Using Decontaminated Fish Oil or a Vegetable/Fish Oil Blend to Reduce Organic Contaminant Concentrations in Diets and Flesh of Farmed Atlantic Salmon (Salmo salar)

Abstract

First paragraph: The nutritional and health benefits of consuming seafood are well documented and are based on the virtually unique supply of n-3 highly unsaturated fatty acids (HUFA), as well as essential vitamins and minerals, in fish and shellfish1. Global food grade fisheries have reached a plateau at around 90m tonnes/annum while in 2004 aquaculture contributed over 28m tonnes to the human food basket2. Growth of aquaculture is predicted to continue over forthcoming decades, at a rate between 1.9 and 3.3%/annum, as the demand for fish in general and the consumption of aquaculture products increases to fill the gap in demand that cannot be met by capture fisheries. Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss), account for more than 80% of total European aquaculture production with Norway being the major producer in Europe with Chile producing similar production volumes. Salmon is an oil-rich species and contains high concentrations of health beneficial n-3 HUFA3. However, as with all oily carnivorous fish, the oil rich tissues can accumulate lipophilic organic pollutants, including dioxins/furans, polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs), derived largely from their feed4. There has been considerable recent focus on the transfer of organic pollutants from fish feed to farmed fish and possible consequences for human health5, and subsequently on approaches to reduce levels in feed and farmed Atlantic salmon6. As fish oil is the main contributor of contaminants to fish feeds we investigated the effects of replacing northern fish oil, with high levels of contaminants, with either decontaminated fish oil or a blend of fish oil and a 1:1 (w/w) blend of soya and rapeseed oils. The results of these 3 treatments on dioxin, dioxin-like (DL) PCB and PBDE concentrations in fish feed and flesh are described below.