Sara Bolduc

Parasites play a critical yet understudied role in Arctic ecosystems, particularly within key subsistence species such as Arctic char ( Salvelinus alpinus ). As the Arctic undergoes rapid climate-driven change, establishing baseline parasite biodiversity is essential for monitoring ecological shifts and anticipating emerging health and conservation concerns. This study provides the most comprehensive assessment to date of Arctic char parasites in the North American Arctic by integrating a systematic literature review with new empirical data from 378 Arctic char collected across five Nunavut areas (2020–2024). The literature review (30 studies, 1956–2024) documented 67 parasite taxa—48 identified to species—with helminths (nematodes, cestodes, trematodes, acanthocephalans) dominant. Overall, 82% of taxa occurred in anadromous Arctic char and 54% in freshwater forms, including 22 species unique to anadromous fish. Our empirical assessment identified 35 parasite taxa—23 to species level—including several previously unreported from Arctic char in this region. Common and widespread parasites documented in the empirical assessment included Brachyphallus crenatus , Derogenes varicus , Bothrimonus sturionis , and Alloopistholecithum gibbosum , although notable spatial variation occurred in community composition and infection intensity. The occurrence of rare and previously unreported parasites may suggest emerging shifts in host–parasite dynamics potentially linked to changing prey availability and northward species range expansions. Together, these findings establish an essential baseline for Arctic char parasite biodiversity and highlight the need for continued monitoring to track future changes driven by climate warming, shifting food webs, and their implications for fish health and food security in northern Indigenous communities.

Arctic char ( Salvelinus alpinus) is a salmonid fish that is the second-most consumed country food species by Nunavimmiut. Its nutritional quality is determined by omega-3 fatty acids and carotenoid pigments. Those molecules cannot be synthetized by fish and must be acquired through diet. We sampled Arctic char in 10 rivers from the three marine coastal regions of Nunavik (Hudson Bay, Hudson Strait, and Ungava Bay), described diet (stable isotopes δ¹³C and δ¹⁵N) and flesh quality (fatty acids and carotenoids, measured by chromatography) and assessed associations between both diet and flesh quality (including also bio-impedance and colorimetry). Our results suggested inter-regional differences in the diet and nutritional quality of Arctic char in Nunavik, where δ¹³C values indicated that the diet of Arctic char in Hudson Bay was more pelagic, while in Ungava Bay it was more coastal. We also observed inter-regional differences in omega-3 fatty acids and astaxanthin, the pigment responsible for the redness of the flesh color, where concentrations were highest in Ungava Bay Arctic char. In all sampling locations, Arctic char were an exceptional source of omega-3 fatty acids and astaxanthin, confirming its importance as a high-quality wild food. Our models suggest that astaxanthin, canthaxanthin, and water content influence flesh redness. Our data highlight inter-regional differences that could be taken in consideration to better predict the impact of climate change on fish quality and, ultimately, on Inuit diet and health.