Abstract
Assessing variation in social behaviors of group‐living animals may provide insight into the impacts of population stressors. Using very high resolution (VHR) satellite imagery acquired over 3 years, we compared social group size and composition, as well as spatial and social cohesion in three beluga ( Delphinapterus leucas ) populations that experience different levels of harvest and vessel traffic exposure: Cumberland Sound, Eastern High Arctic‐Baffin Bay, and Western Hudson Bay. We further explored the relationships between harvest, vessel activity, beluga density, and social context with beluga grouping characteristics to predict potential drivers of beluga social group dynamics. Mean group size decreased with harvest levels, possibly reflecting the effects of population decline or removal of key social individuals. Populations exposed to recent increases in vessel activity were associated with larger group sizes and greater spatial cohesion, possibly suggesting increased vigilance in response to vessel traffic. Adult‐juvenile mixed groups were larger and had smaller inter‐group distances than groups comprised of adults only, likely reflecting the dependence of younger whales on alloparental care. This study provides a novel application of VHR satellite imagery for beluga monitoring and highlights potential impacts of anthropogenic stressors on beluga populations.