Farmed salmon were given overdose of toxic chemical

SALMON farming is under threat from an epidemic of sea lice and the use of toxic chemicals to control them, say campaigners.

In a bid to kill the lice, which feed on captive fish raised in cages off the coast of Scotland, salmon have been given an overdose of chemicals which can also harm humans.

Problems occurred at two sites run by the Scottish Salmon Company, which boasts of selling ‘Scotland’s finest sea loch fresh salmon’. the chemical emamectin benzoate, used to eradicate the lice, is a potential risk to human health because it interferes with nerve impulses in the body, should residues in the fish end up on dinner plates.

the problem occurred in February last year at Vacasay and taranaish, both in Loch roag, off the Isle of Lewis, in the Outer hebrides. three samples of salmon at these Scottish Salmon Company sites had levels of emamectin above permitted levels.

But the fish were not destroyed. Instead they were harvested in November, presumably to be sold at Christmas, although the company refused to give any details.

the Scottish government insists the delay between the overdose and the fish being eaten means any residues would have fallen well below official safety levels.

the chemical is also harmful to other sea life, such as shellfish and lobsters. the Global Alliance Against Industrial Aquaculture, which carried out the investigation, said the episode will tarnish the reputation of the industry. Don Staniford from the GAAIA said: ‘Scottish salmon is farmed and dangerous. the alarming rise in emamectin benzoate use is now becoming a public health issue.’

the GAAIA said there was good evidence that high emamectin levels in the waters around salmon farm cages was harming marine life. A report published in the Scottish Aquaculture research Forum revealed lethal impacts on shellfish from the use of emamectin. earlier this month, the Scottish environment Protection Agency said it was reviewing all fish farming licences permitting the use of the chemical, with a view to tightening controls.

the Scottish Salmon Company exports a lot of its fish and mainly supplies restaurants. It said: ‘We take the health and welfare of our fish very seriously. In early 2016 there was an isolated incident during the growing cycle. Samples were taken during routine industry testing which showed marginally higher than threshold levels of emamectin. this took place over a year ago, additional checks were immediately put in place to ensure no further incidences and we continue to work in line with industry best practice.’

the company issued trading figures in February which admitted difficulties in coping with industry-wide ‘biological challenges and mortalities’, specifically sea lice.

Salmon is the UK’s fourth largest export in terms of food and drink behind whisky, beer and chocolate with sales overseas of almost £600million a year.

‘Public health issue’