Demographic assessment using physical and genetic sampling finds stable polar bear subpopulation in Gulf of Boothia, Canada

Abstract

Knowledge of long-term demographic trends is important for managing large carnivore populations under changing environmental conditions, management objectives, and human values. From 2015 to 2017, we biopsy-sampled polar bears (Ursus maritimus) in the Gulf of Boothia (GB) subpopulation to genetically identify individuals. This less-invasive sampling method was more compatible with stakeholder values than chemical immobilization. We analyzed the biopsy data together with live-capture study data (1998–2000), opportunistically collected live-capture data (1976–1997), and harvest recovery data (1976–2017). From 2015 to 2017, the mean model-averaged abundance estimate was 1,525 bears (SE = 294), similar to both the 1998–2000 estimate from the current analysis (1,610 ± 266) and previously published estimate (1,592 ± 361). Total survival from 2015–2017 varied by sex and age class, with higher estimates for adult females (0.95, 95% CI [0.81, 0.99]) than adult males (0.85, 95% CI [0.74, 0.92]). Mean number of yearlings per adult female was 0.36, 95% CI [0.26, 0.47], suggesting healthy reproduction. Body condition improved between 1998–2000 and 2015–2017. Our findings suggest the GB subpopulation is currently productive and stable. Forecasts of continued sea-ice loss and environmental change due to climate warming emphasize the need for ongoing monitoring of this subpopulation.