The optimization of microsatellite genotyping and genetic sexing of non-invasively collected polar bear tissue: Implications for monitoring and census.

The monitoring of Polar Bears in Canada has been completed largely through management unit (MU) wide capture-mark-recapture (CMR) surveys. While this data is very useful at the time of collection, these surveys are expensive and take time to plan and execute; cannot be feasibly executed across the polar bear range at intervals that reflect the expected rapid environmental changes in the Arctic; and are disdained by the Inuit as being invasive. As part of recent efforts to explore less expensive and non-invasive methods to monitor polar bears (see Wong et al & Van Coevderden de Groot et al this conference) we are evaluating genetic information obtained from non-invasively collected polar bear tissue. In this work we report on the genetic data obtained from non-invasively collected harisnags recovered from sampling stations erected between May-June 2006-2009 in M’Clintock Channel, Nunavut. Across the 4 years 344 hair snags were collected; following Paetkau (2004) we optimized 6 microsatellite loci to reliably amplify polar bear DNA from this tissue and we modified the procedure of Pages et al (2009) to reliably genetically sex these tissues. Our estimates for two common errors with this type of tissue across all loci – allelic dropout (0.026) and false allele (0.03) - were both less than p =.05. This suggests these errors are not going to significantly affect the accuracy of the consensus genotypes collected from these data. Using consensus genotypes from relevant hairsnags, we posit a minimum of 59 (max 82) unique bears entered our sampling stations. Of these, 24% were female, 64% were male, and 12% could not be sexed. We resampled 2 bears in 2006, 1 in 2007, 0 bears in 2008 and 14 bears in 2009 – the 2009 value reflects significantly increased sampling effort in 2009. Five bears were re-sampled between the non-invasive surveys in 2006-2009. When comparing our data to a subset of cubs and subadults captured during the Taylor et al. (2006) CMR survey of M’Clintock Channel (MU), we found 6 genotype matches. Our sampling stations may have a male bias as the sex ratio from the 1998-2000 CMR study was 42.1% ♂ (Taylor et al 2006) vs. 64% ♂ (this study). We cannot accurately determine the age bias (but see Wong et al this conference). Genetic data from Polar bear faecal samples may provide an unbiased sex and age sample of polar bears in any MU. Any data from these samples will help refine hairsnag derived MKNA estimate of polar bears from any MU. Here we report on our efforts to genotype and genetically sex 95 faecals we have collected from M’Clintock Channel from 2006-2009. Finally, we discuss the implications of these findings, results from other noninvasive work (Wong et al & Van Coevderden de Groot et al this conference) and ongoing/proposed work in the context of i) a non-invasive Inuit-based polar bear activity and health survey, and ii) a more rigorous census method which may allow more precise adjustments of harvest levels than currently possible using infrequently collected CMR data only.

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