Spring conditions and habitat use of beluga whales (Delphinapterus leucas) during arrival to the Mackenzie River Estuary.

Climate change is expected to impact Arctic marine mammals, as they may be particularly vulnerable to large annual variability in the environment. Beluga whales (Delphinapterus leucas) occupy the circumpolar Arctic year-round, and seasonal movement patterns in this landscape are closely linked to sea ice and changing conditions. Here, we examine the association between beluga spring locations along the Mackenzie Shelf and three relevant habitat variables: sea ice (total concentration, floe size, and distance to ice edge), bathymetry and turbidity. Beluga locations in 2012 and 2013 were analyzed across the study area, as well as in three discrete subareas of the Mackenzie Shelf: Shallow Bay, Kugmallit Bay and Tuktoyaktuk Peninsula. In both years, beluga were found more than expected by chance in locations of open water/light ice concentrations and medium ice floes, and displayed a significant association with turbid water (i.e., increased freshwater flow). Largely ice-free conditions in 2012 led to a wide variation in habitat use in all three subareas. Beluga whales in 2012 preferred the ice edge and were found in heavier ice concentrations, larger floes and high turbidity water in the Shallow Bay subarea. Open water environments were preferred by beluga found in the Kugmallit Bay subarea. In contrast, heavy ice conditions in 2013 resulted in restricted habitat use and selection of shallow depth (<50 m) and low levels of turbidity. These results provide knowledge on spring habitat selection as well as insight into the adaptability of beluga under expected changes associated with climate and human activity in the Beaufort Sea.