (Ursus maritimus) that are within or shared with Canada based on the most recent demographic and harvest statistics using population viability analyses (PVA). Aboriginal traditional ecological knowledge (TEK) on subpopulation trend agreed with the seven stable/increasing results and one of the declining results, but disagreed with PVA status of five other declining subpopulations. The decline in the Baffin Bay subpopulation appeared to be due to over-reporting of harvested numbers from outside Canada. The remaining four disputed subpopulations (Southern Beaufort Sea, Northern Beaufort Sea, Southern Hudson Bay, and Western Hudson Bay) were all incompletely mark-recapture (M-R) sampled, which may have biased their survival and subpopulation estimates. Three of the four incompletely sampled subpopulations were PVA identified as non-viable (i.e., declining even with zero harvest mortality). TEK disagreement was non-random with respect to M-R sampling protocols. Cluster analysis also grouped subpopulations with ambiguous demographic and harvest rate estimates separately from those with apparently reliable demographic estimates based on PVA probability of decline and unharvested subpopulation growth rate criteria. We suggest that TEK can be used as a reliable correspondence test to evaluate scientific results independent of the assumptions of the scientific analysis models. Considering TEK as reliable for subpopulations where scientific information is suspect (unreliable), we suggest that the current status of Canadian polar bear subpopulations is 12 stable/increasing and one declining. We do not find support for the perspective that polar bears in Canada are currently in any sort of climate crisis. We suggest that climate warming, sea ice decline, and polar bear monitoring should be improved, and that adaptive management practices should be employed as warranted.