First Glimpse into Parasites of Arctic Anadromous Lake Trout

Partial anadromy, where some individuals remain in freshwater while others migrate to sea, is common at northern latitudes. These life history differences can have ecological consequences impacting the parasite infracommunity, as parasite exposure varies due to differences in habitat use and foraging ecology. Lake trout (Salvelinus namaycush, Walbaum in Artedi, 1792), typically a freshwater species, exhibits partial anadromy at high latitudes, making them an ideal species for examining parasite richness across different habitat types. Here, we assessed macroparasites in the viscera of ten lake trout (marine: n=7; freshwater: n=3) sampled near Iqaluktuuttiaq, Nunavut. Fifteen parasite taxa were identified. Marine-captured trout were dominated by cestode Proteocephalus spp. Weinland, 1858, and trematodes Derogenes spp. Lühe, 1900, and Brachyphallus crenatus (Rudolphi, 1802) Odhner, 1905, while freshwater fish hosted nematode Hysterothylacium spp. Ward & Magath, 1917, cestode Eubothrium salvelini (Schrank, 1790) Nybelin, 1922, and acanthocephalan Echinorhynchus spp. Zoega in Müller, 1776. Parasite richness and abundance was higher in marine individuals. Our study provides the first description of anadromous lake trout parasites, while advancing our understanding of life history variation and ecology of this species. As Arctic environments rapidly change and parasite exposure can shift, such baseline biodiversity data are essential for future monitoring.