Fish farming industry bids to relax limits on toxic pesticide

Emamectin benzoate
Fish farm in Loch Ainort © Richard Dorrell

The multinational salmon farming industry has been pushing behind the scenes for environmental limits on a toxic pesticide to be 100 times weaker than government regulators recommend. 

The Ferret can reveal that the pesticide’s US manufacturer, Merck, and the Scottish Salmon Producers’ Organisation (SSPO) funded an unpublished study arguing that wildlife in sea lochs could withstand high concentrations of the pesticide.

The industry’s move to relax the limits has been condemned as “beyond belief” by community groups, while environmentalists have urged fish farmers to protect wildlife by ceasing to use the pesticide. But the industry insists that it has confidence in its science.

Scottish ministers will ultimately decide the issue. They are being urged by campaigners not to give in to industry pressure as they have done before – and to back the tough new limits.

The pesticide is called emamectin benzoate and is marketed as Slice by the £33 billion Merck pharmaceutical company which is headquartered in New Jersey. It is widely used by fish farmers around Scotland’s coasts to kill sea lice that plague caged salmon.

Emamectin benzoate

A 2016 study by the Scottish Association for Marine Science warned that emamectin was harming crabs, lobsters and other crustaceans around fish farms. As a result the Scottish Environment Protection Agency (Sepa) proposed a ban.

But in a series of investigations in 2017 and 2018 The Ferret reported that both Sepa and the Scottish Government secretly bowed to pressure from SSPO and Merck – and withdrew the proposed ban. Critics dubbed the affair “Slicegate”.

Then a 2018 survey by Sepa around eight fish farms in Shetland found emamectin had spread more widely than previously thought. “The existing approaches do not adequately protect marine life,” Sepa concluded, and introduced interim restrictions.

Sepa also asked the UK Technical Advisory Group (UKTAG), which brings together scientists from all the UK’s environmental regulators, to recommend safety limits for the pesticide. On 24 May it made its findings available for consultation.

UKTAG reports reveal that scientists had received and assessed a study by consultants, WCA Environment, funded by Merck’s UK division, MSD Animal Health, and SSPO. The study has not been published.

According to UKTAG, the industry study concluded that environmental quality standards for emamectin benzoate in seabed sediment should be between 1,290 and 2,580 nanograms per kilogram. That’s more than 50 or 100 times higher that the 23.5 nanograms per kilogram proposed by UKTAG.

UKTAG scientists criticised the “variability” of the industry’s data from around 19 fish farms on the west coast and islands. As a result the study was “questionable” and “inconclusive”, UKTAG said.

Concerned coastal communities

The Coastal Communities Network, which brings together 16 groups around Scotland’s shores, is worried that emamectin benzoate is harming shellfish. It is calling on Scottish ministers to resist industry lobbying to weaken environmental limits.

“It seems beyond belief that a pesticide company can lobby a regulator to be lenient when setting the standards that will govern the use of its products, based on data and analysis which it refuses to make public,” said the network’s fish farming spokesperson, John Aitchison.

“It is hard to understand how the SSPO can justify funding this study while claiming that its members are using the sea sustainably.”

He added: “Surely the industry must see how irresponsible it is to argue that it’s safe to discharge high levels of a persistent pesticide into the sea where many jobs depend on catching crabs, lobsters and prawns?

“Surely it must also see that this destroys the credibility of its PR and advertising, that so often trade on fish farmers rearing salmon in Scotland’s pristine seas?”

Aitchison argued that ministers’ ultimate decision on safe levels for emamectin would be “the acid test” of whether fish farming can expand without harming the environment.

“Behind the scenes the fish farmers and pesticide manufacturers will be doing their best to persuade Scotland’s politicians to adopt their suggestions,” he warned.

Widespread criticism

The Scottish Greens also pressed ministers not to bow to industry pressure. “Emamectin is a toxic pesticide which has been shown to devastate marine life,” said the party’s environment spokesperson, Mark Ruskell MSP.

“Sepa previously believed there was a case for an outright ban on its use, so at the very least ministers must back the stringent controls now recommended by experts, and resist the inevitable pressure from industry lobbyists and their dubious, unpublished research.”

The National Trust for Scotland pointed to mounting evidence that toxins used by fish farmers were seriously damaging wild crustaceans, including commercially important crabs and prawns.

“We are delighted to see that UKTAG has followed the lead of Sepa in recommending that the levels of these toxins in the environment need to be dramatically reduced,” said the trust’s senior nature conservation adviser, Richard Luxmoore.

“The aquaculture industry is recommending hugely elevated levels similar to those that we already know are killing marine wildlife. Accepting the industry’s assessment of safe levels for these chemicals would be like accepting the fox’s advice on chicken farm security.”

Scottish Salmon Watch claimed emamectin was a “serial killer” of shellfish. “Sepa must ban emamectin as they proposed back in 2016 before the industry, Scottish Government and chemical giant Merck successfully lobbied to delay, deny and distract,” said the campaign group’s Don Staniford. “No ifs and buts and no more delays.”

The wild fish group, Salmon and Trout Conservation Scotland, urged the industry to accept that it must stop using emamectin. “It has a choice now,” said the group’s solicitor, Guy Linley-Adams.

“Keep fighting this confidential rear-guard action, trying desperately to hang onto Slice. Or it can find another way to grow farmed salmon.”

Read the full article Fish farming industry bids to relax limits on toxic pesticide at The Ferret.

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