Evaluating harvest risk with limited data: A case study on polar bears (Ursus maritimus) in East Greenland

Abstract

Evaluating the impact of human-caused removals on wildlife is challenging, especially when population data are limited, future monitoring is uncertain, and habitat conditions are changing. The East Greenland (EG) polar bear subpopulation contains 2275 animals (95% CI = 1360–3807) and is a subsistence resource for Indigenous Peoples. We developed a state-dependent modeling and management framework to evaluate different harvest strategies for EG bears. Our approach considered sea-ice loss and followed international consensus principles for the sustainable harvest of polar bears. Over the next 34 years (approximately three polar bear generations) and assuming a 2:1 male-to-female harvest sex ratio, the starting sustainable harvest ranged from 63 bears/year in the absence of scientific monitoring, to 93 bears/year if updated demographic parameters are estimated after 15 years and used to adjust the harvest, if necessary. We also identified an intermediate harvest strategy of up to 78 bears/year that requires a moderate level of monitoring and uses a threshold harvest rule. Our findings demonstrate how monitoring can make it possible to safely implement higher sustainable harvest levels (i.e., approaching maximum sustainable yield). Our methods are relevant to wildlife managers seeking to balance demographic risk, investment in monitoring, and opportunities for subsistence use.