Atlantic salmon diets in the wild vary depending on the availability of wild fish and crustaceans containing carotenoids which give wild salmon their characteristic flesh colour.
Based on this understanding of salmon nutrition, ‘pelagic species such as anchovy were added to the wet feeds that were used in the early days of salmon aquaculture. As the salmon industry expanded and created more mechanised feed substances through the use of commercialised feed pellets in the 1980’s, pelagic fish such as anchovy and sardines were rendered into Fish Meal and Fish Oil that were the main source of protein and oils in feed pellets.
Salmon farming is one of the most reliant of all aquaculture industries on fish meal and fish oil products as salmonids are a carnivorous top end predator fish. As of 2013 salmon aquaculture accounted for just ‘seven percent of total global aquaculture production , while utilising 26 percent of all fish meal and 68 percent of the fish oil used in aqua feeds . The average percentage of fish meal and oil in salmon feed is thirty percent. Huon Aquaculture states that it takes 1.69kg of forage fish as fish oil for every kilogram of farmed Tasmanian salmon.
Average percentage of Tasmanian farmed Atlantic Salmon feed ingredients as stated by Huon Aquaculture
The exact ingredients in specific aquaculture feed ranges are not publicly disclosed, except for broad mandatory labelling on feed packets. The exact sources of these ingredients are difficult to determine even when contacting each individual manufacturer for that information.
As the saying goes you are what you eat. This is certainly the case in regards to salmon as healthy fats like Omega 3 people are seeking out when choosing fish. The fatty acid (including Omega 3 and 6) profile and quality of the aquafeeds is reflected in the fatty acid profile of salmon flesh , which is then ingested by the consumer. Salmon, like humans, need Omega 3 from their diets, which is most readily available from the fish meal component, rather than plant oil content of manufactured feeds.
We asked Skretting, Ridley and BioMar for information on the ‘growth promoting feed’ ranges featured on their webpages, as well as the ‘high heat stress’ feeds, and ‘juvenile feeds’ promoted. None of the companies provided information on specific feed types listed on their webpage or were prepared to outline how their advertised ranges are designed to accelerate growth, appetite or the ability for fish to survive longer when heat stressed as advertised. Given that studies have recently discovered that 50 of farmed salmon are deaf because accelerated growth rates prevent their ears from developing, these questions are crucial from an animal welfare perspective.
A 2013 sustainability study of the Tasmanian salmon industry conducted by Amelia White of Bond University provided an overview of the average ingredient composition of commercial salmon feeds.