Co-Occurring salmonids: assessing diet overlap among chum and sockeye salmon with arctic char and dolly varden in the Canadian Arctic

Background/Question/Methods

The cumulative effects of climate change are driving many species northward, leading to questions regarding interactions between Arctic and sub-Arctic species. Direct and indirect changes associated with climate have increased the potential for competition for both habitat and prey. The recent increased presence of Pacific salmon in the western Canadian Arctic has raised concerns among local communities given the potential for competition with endemic fishes, especially those important for subsistence fisheries. Stomach contents and stable isotopes were analyzed from two endemic species of anadromous char (Arctic Char Salvelinus alpinus and Dolly Varden Salvelinus malma) and two species of Pacific salmon (Chum Salmon Oncorhynchus keta and Sockeye Salmon Oncorhynchus nerka) collected among three Beaufort Sea communities where these species co-occurred in summer 2017. All samples were collected from ongoing community-based fisheries monitoring programs along coastal waters within the Inuvialuit Settlement Region.

Results/Conclusions

Analyses of stable isotopes and stomach contents indicated char and Pacific salmon do not overlap in diet during the summer marine foraging season, and thus are unlikely to compete for prey during their adult life stages. This assessment of dietary overlap contributes to informing ecosystem and fisheries co-management under rapidly changing environmental conditions, and is necessary in order to evaluate how increased salmon prevalence may affect important fisheries.