![]() Because polar bears occupy remote and environmentally extreme habitats, population monitoring for conservation and management is challenging, costly, and becoming more difficult with rapidly changing environmental conditions. Given the obligations of the ESA, international management agreements, and the need to ensure that subsistence harvest is sustainable, polar bear populations need to be monitored and managed. The US shares two polar bear subpopulations (Chukchi Sea (CS) and Southern Beaufort Sea (SBS)) with Russia and Canada respectively ( Figure 1), and Indigenous people legally hunt polar bears for subsistence from both subpopulations. As sea ice continues to decline, polar bears are expected to spend more time on land ( Rode et al., 2022), thereby increasing the potential for human/bear conflicts and negative impacts on cub survival due to human disturbance ( Woodruff et al., 2022). The loss of sea ice due to climate change in the Arctic ( Rantanen et al., 2022) led to the listing of polar bears as “threatened” under the US Endangered Species Act (ESA) ( US Fish and Wildlife Service, 2008). The polar bear ( Ursus maritimus) is an iconic Arctic predator that relies upon sea ice as a platform on which to hunt, travel, and reproduce ( Wiig et al., 2015). It also can involve, engage, and empower Indigenous communities in the Arctic, which are greatly affected by polar bear management decisions. This method is non-invasive, could be integrated into genetic mark-recapture sampling designs, and addresses some of the current challenges arising from poor sea ice conditions. To our knowledge, this is the first time that polar bears have been individually identified by genotype and sex using e-DNA collected from snow. ![]() Six of the 13 bear trails sampled (46%) yielded consensus genotypes for five unique males and one female. Identification of individuals was accomplished by amplifying a multiplex of seven n-DNA microsatellite loci, and sex was determined by the amelogenin gene sex ID marker. Species verification was based on a mt-DNA PCR fragment analysis test. Snow was sampled from 13 polar bear trails (10 paw-prints per trail) on the sea ice in the Chukchi and Beaufort seas along the North Slope of Alaska. The goal of this investigation was to assess the viability of using e-DNA collected from paw-prints in the snow to identify individual polar bears and their sex. Mitochondrial DNA ( mt-DNA) is used to assess whether polar bear DNA is present within a snow sample, and nuclear DNA ( n-DNA) can identify individuals and their sex. However, epidermal cells shed from the foot pads of a polar bear into its paw-prints in snow are a source of “environmental DNA” ( e-DNA) that can be collected non-invasively on the sea ice or on land for potential use in population monitoring. One common method utilizes biopsy darts delivered from a helicopter to collect DNA, a method that faces similar ice associated challenges to those described above. ![]() Monitoring polar bears via DNA sampling is a promising option. These methods largely rely upon the capture and handling of polar bears, and have been criticized over animal welfare concerns. Population monitoring is vital to polar bear conservation but recently, poor sea ice has made traditional aircraft-based methods less viable. Declining sea ice extent and duration has led polar bears to be designated as “threatened” (ESA). Polar bears rely upon sea ice to hunt, travel, and reproduce.
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