Differences in energy acquisition and storage of farm, wild, and hybrid Atlantic salmon competing in the wild

An understanding of genetic differences in fitness-related traits for farm, wild, and hybrid Atlantic salmon ( Salmo salar) is key for predicting impacts of aquaculture escapes on wild populations. Here we used lipid and fatty acid (FA) analyses to investigate differences in storage and foraging ability among Atlantic salmon juveniles of three cross types (farm, wild, and F1 hybrids), at the beginning and end of a common garden experimental release in the Newfoundland wild. We found differences in lipid class and FA profiles among cross types at both release and recapture, with farm fish being the most differentiated at recapture. In addition, low recapture levels of triacylglycerols and certain FAs indicative of freshwater prey suggest the possibility of a feeding disadvantage for farm fish. Overall, we show that lipid and FA profiles in juvenile salmon can change over just a short period of time even under favourable conditions in the wild, and farm fish may have genetic differences affecting energy acquisition and storage that could negatively impact their survival and fitness in the longer term.