Detecting hybridization among wild and farmed escaped Atlantic salmon in southern Newfoundland: Field collections

Description

Aquaculture escapees represent a continued threat to the genetic integrity of wild populations, and have been shown to interbreed with wild fish, which can impact local adaptation. In southern Newfoundland, wild Atlantic salmon populations remain at record lows and their status is considered “threatened” by COSEWIC. Potential impacts associated with the developing aquaculture industry cannot be ruled out as a contributing factor on the survival of wild fish. In 2013, a large escape event (>20,000 individuals) occurred in southern Newfoundland where there were reports of mature escapees in local rivers. Given the magnitude of this escape event, a study was designed to determine if interbreeding occurred (i.e., hybridization) and if the samples of young-of-the-year Atlantic salmon contained a mixture of wild and hybrid individuals. Future genomic screening of these samples will be used to quantify the rates of successful hybridization and evaluate the potential genetic impact of aquaculture escapees on wild populations in Newfoundland and Labrador.