New solutions for sustainably farmed fish

Sensemaking / New solutions for sustainably farmed fish

From yeast-based feed to underwater symbiosis, innovations in aquaculture could make fish-farming a leading industry in sustainable food production.  

28 Feb 2012

From yeast-based feed to underwater symbiosis, innovations in aquaculture could make fish-farming a leading industry in sustainable food production.

At current rates, there won’t always be more fish in the sea: the UN estimates that we will need to farm almost half the fish we’ll want to eat in 2020. Aquaculture production is already higher than wild-caught fish, and growing. But the challenge is producing the greatest yield without damaging marine life. A wave of innovations could make it possible.

In the US, salmon reared on a new, more sustainable diet came on sale in September 2011. The trick is a yeast-based feed which is rich in fatty acids, and so reduces by 75% the quantities of feed made from wild-caught fish which are needed. The new feed is packed with long-chain omega-3 fatty acids, a good substitute for fish oils. Normally, to produce 1kg of healthy farmed salmon, you would need to nourish them with 4kg of fish: with this diet, just one kilo is enough.

This technique, developed by commercial science company DuPont, has been implemented in AquaChile’s commercial farms in Patagonia, Chile. The partnership came out of the Salmon Aquaculture Dialogue, part of a wider project by WWF to seek out the leading innovations in sustainable aquaculture. AquaChile’s yeast-fed salmon are also reared in more spacious pens, to reduce the risk of disease and the need for antibiotics.

These developments come at a cost to the consumer, though: the fillets retail at $16.99/lb – around twice the standard price. So who’s prepared to pay? WWF hopes that a new label will win consumer confidence, and persuade them to fork out. It is establishing the Aquaculture Stewardship Council to set and oversee standards for responsible seafood farming.

But the hunt for sustainable practice is a wide one. The Research Council of Norway first looked into the future of marine fishing in 2003. Now, a new programme aims to make Norway ‘the world’s leading aquaculture nation’. One focus of the research is keeping farmed fish healthy, developing medicines and vaccines to tackle the problem of sea lice, for instance. This in turn improves the health of wild fish, as infestations of sea lice can easily spread from farms to open sea.

Another promising solution is ‘integrated multi-trophic aquaculture’, where complementary stocks are farmed in close proximity. So, nutrients excreted by farmed fish are taken up by algae, which are then eaten by shellfish. The algae can be harvested for biofuels, diversifying income for the farmer. It’s just one benefit pointed out by Dr Piers Hart, Aquaculture Policy Officer at WWF.

“Marine aquaculture gets around many environmental problems in the food system, such as conflicts over land use, chemical fertilisers and greenhouse gas emissions”, says Hart. “If we get it right from the outset, it offers a much more responsible way to feed ourselves.” – Charlotte Owen 

Photo: iStockphoto / thinkstock

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