Spatiotemporal variation in Arctic char (Salvelinus alpinus) foraging ecology along western Hudson Bay, Nunavut, Canada

Abstract

Climate-induced alterations to Arctic sea ice dynamics are influencing resource availability and distribution, and in turn, restructuring Arctic marine food webs, which can be monitored by studying the foraging ecology of opportunistic predators such as anadromous Arctic char (Salvelinus alpinus). Despite its subsistence and economic importance, Arctic char foraging ecology across their range, particularly in relation to sea ice dynamics, remains understudied. Here, we investigate the foraging ecology of Arctic char near the communities of Rankin Inlet and Naujaat along western Hudson Bay, using stomach contents, stable isotopes (δ13 C and δ15 N), and highly branched isoprenoids. Spatiotemporal variation in diet was observed in relation to sea ice dynamics, whereby Arctic char in Rankin Inlet consumed more fish and phytoplankton-based carbon, occupied a higher trophic position, and displayed a similar isotopic niche breadth compared to Naujaat. The plastic foraging ecology observed highlights the species’ adaptability to inter-annual variability, although long-term resilience in response to climate-driven changes remains unknown.