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An environmentally-friendly way of reducing the amount of salmon lice in Norwegian aquaculture is putting lice-eating wrasse together with the salmon. A new large-scale research project will prepare for commercial aquaculture, in order to ensure an adequate supply of the lice eaters.
When it comes to eating salmon lice from large salmon, the Ballan wrasse (Labrus bergylta) is the most efficient wrasse, and it also gathers lice at lower temperatures than other species.
A total of 2 to 5 per cent of wrasse is needed in the sea cages in order to delouse the salmon, or in other words a cage containing 100,000 salmon requires 2000 to 5000 wrasse. The largest number of salmon lice found in the stomach of a single Ballan wrasse is 300, while the average is 70. |
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The Fishery and Aquaculture Industry Research Fund (FHF) is behind this heavy investment, which stretches over a three-year period and has a budget of around NOK 26 million (USD 4.5 million).
The objective is to develop the knowledge and experience that is necessary to attain a stable and predictable commercial production of the Ballan wrasse.
The wrasse are transferred to the sea cages and eat the sea lice on the farmed salmon, avoiding the need to use chemicals to delouse the salmon.
"The effort which is now commencing is unique in both a Norwegian and global context. Norway is the only salmon-producing country that is using wrasse on a large scale to combat salmon lice," says the Managing Director of the research fund, Arne E. Karlsen.
Until now mainly wild-captured wrasse has been used. However, there is a limited supply of wrasse in the wild, and an increase in the catch can pose a threat to the wild fish stocks.
The goal of the project is to cover at least 25 per cent of the requirements with farmed wrasse by 2013. |
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