Ten lochs across Scotland have been polluted by a toxic pesticide used by fish farms to control fungus, parasites and disease.

Figures released under freedom of information law reveal that more than 22 tonnes of formaldehyde, which causes cancer and is used as an embalming fluid, have been poured into cages to disinfect salmon over nine months in 2019.

The lochs affected include Loch Ness southwest of Inverness, Loch Sheil at Glenfinnan, Loch Lochy near Spean Bridge, and others in Sutherland, Wester Ross, Argyll and the Isle of Mull.

Documents released by the government’s Scottish Environment Protection Agency (Sepa) show that it has been investigating claims that heavy use of formaldehyde at Loch Tralaig in Argyll has damaged wildlife and left the loch “stinking”. The claims are denied by the local fish farm.

Campaigners fear that the chemical could harm fish, birds and mammals, as well as endanger human health. But the fish farming industry says that it breaks down quickly in water and is safe for the environment.

More toxic pesticides to be used by salmon farmers

Formaldehyde is a colourless, strong-smelling gas used in a liquid solution called formalin to treat farmed salmon in freshwater lochs. Sepa, which authorises its use, says that uncontrolled releases “have the potential to cause significant harm to the environment”.

The chemical was classified as a human carcinogen by the UK government in 2016. It has been famously used by the artist, Damien Hirst, to preserve dead animals such as cows, lambs and sharks.

New data released by Sepa disclosed that a total 22.4 tonnes of formaldehyde were used by 12 fish farms on 29 occasions between April and December 2019. Seven companies were given permission to apply the chemical, with the vast majority – 19.6 tonnes – being used by Norwegian-owned Mowi, formerly known as Marine Harvest.

At one loch – Loch Lochy, near Spean Bridge – Mowi used 11 tonnes of formaldehyde – far more than elsewhere. The company poured 3.2 tonnes into fish cages at nearby Loch Arkaig, 2.8 tonnes at Loch Sheil in Glenfinnan and 2.2 tones at Camas na Mult on Loch Ness.

Lochs polluted by formaldehyde

LochCompanyTonnes of formaldehyde used April-Dec 2019
Loch Lochy, LochaberMowi11
Loch Arkaig, LochaberMowi3.2
Loch Sheil, HighlandMowi2.8
Loch Ness, HighlandMowi2.2
Loch Tralaig, ArgyllKames Fish Farming1.4
Loch Avich, ArgyllKames Fish Farming0.79
Loch Garry, LochaberMowi0.41
Loch Shin, SutherlandCooke Aquaculture, Migdale Smolt0.36
Loch Frisa, Isle of MullScottish Sea Farms0.15
Loch Damph, Wester RossThe Scottish Salmon Company, Torridon Smolts0.08
Total22.4
source: Scottish Environment Protection Agency

The Ferret reported in June 2019 that Mowi had previously used 50.7 tonnes of formaldehyde at fish farms on four lochs between May 2017 and September 2018. An “accidental overdose” killed 1,343 fish at Glenfinnan salmon farm on Loch Shiel in October 2017.

Campaigners point out that 184 fish farms have permission to use formaldehyde and are calling for a ban. “Instead of blindly permitting salmon farming companies to discharge cancer-causing chemicals in pristine lochs, Sepa should revoke all licences to use formaldehyde,” said Don Staniford from Scottish Salmon Watch.

“At the very least there must be a public register of all toxic chemicals, not to mention public consultation. Sepa must come clean on the use of formaldehyde on salmon farms.”

Staniford, who obtained the data and documents from Sepa in response to a freedom of information request, claimed that the official figures were “just the tip of the iceberg”. He said there were at least 19 instances since 2017 in which fish farms told the Scottish Government’s Fish Health Inspectorate about using formaldehyde, but didn’t seem to have informed Sepa.

The Scottish Greens pointed out that it had been 18 months since the Scottish Parliament published a report on salmon farming concluding that maintaining the regulatory status quo was not an option. “There has been very little progress so far, and reports like this only add to the very valid concerns in local communities,” said the party’s environmental spokesperson, Mark Ruskell MSP.

“Releases of such large quantities of chemicals into the ecosystem need to be addressed as a matter of urgency. Much more needs to be done to reduce environmental impact, improve animal welfare, and have greater transparency over the chemicals and medicines.”

On 20 May Ruskell wrote to the Scottish environment minister, Roseanna Cunningham, saying he was “deeply concerned” about a proposed trial of another fish farm pesticide branded as Ectosan, used to kill sea lice. The Ferret reported in March that the active ingredient was imidacloprid, which is a neonicotinoid chemical blamed for harming bees.

We also revealed in April that Sepa had relaxed rules on the use of two other anti-lice pesticides by the fish farming industry because of the coronavirus emergency. Sepa insisted that this was necessary to help companies cope with staff shortages and social distancing, but environmentalists feared wildlife could be harmed as a result.

Pesticide blamed for ‘dead’ loch in Argyll

Emails released by Sepa included a complaint from an unnamed resident about the use of formaldehyde at Loch Tralaig, near the village of Melfort to the south of Oban in Argyll. In July 2019 the loch was claimed to be “stinking” and “dead” without any of its usual wildlife such as fish, otters, eagles and ospreys.

An “environmental event report” by Sepa described the complainant as “very angry and frustrated re perceived impact on loch and lack of action from Sepa”. There had been repeated use of formaldehyde within authorised limits in 2018-19 to treat a “fungal outbreak”, said an email from a Sepa official in September 2019.

In November Sepa launched an investigation into the use of formaldehyde at Loch Tralaig by Kames Fish Farming company. Sepa told The Ferret that the investigation was still “ongoing”.

