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Perspective: Farming Fish Oils

last modified Aug 13, 2015 11:56 AM
Most people know that oily fish are good for you; the omega-3 fish oils which they contain have been shown to have numerous health benefits, not least in keeping your heart healthy. Yet do you know where those ‘fish’ oils come from?
Perspective: Farming Fish Oils


by Joanna Wolstenholme, Communications intern

So-called oily fish, such as salmon, are not able to make omega 3 fatty acids themselves, and instead accumulate them from their diet. The only organisms that are able to make these important fatty acids are some types of algae, which are eaten by smaller fish, which are then in turn eaten by salmon – so the term ‘fish oil’ is a bit of a misnomer! However, now that a great deal of salmon is farmed, where does this supply of omega-3 rich salmon food come from?

Currently, in order to ensure that farmed salmon contain the omega-3s which they are promoted for, fish farmers have to feed the salmon pelleted smaller fish, such as anchovies. These fish pellets are needed at a rate of four kilos of wild-caught feeder fish to produce the fish oil to make one kilo of salmon – which means the supposedly sustainable option of farmed fish is not so sustainable after all. Whilst fish farming reduces pressure on the wild stocks of the fish in question, it just shifts these pressures to elsewhere in the food chain – and these pressures are looking severe. By 2006, salmon aquaculture was consuming some 80 percent of the world’s fish oil and still growing at a rate of 8 to 10 percent per year, yet the populations of anchovies, menhaden and mackerel that provide the main source of fish oils are depleting fast. Fortunately this threat has been recognised, and sustainable alternative sources of fish oils are in various stages of development.

Johnathon Napier and his team at Rothamsted Research have engineered the metabolic pathway for the production of omega-3 fatty acids from algae into an oilseed plant, Camelina sativa. This work has been ongoing for 15 years now, however things are starting to look very promising. A few weeks ago, the first year field trial results were released, showing “clear evidence” that the crop produced “useful quantities” of fish oils without any negative effects on yields. This is exciting news, but the crop will still need to undergo several more years of field trials before it can start the process of getting onto the market. Even then, Napier says it “It probably makes more sense to think long-term about growing these crops in North or South America, in countries which have large aquaculture industries, such as Canada or Chile”, thanks to the current impasse on the growth of GMOs in the EU.

A different approach has been taken by Dupont, in collaboration with AquaChile; they have developed a genetically engineered form of yeast which is able to produce omega-3 fatty acids. This yeast is already being fed to its farmed fish in cages in the North Atlantic, which reduces the quantity of wild-caught fish required - from a ratio of 4 kilos of wild fish to 1 kilo of salmon to 1:1 or lower. They have branded this salmon ‘Verlasso’, marketing it as being "harmoniously farmed", in an approach that is backed by the WWF. However, Whole Foods Market – the US's most important retailer of organic, natural or sustainable foods – won't carry Verlasso salmon. As well as the use of antibiotics by Verlasso (which Verlasso say is lower than in other fish farms), and the fact that they are grown in the Pacific, rather than American waters, Whole Foods are unwilling to stock products which use GMOs. Rather than coming from the company itself, this aversion to GM is customer driven; they know their customer base is more likely to buy non-GMO products, so why stock poorly selling GMOs?

This story, like many others, is a warning of the need to shift public opinion on GMOs. Big supermarkets will only stock GMOs if they know their customers will buy them, and politicians will only legislate to allow the production of GMOs if they know their voters will not cast them out for it. So whilst we may have solutions to the issue of over-fishing for omega-3s, they will only really start to make a difference if, and hopefully when, public opinion on GMOs becomes more favourable.