On average, levels of omega-3s halved in the fish over the past five years. The industry is exploring new ways to arrest the decline – which appears to be due to the type of feed given to the farmed fish. The study was carried out by researchers at Stirling University. Prof Douglas Tocher, who led the research, told BBC News: “About five years ago, a portion of Atlantic salmon of 130g was able to deliver three-and-a-half grams of beneficial omega-3. This is actually our weekly recommended intake. Now, the level of omega-3 has halved,” he said.
The farmed salmon get their omega-3s from smaller oily fish such as anchovies, which have been ground up and added to their feed. The more oily fish that goes into the feed, the more omega-3 the salmon contains. Not long ago, 80% of the feed was made up from oily fish. Now, it’s more like 20%.