The Coastal Communities Network, which brings together sixteen groups concerned about the marine environment in Scotland, was aware of the alleged problems at Loch Tralaig. “We are hearing shocking accounts from people who live alongside a freshwater loch that contains a fish farm,” said the network’s John Aitchison.

“They report that the loch no longer supports wild trout, and that otters and ospreys have abandoned it. This loss coincides with them seeing unusually large amounts of formaldehyde being tipped into the water by the fish farm.”

Aitchison was also concerned that the official records on formaldehyde use seemed inconsistent. “Formaldehyde is just one of the toxic chemicals used by Scotland’s fish farmers to treat diseases and parasites,” he added.

“They are all discharged into the water, where their cumulative impacts are largely unknown. We urge Sepa to investigate the reasons for the loss of wildlife at this loch, and to show that the reported level of formaldehyde use nationwide matches the amount actually being dumped into the water.”

An anti-fish farming campaigner based in mid-Argyll, Ewan Kennedy, said: “Formaldehyde is a deadly, cancer causing, chemical that until recently was considered too dangerous for use as a medicine. Its use as a medicine in fish farming is highly controversial.

“Apparently this was the first time the company used it in Argyll, which must raise the question why there was no environmental assessment of the likely impacts on the native fish, the creatures that predate on them and even the local residents.”

The Scottish Environment Protection Agency emphasised that it wanted to reduce pesticide use by fish farms. “Fish farm operators require an authorisation from us before they can use formalin to treat their fish,” said the agency’s head of ecology, Peter Pollard.

“When granting authorisation, we place strict limits on the quantities that can be used. The limits are set to keep discharges to levels that the receiving rivers and lochs can accommodate without compromising environmental quality standards.

He added: “We routinely carry out audits of farms authorised to use formalin to check that operators are complying with the limits. We share an aspiration with the sector for a future where fish farmers are increasingly less reliant on chemical and medicine based controls.”

Scottish fish farms using cancer-linked embalming fluid as disinfectant

According to Sepa, formaldehyde was used to treat a range of conditions including white spot and bacterial gill disease. It was “readily biodegradable” so quantities didn’t accumulate over time in lochs.

Responding to the suggestion that official figures underestimated the use of formaldehyde, a Sepa spokesperson said: “We are happy to review information sent to us about alleged discrepancies and will investigate as required.”

The Scottish Salmon Producers Organisation (SSPO), which represents fish farming companies, defended use of the chemical. “Formaldehyde is an active ingredient that appears in dilute form in a licensed medicine fully approved for use by Sepa,” said a spokesperson for the organisation.

“Such medicines are used in freshwater farms to protect young salmon from water-borne challenges. Formaldehyde itself is a naturally occurring compound that swiftly breaks down in water and is therefore safe to use for both fish and the environment.

“Fish farmers are fully trained in the correct usage of any medicinal treatment used to protect fish health and welfare.”

Mowi Scotland supported SSPO’s statement and declined to comment itself. The company’s spokesperson, Ian Roberts, previously confirmed that about 1,300 juvenile salmon had died because of a “human error” with formaldehyde at Loch Shiel in October 2017.

He told The Ferret in June 2019: “Formalin is used to protect small salmon in our freshwater farms from water-borne bacteria. Safe use of the product is licensed by Sepa under the controlled activities regulations (CAR), following Sepa’s established environmental risk assessment that ensures product application meets environmental quality standards.”

Kames Fish Farming, which has its headquarters at Kilmelford by Loch Melfort in Argyll, stressed that formalin was used “in dilute form” and swiftly broke down in water. “The use of formalin in smolt (young salmon) farming is based on science and is closely regulated by Sepa,” said the company’s managing director, Stuart Cannon.

“Use at our farm has always been done in accordance with these strict regulations, and within the terms of our CAR license issued by Sepa. We did have one complaint about use of formalin on our farm in 2019.”

He added: “We collaborated fully with the following Sepa investigation, which concluded that all use at our farm is in accordance with regulations. Later inspections by Marine Scotland and Health and Safety Executive authorities have also concluded that we are, and have always been, in compliance with all regulations.”

Cannon insisted that the company had the greatest respect for Loch Tralaig and the natural habitats and ecosystem surrounding the fish farm. “We depend on a healthy loch to be able to farm our fish,” he said.

“Damaging the loch would not only be ethically wrong, it would also impact our own business negatively. We have conducted our operations in Loch Tralaig for 35 years, and there is no scientific evidence that suggests we have done any damage to the loch.”

The documents released by the Scottish Environment Protection Agency

200306 F0191629 Formaldehyde (Text)

F0190275 Sites (Text)

Release Q2 Q4 Q7 (Text)

Release Q6 (Text)

Photo of Loch Ness thanks to iStock/Tiago Fernandez. This story was published in tandem with the Sunday National.

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SEPA is not fit fpr purpose, and fish farms should be in closed containment, either in water or on shore. Time for the fish farm operators to move forward and stop the pollution that they produce.

The fast buck will over rule all considerations for the environment. Scotland’s intrinsic beauty is being sold of to foreign interests with no consideration for the future. Our grand children will view with horror the wasteland and wastewater they inherit and will never forgive those who should have protected it.

Usually, when people say ‘there is no scientific evidence’, what it really means is that the necessary studies have NOT been carried out (usually due to a lack of funding of such activities). Call me cynical, but, as a scientist, I know that is the way the process works these days.

George Richardson

Poor journalism .One side of the story backed by well known and recognised extremist with huge chip on his shoulder . Please don’t believe this rubbish .

Cathel Hutchison

Hardly a convicing or credible comment without evidence to rebut.

Can you please direct the above to Fishery management Scotland for a response please