Introduction of exotic salmonids to aquaculture in eastern Canada and Maine

A long history of introductions of rainbow trout and more recent introductions of Arctic charr appear not to have impacted the local salmonid populations of eastern Canada and Maine. A few isolated feral populations of rainbow trout have been established but they appear to be in decline. There is no evidence of any feral Arctic charr populations becoming established despite known escapement. The consensus is that both species are poor colonizers and a low risk when grown in aquaculture settings. However, the use of exotic Atlantic salmon strains in aquaculture has resulted in new gene introgression into local populations. This is most evident when transatlantic strains have been imported. The adaptive significance of this introgression is not known, but is under scrutiny. Genetic selection applied to local salmon strains to adapt them to aquaculture practices has significantly modified their genotypes. However, the genetic consequences to wild strains of the wide distribution of aquaculture strains throughout Atlantic Canada and Maine are unknown.