MORE than one-third of deaths in some Atlantic salmon are caused by sea lice found largely in stocks of farmed fish, new research has claimed.
An unexpectedly large number of free-ranging salmon are being killed by the parasitic lice in European waters every year, a major international study involving experts in Scotland has found.
The study, published today in the biological research journal Proceedings of the Royal Society B and partly carried out by scientists at St Andrews University, is claimed to be the first evidence of the full impact of lice on salmon mortality levels.
The aquaculture industry has been urged to protect the health of its own stocks in order to reduce the threat to wild fish.
Professor Christopher Todd, of the Scottish Oceans Institute at St Andrews, was part of an international group which found sea lice to be responsible for 39% of the deaths among salmon in the north-east Atlantic.
He said: "For the first time we can effectively place a reliable value on the predicted mortality loss of free-ranging salmon subject to infection from this parasite. This high percent mortality attributable to sea lice was unexpected.
"The salmon aquaculture industry has long placed a high priority on controlling sea lice on their captive salmon – but these results do emphasise the need for the industry to not only maintain the health of their own stocks, but also to minimise the risk of cross-infection of wild fish."
Sea lice are natural parasites of wild salmon and also present the salmon aquaculture industry with major challenges as the parasite can debilitate or kill the salmon host.
Producers insist 95% of salmon will die naturally at sea during their ocean migration, but over the past 20 years controversy has surrounded the contribution of sea lice parasites to mortality rates.
Why are you making commenting on The Herald only available to subscribers?
It should have been a safe space for informed debate, somewhere for readers to discuss issues around the biggest stories of the day, but all too often the below the line comments on most websites have become bogged down by off-topic discussions and abuse.
heraldscotland.com is tackling this problem by allowing only subscribers to comment.
We are doing this to improve the experience for our loyal readers and we believe it will reduce the ability of trolls and troublemakers, who occasionally find their way onto our site, to abuse our journalists and readers. We also hope it will help the comments section fulfil its promise as a part of Scotland's conversation with itself.
We are lucky at The Herald. We are read by an informed, educated readership who can add their knowledge and insights to our stories.
That is invaluable.
We are making the subscriber-only change to support our valued readers, who tell us they don't want the site cluttered up with irrelevant comments, untruths and abuse.
In the past, the journalist’s job was to collect and distribute information to the audience. Technology means that readers can shape a discussion. We look forward to hearing from you on heraldscotland.com
Comments & Moderation
Readers’ comments: You are personally liable for the content of any comments you upload to this website, so please act responsibly. We do not pre-moderate or monitor readers’ comments appearing on our websites, but we do post-moderate in response to complaints we receive or otherwise when a potential problem comes to our attention. You can make a complaint by using the ‘report this post’ link . We may then apply our discretion under the user terms to amend or delete comments.
Post moderation is undertaken full-time 9am-6pm on weekdays, and on a part-time basis outwith those hours.
Read the rules hereComments are closed on this article