Transforming salmonid aquaculture from a consumer to a producer of long chain omega-3 fatty acids

Recommendations to endorse the sustainability of wild fish stock utilisation, supporting the health of marine ecosystems, are clashing with those to increase omega-3 fatty acids ( n− 3 LC-PUFA) consumption and promoting human health. The objective of this study was to evaluate the role of salmonid aquaculture as a user or supplier of n− 3 LC-PUFA, as a means of understanding the potential of the sector in conserving or depleting wild fisheries. A case-study feeding trial was implemented on rainbow trout up to commercial size, in which fish were fed a fish oil- or a linseed oil-diet. Harvested fish were analysed for fatty acid composition and difference and liking using consumers. The n− 3 LC-PUFA input/ n−3 LC-PUFA output ratio was computed. Consumers showed no preference, but were able to distinguish between samples. The fatty acids of the fillets were significantly modified by the diets. On the input side, for the production of 100 g of fish fillet, it was necessary to use 8.6 g of n−3 LC-PUFA to produce an output of 1.9 g of n−3 LC-PUFA in the fish oil-fed fish; in contrast it was only necessary to use 270 mg of n−3 LC-PUFA to produce 560 mg of these fatty acids in the linseed oil-fed fish. It was showed that the substitution of fish oil with linseed oil in aquafeed is an easily implemented tool to transform salmonids farming from a consumer into a net producer of health promoting n−3 LC-PUFA and accomplish its role in conserving wild fisheries in the future.