Genetic influence on survival and fitness-related traits of juvenile farmed, wild, and hybrid Atlantic salmon (Salmo salar) in nature

Crowley, Samantha E. (2021) Genetic influence on survival and fitness-related traits of juvenile farmed, wild, and hybrid Atlantic salmon (Salmo salar) in nature. Masters thesis, Memorial University of Newfoundland.

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Abstract

Farmed Atlantic Salmon (Salmo salar) have experienced multiple generations of selection pressures different from those experienced by their wild counterparts. Farmed fish escape from aquaculture facilities regularly, and their interbreeding with wild fish can result in lower wild population productivity and altered life history traits. Therefore, understanding the genetic basis of relative performance of farmed, wild, and hybrid salmon is critical to predicting impacts on wild populations from farmed escapees. In my first data chapter, I compared the relative survival, size, morphology, and parr marks of Atlantic Salmon parr (wild, farmed, and reciprocal F1 hybrids) over the first summer of growth at three replicate sites in southern Newfoundland. There was a consistent pattern of relative survival across all sites (wild-mother hybrids > pure wild > pure farmed > farmed-mother hybrids), with wild fish consistently smallest in size, and wild-mother hybrids and farmed fish largest. In addition, I found small differences in body shape related mainly to body depth, and differences among sites for parr mark size. In my second data chapter, I compared lipid and fatty acid profiles at release and recapture for farmed, wild and hybrid parr. There were lipid profile differences among cross types at both time points and in addition, pure farmed fish displayed a greater decrease in storage lipids and certain fatty acids characteristic of freshwater invertebrate prey over the experimental period when compared with other cross types. Overall, there were measurable differences in survival and fitness-related traits among cross types, even over a relatively short experimental period under favourable conditions. Ultimately, this research provides key data on relative cross type performance for North American populations of Atlantic Salmon that may help inform predictive models, and subsequent aquaculture management and mitigation decisions.

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