Spatiotemporal Variation in the Foraging Ecology, Habitat Use, and Distribution of Arctic Marine Mammals in Relation to Sea Ice

Abstract

The Arctic is shifting under climate change, with loss of sea ice altering marine ecosystem structure. This thesis examined two Arctic marine mammals: Bowhead whales (Balaena mysticetus) and ringed seals (Pusa hispida), both being at risk of the effects of sea ice loss. Using biomarker analysis for bowhead whales (δ13C, δ15N, fatty acids) and observations from aerial surveys for ringed seals, this study investigated spatiotemporal variability in (1) foraging of bowheads from 1993-2023 in the eastern Canadian Arctic and (2) density and distribution of ringed seals from 1994 to 2024 in Western Hudson Bay, Canada.

The biomarker results indicated spatiotemporal shifts in bowhead whale diet, including a nonlinear relationship between δ13C and sea ice concentration, declining δ15N values, narrowing of isotopic niche widths, and shifts in fatty acid profiles- especially in Hudson Bay. Ringed seal density declined from 1994-2024, with sea ice and distance to shore as key predictors.