Estimating diets of Atlantic salmon (Salmo salar) using fatty acid signature analyses; validation with controlled feeding studies

Diets incorporating homogeneous binary mixtures of herring or krill oil were fed to Atlantic salmon ( Salmo salar ) for 22 weeks, and belly flap and muscle tissues were then analyzed for fatty acid (FA) composition. Quantitative fatty acid signature analysis (QFASA) was able to estimate proportions of major dietary components within ∼10% of actual values, but the accuracy of the estimates depended on the FA set and calibration coefficients (CC) used in the modelling. FAs present at low levels had little influence on estimates, despite having only dietary sources; the FA set used in the modelling must incorporate the major FAs in tissues to ensure accurate estimates of diet. CC, which reflect modifications that consumers make to dietary FAs, were similar in the two tissues but varied with diet. When CC were applied to correct for fish metabolism, QFASA tended to overestimate the dietary component that had been fed to determine the CC. Diet estimates were most accurate when CC that had been developed from feeding the krill oil-based diet were applied. This first application of QFASA to fish therefore establishes a set of FAs and CC to begin to investigate diets of salmonids.