Population Genetic Analyses of Arctic Char (Salvelinus Alpinus) Life History Types in Nettilling Lake & Amadjuak River Ecosystem: A Test of Reproductive Isolation

A great number of studies have identified strong genetic differences between sympatric anadromous and resident populations of Salmonidae. However, Arctic char (Salvelinus alpinus) migratory phenotypes in the Nettilling Lake and Amadjuak River ecosystem in Nunavut, Canada have not been genetically characterized, and it remains unclear if distinct genotypes and phenotypes associated with migratory life history differences are maintained through reproductive isolation, and they have been assumed to be sympatric populations, or co-occurring populations. Co-occurring Arctic char (n=225) were sampled from eleven sites along the Amadjuak River in 2014 and 2015. Twelve microsatellite loci were used to quantify genetic variation among the sampled fish. The genetic data showed two genetic clades (populations) of Arctic char living in the ecosystem. However, each genetic population contained both resident and anadromous individuals (migratory life histories). These results suggest that genotype should be considered when identifying populations of Arctic char for conservation and management purposes. Fish from the two different clades were captured at the same site, indicative of possible sympatry, increasing the complexity of effective management of this important fishery resource. We thus suggest using genetic methods to categorize individual fish to their respective genetic population, while further work should be done to explore morphological and physiological trait differences to simplify the management of the fish from the two cryptic populations.