Using genetics to test the theory that 1) Atlantic salmon mortality at sea is linked to climate change, and 2) subsistence fishing is impacting Atlantic salmon population recovery

Description

A majority of salmon populations in the Northwest Atlantic are threatened or at risk of extinction and estimates of the impact of climate change and subsistence harvests are central to rebuilding and recovery strategies. By identifying genes associated with climate change and genetic adaptation in Atlantic salmon, this work provided an opportunity to discover the overall role of climate change in the decline of Atlantic salmon, the strength of genetic selection and potential to adapt to the impacts of climate change on salmon health (heat tolerance, in particular). This project also helped to quantify the exploitation of specific populations in the subsistence harvests of Atlantic salmon in the Northwest Atlantic. The combination of precise molecular markers with specific statistical approaches provided a unique opportunity to explore catch composition, movements, and mortality of Atlantic salmon in Canadian waters.

Given that the goal of this research was directly related to the protection of Atlantic salmon stocks from the effects of climate change and subsistence fishing, it became important to first determine which genetic markers would be best to use. Searching all available information (including published literature and publicly available DNA sequences) made it possible to verify DNA markers (microsatellites) which were best associated with heat tolerance genes (indicating the species’ ability to cope with warming waters). Using previously existing markers that were chosen based on their association with immune responses also aided researchers to test for evidence of genetic selection from each of six populations of Atlantic salmon. Neutral (non-gene associated) markers, representing the species’ western Atlantic range, were used to estimate the proportion of stocks present in mixed harvests in the waters surrounding Newfoundland and Labrador.