In October 2016 BBC News flagged up that the average omega-3 essential fatty acid content of salmon grown in Scotland’s salmon farms had halved over the last five years. The reason, apparently, was that the fish had once been fed a ‘turbofeed’ comprising 80% small oily fish (like anchovies) to make them grow faster and larger, but are now fed a more balanced feed comprising only 20% small oily fish and 80% vegetable oils and plant protein.
This may not only be simple cost-cutting or profit maximisation. The salmon farming industry explained that:
- natural stocks of smaller oily fish could no longer support the ever-growing demand from the international farmed salmon industry
- more alternative omega-3-rich low small oily fish/high vegetable oil and plant protein feeds were being developed
- although the average omega-3 content of farmed Atlantic salmon had halved, it was still very high, and still higher than that of wild Atlantic salmon
(i) Another reason (not mentioned by the farmed salmon industry) to change the recipe for salmon feed from 80% small oily fish to a low small oily fish/high vegetable oil/high plant protein mix may be that the small oily fish are chemically contaminated and this contamination is ending up, dangerously concentrated, in the farmed salmon.
(ii) Salmon’s famed rich content of omega-3 fatty acids is more a marketing ploy than a matter of nutrition. Its rich content of omega-3 is genuine (even after the 50% reduction) but most of it not the form of omega-3 (‘triply essential’ alpha-linolenic acid) that can bring significant health benefits to humans. Atlantic salmon contains a little omega-6 (28%) and lots of omega-3 (72%), but the vast majority of the omega-3 (93%) is ‘derivative’ (either eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA)). If I were looking to increase my consumption of essential fatty acids I would not consider salmon – wild or farmed – as a good source.
1 (17329) Nick Anderson. Green Health Watch Magazine 51 11.12.2016
(17627) Nick Anderson. Green Health Watch 22.12.2018