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Photo: fiskeri.no.Photo: fiskeri.no

Feed resources

01.01.2014 // The strategy for an environmentally sustainable Norwegian aquaculture industry states that the raw materials for farmed fish feed shall originate from sustainably managed stocks, thereby avoiding further depletion of marine resources.

The most important measure for achieving this goal is to effectively counter illegal, unregulated and unreported fishing (IUU fishing). Norway plays an active role in efforts to counter IUU fishing at international level. Through the UN Food and Agriculture Organisation (FAO), we have gained general acceptance for the need for a global Port State Control agreement and the FAO has developed guidelines to limit discards and unwanted by-catches. The FAO’s Code of Conduct for Responsible Fisheries is an established global standard for good management and one that provides the basis for determining whether fisheries are being sustainably managed.

Feed from sustainable managed fish stocks

Measures are currently under consideration aimed at ensuring that the fish feed used in the Norwegian aquaculture industry contains only fish meal and oil produced from sustainably managed stocks. This work is ongoing and at present it is too early to say what it will entail. In the longer term, other sources of marine oil and proteins should also be utilized, and the increased use of fish by-products for feed production should be encouraged. Increased channeling of by-catches and of by-products and trimmings from fisheries and aquaculture into fish feed may be complementary to and reinforce existing efforts to improve aquaculture sustainability.

Of the global production of fish meal (about 4.8 million tonnes), approximately 65% is utilized in aquaculture production while the remainder is used in the production of feed for terrestrial animals, especially pigs, chickens and pets. Of the global production of fish oil (about 1 million tonnes), approximately 83% goes to aquaculture production while the remainder is used in foods for human consumption and technological uses.

Optimised composition and digestibility of the feed

There has been steady growth in the Norwegian aquaculture industry in the past 30 years. However, the increase in the consumption of fish feed is lower than the growth seen in production within the aquaculture industry, which can be explained by optimised composition and digestibility of the feed. In combination with improved feeding systems, this optimisation has contributed to a 15-20% reduction in the feed factor.

Farmed Atlantic salmon have traditionally been fed diets containing fish oil and fish meal, resulting in a highly nutritious fillet containing very high levels of marine omega-3 fatty acids, vitamin D, selenium and vitamin E, in addition to being an excellent protein source. However, to ensure sustainability of fish feeds and fish farming, alternative plant proteins and vegetable oils are increasingly being used in aquafeeds.

Feed with plant protein and vegetable oil

Vegetable oils are devoid of marine omega-3 fatty acids (EPA, DPA and DHA), while the levels of omega-6 fatty acids are usually high, resulting in a lowered omega-3/omega-6 ratio and reduced levels of marine omega-3 fatty acids in fish fillets. Further, when the inclusion of fish oil and fish meal decreases in aquafeeds, the dietary content of other nutrients associated with fish raw material ingredients, such as vitamin D, selenium and B-vitamins, will naturally decrease. For vitamin D and selenium this will be reflected in the fillet, whereas the fillet composition of vitamin A and protein is not altered by changes in dietary levels. Consequently, there is a net production of high quality marine protein when farmed fish are fed plant ingredients.

Importantly, even though the levels of marine omega-3 fatty acids are reduced in Atlantic salmon fed with plant protein and vegetable oil, it will still be a very good source of marine omega-3 fatty acids. 

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