Sunday, 18 June 2017

Salmon farmers ‘put wild fish at risk’ in fight to kill off sea lice




Use of wrasse to combat parasite threatens natural stocks, say experts 

Robin McKie, science editor
Saturday 10 June 2017 22.11 BST 

Salmon farmers have been accused of playing dirty by using fish caught in the wild to clean lice from Scottish fish farms. Marine conservation experts say that shipping tonnes of English-caught wrasse a year – to tackle lice infestations in salmon pens north of the border – is endangering natural stocks. English anglers have also warned wrasse is becoming harder and harder to find in local waters.

However, salmon farmers have rejected the charge. They say the use of wrasse as a “cleaner” fish is part of a long-term plan to replace chemicals – which are currently administered to pens to control lice infestations – with sustainable, biological controls.

Fishermen remain concerned, nevertheless. “Wrasse play a role in keeping the marine ecosystem in balance,” said David Mitchell, of the Angling Trust. “We simply do not know what will be the consequence of removing so many of them from our coastal waters.”

More than 170,000 tonnes of salmon a year are grown in Scotland at more than 200 marine farms. However, production is affected by lice infestations that cause lesions and secondary infections in the fish. Chemicals can control this but pollute water around the farms. Another solution is provided by wrasse which feed on marine insects. Many species – such as ballan and goldsinny wrasse – will eat lice that infect larger fish. As a result wild wrasse are being caught in pots and shipped to Scotland to tackle sea-lice infestations. One wrasse for every 25 salmon is used.

But this exploitation of wrasse is raising concerns. “We are very worried that a large local fishery has developed rapidly over the past couple of years – with large numbers of wrasse being taken from local waters – without proper management or any indication of its sustainability,” said Samuel Stone, of the Marine Conservation Society. “It is a real concern.”

No comments:

Post a comment

You only need to enter your comment once! Comments will appear once they have been moderated. This is so as to stop the would-be comedian who has been spamming the comments here with inane and often offensive remarks. You know who you are!

Related Posts with Thumbnails

ShareThis