Eco fish food harnesses essence of worm
by Lewis Smith
July 19 2010 Lewis Smith
Ragworm (Nereis virens)
Anglers, as anyone who reads children’s comics will know, have used worms to catch fish for years. Now the humble worm is being taken up by fish farmers to make aquaculture more sustainable.
By using the worms as a key ingredient in a specially designed fish food an experimental trout farm in Wales has found a way to feed its stock without depleting marine fish stocks.
The novel feed, using ‘essence of worm’, has gone on sale as a sustainable alternative to fish food that is made from wild fish. It is estimated that for every 1tonne of fish produced by aquafarms, at least 1.5 tonnes of fish had to be hauled out of the sea and used to feed their farmed cousins. The loss of so many fish from the seas simply to feed farmed varieties is considered by many marine campaigners to be an unsustainable absurdity.
But the experimental scheme farms worms on an industrial scale and – taking the ‘fish’ out of ‘fishmeal’ - uses them rather than fish to feed farmed stock. Moreover, it is a technique that can be adopted around the world using worms native to each region.
Tony Smith, of Dragon Feeds in Port Talbot, started by breeding a large type of ragworm, the polychaete species Nereis virens, for the sports fishing industry but realised they had great potential for the aquaculture sector.
At present the company produces up to 6,000 tonnes of feed using worms each year grown in tanks at Port Talbot and Pendine. It’s development has been supported by European grant money.
Tanks used to grow ragworms
Alongside the use of worms as a key ingredient, his team developed a technique to combine amino acids to protein which allows fish to digest the feed efficiently. So efficiently, in fact, that they produce significantly less waste material.
Kit Smith, of Dragon Feeds, said that the use of tiny quantities of liquidised ragworm in the new feed has the effect of making farmed trout eat consistently, even in cold conditions that would normally inhibit their appetites. The result is they grow faster.
"We’ve replaced fishmeal with a little bit of know-how with the amino acids and then we’ve gone back to the worm," said Mr Smith. "We add just a little bit of essence of worm which triggers something within the fish that makes it feel as if it’s living in the wild. The introduction of farmed polychaetes into the feed has acted as a significant attractant, making the feed more palatable to fish."
He added: "Dragon Feeds has developed a viable and fully sustainable alternative to fishmeal."
Rainbow trout grown using sustainable ragworm
The worms are fed on the left over bits of fish – head, guts, skin and bones – from a processor in the South West that would otherwise be thrown away. The voracious but unfussy worms could, said Mr Smith, equally well be fed on other waste materials such as from the chicken industry.
Small quantities of recovered fish oil are also derived from the waste material and are used as an ingredient but Mr Smith expected this to be replaced in about two years by algae containing a pure form of Omega 3. Other ingredients used by Dragon Feeds include responsibly sourced soya, wheat and pea protein.
Dr Andrew Jackson, welcomed the development of the feed and the use of the worms which he said “sounds like a good idea” that “everyone is watching with interest”. He said Iffo is trying to encourage the development of new, efficient and sustainable sources of fish food to supply the burgeoning aquaculture sector.
Dr Jackson added that the use of waste fish products, such as heads, is already used in the production of 23 per cent of the world’s fish meal. However, he questioned how efficient it is to feed the waste fish to the worms rather than giving it directly to cultivated stock.
The feed has been on the market for nine months and one of its customers is Steve Wood, joint owner of Vicar’s Mill Trout Farm in Dyfed, who also used it during the development stage. He was happy with the feed’s performance, describing it as “top notch”, and said environmental concerns are one of his prime reasons for using it: “We can’t keep taking from the seas to produce less than you take.”
Estimated figures suggest that in 2006 the global aquaculture secture used 3.7 million tonnes of fishmeal and 835,000 tonnes of fishoil. They represented the equivalent of 16.6 million tonnes of fish such as anchovies and sardines.
The aquaculture sector is growing rapidly and is expanding by about 10 per cent each year, with much of the growth and some of the least sustainable use of fishmeal in China.
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1 Responses to "Eco fish food harnesses essence of worm"
Marc Says:
This is an innovative approach to aquaculture, probably one of many ideas that will appear as fish farms are pressured to use fewer wild fish. What is Dr. Jackson's affiliation? Has the 23% waste fish product statistic been published?
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