Complementary diet analyses reveal intraspecific and temporal variation in ringed seal ( Pusa hispida ) foraging in the Canadian high arctic

Warming ocean temperatures and loss of Arctic sea ice have contributed to shifts in the distribution of endemic forage species important to the diets of marine carnivores, such as ringed seals ( Pusa hispida ). Given the heterogeneous way in which these changes are projected to occur throughout the Arctic, it is important to gain an understanding of predator diets and how they may change over time and space. We present the first study of ringed seal foraging ecology in the Gulf of Boothia, located in the central Canadian Arctic, using three diet estimation techniques: stomach contents, stable isotopes, and fatty acid signature analyses. Samples of ringed seal blubber and muscle were collected during subsistence harvests in Kugaaruk, Nunavut, Canada between 2012 and 2016. Stomach contents were collected in 2012 and differed amongst seals of different age classes, with polar cod ( Boreogadus saida ) comprising the largest proportion of both adult and juvenile seal diets. Mysids ( Mysis oculata ) were the main prey consumed by young of the year. Overall, FA signatures differed amongst age classes and exhibited significant interannual variation, but were not influenced by sea ice phenology, whilst values of δ 13 C, an indication of foraging habitat, changed in relation to the dates of annual sea ice breakup and freeze-up. Our results offer novel insights into the foraging habits of ringed seals in the Gulf of Boothia and demonstrate that ringed seal diets vary temporally, although not solely in response to sea ice concentration, which remains relatively high in this region of the central Canadian Arctic.