Project Year 2016
How much omega-3 do salmon need?
Humans and fish need omega-3 in their diets. But supplies are short, and farmed salmon now have less omega-3 in their diet than previously.
The question is just how little marine omega-3 can farmed salmon get by with. Too little omega-3 can pose a health risk.
Nofima and NIFES have examined all the available data about safe low levels of marine omega-3 in feed for farmed salmon, while still ensuring good fish health.
The results are presented in the report “Fats for fish health – 2016”.
In short-term tests on land, researchers have found that the fish can get by with less than 1% marine omega-3 in their diet. Results from long-term trials in sea pens, indicate that an omega-3 content of 1.6% and over does not have a negative impact on growth or survival.
It was previously thought that 1% was an acceptable level, but recent experiments show that this level is not sufficient in practice in sea cages.
“Varying environmental conditions in the sea mean that multiple factors affect the salmon’s need for marine omega- 3. An omega-3 level that is good enough for fish under ideal farming conditions may not be sufficient in more demanding environmental conditions,” explains Nofima scientist Bente Ruyter.
The content in current commercial feed varies, but all have over 1.6%.Nofima and NIFES have tested whether different levels of omega-3 affect fish health. These experiments showed that too little omega-3 can make salmon less robust and more prone to develop viral diseases.
The researchers knows that the composition of the fats in the diet affects the distribution of fat in salmon, which can in turn affect the course of viral infections.
“There is still a fair degree of uncertainty, so we are not yet able to say exactly how little omega-3 is safe in commercial production of farmed salmon,” says Ruyter.
IN COOPERATION WITH:
NIFES (project manager)
The Research Council of Norway (NFR) and the Fishery and Aquaculture Industry Research Fund (FHF)