Chemical contaminants in aquafeeds and Atlantic salmon (Salmo salar) following the use of traditional- versus alternative feed ingredients

Marine feed ingredients, traditionally used in commercial fish feeds, are the source of these pollutants in farmed fish. The aim of the study was to assess the chemical contaminant load in Atlantic salmon (Salmo salar L.) raised on novel sustainable feeds based on a combination of alternative ingredients. Atlantic salmon were reared on feeds based on either traditional or alternative feed ingredients for an entire seawater production cycle up to approximately 4 kg, which is a typical market-size for this species. The levels of several notorious contaminants were analysed in feed ingredients, feed, and skin-off fillets. These included persistent organic pollutants (POPs) such as polychlorinated biphenyls (PCBs), dioxins and furans (PCDD/Fs), organochlorine pesticides (OCPs), and polybrominated diphenyl ethers (PBDEs), as well as elements such as arsenic, mercury, cadmium, lead, copper, zinc and fluorine. In addition, poly-aromatic hydrocarbons (PAHs) were analysed. The use of alternative feed ingredients reduced the fillet load of POPs by 51–82% and the level of arsenic and mercury by 80–96%. In contrast, the PAH levels in fish reared on the novel feeds were significantly (p < 0.05) higher than the PAH concentrations in traditionally-raised fish. The present study shows that developments in feed formulation will reduce the load of most persistent organic pollutants in farmed salmon, but may increase concentrations of other contaminants such as PAHs, which are normally not associated with Atlantic salmon. The paper also compares the levels of contaminants in farmed Atlantic salmon expected in the future with those levels reported in the literature and currently on the market.