The use of drugs at salmon farms in Scotland has risen more than 50 times over the last six years, according to information released by the Scottish Environment Protection Agency (Sepa).
The amount of antibiotics given to caged salmon to combat diseases at over 50 farms around Argyll, the highlands and islands has risen from 147 kilograms in 2016 to 7,476 kilograms in 2021.
Campaigners have warned that the growing use of antibiotics could make diseases harder to treat and endanger human health. They urged fish farm companies to end their “completely unsustainable” drug dependency and called for tougher regulation of salmon farms.
Companies stressed that antibiotics were used responsibly to protect fish health and welfare. Accusations suggesting irresponsible use based on annual comparisons were “intentionally misleading”, said one.
The elevated use of antibiotics helps viruses, bacteria, fungi and parasites develop resistance, rendering them more difficult to combat. Known as antimicrobial resistance, it is regarded by health authorities as one of the biggest global threats to public health.
One major salmon farming firm, Scottish Sea Farms, claimed to have eliminated antibiotic use in 2020 and 2021. It was important “that antibiotic use is minimised and only used when absolutely essential,” the company said.
But a spreadsheet released by Sepa under freedom of information law reveals that the use of two antibiotics by five other salmon farming companies across Scotland has risen sharply since 2016. Altogether they used over 16.5 tonnes of Aquatet and Florocol over six years to treat fish infections.
Rise in the use of antibiotics by salmon farms
By far the biggest user was the Norwegian seafood giant, Mowi, which was responsible for 88 per cent (14.5 tonnes) of all antibiotic use at salmon farms in Scotland since 2016. The chemicals have been applied at more than 30 farms, with some being treated in three, four or five years.
The largest reported annual use of Aquatet was 3,674 kilograms at Bagh Dail nan Ceann salmon farm in Argyll in 2020, with other major doses in 2021 at Macleans Nose, Ardintoul in Highland and Tabhaigh and Erisort in Eilean Siar. The biggest annual dose of Florocol — 830.5 kilograms — was at Loch Duich in Highland during 2019.
Four of the Mowi farms recording antibiotic use — Invasion Bay, Portnalong, Isle of Ewe and Balmeanach Bay in Highland — have reportedly been classified as organic. Others have been certified as “farmed responsibly” by the international Aquaculture Stewardship Council.
Mowi farms have been hit by at least six salmon diseases, which can be treated with antibiotics. The company’s financial report for the fourth quarter of 2021 mentioned gill disease, heart disease and a bacterial infection, all of which can be lethal.
Another of the companies reporting antibiotic use 17 times between 2017 and 2020 was Grieg Seafood Shetland. In December 2021 it was bought by Scottish Sea Farms, which is seeking to minimise antibiotic use.
“Mowi should check itself into rehab to curb its drug dependency. Shoppers in Sainsbury’s and Tesco should say no to drugs by boycotting Mowi salmon.”
Staniford called on Sepa to start testing for antibiotic contamination of sediments under salmon farms and the government’s Food Standards Scotland to investigate antibiotic resistance of Scottish salmon.
The Scottish Greens called for tougher regulation of salmon farms. “This soaring use of antibiotics in industrial salmon farming is deeply troubling as a symptom of the levels of infections among the fish stock,” said the party’s rural affairs spokesperson Ariane Burgess MSP.
“Antibiotic resistance is built up over time, so this is a completely unsustainable approach. We know that long overdue regulatory change of this industry is coming, but this shows that if it is going to become sustainable those regulations must come with much stronger environmental standards.”
The food campaign group, Feedback, said it was “worrying” that drug use at fish farms was rising. “Routine use of antimicrobials in aquaculture is unnecessary and an indicator for poor animal welfare on farms,” argued head of campaigns, Natasha Hurley.
“It undermines sustainable food production, threatens the wider ecosystem and fuels the spread of drug-resistant superbugs, which pose one of the biggest threats to public health this century.”
Mowi accused campaigners of misrepresenting antibiotic use. “High-quality Scottish salmon requires little antibiotics compared to other farmed animal proteins available to consumers, and our company publicly reports annual use for anyone to read,” said the company’s Scottish spokesperson, Ian Roberts.
“Accusations that suggest irresponsible use based on comparisons from one year to the next are intentionally misleading and show little understanding of animal care.”
He pointed out that licensed medicines were “occasionally and responsibly” used under the full care of veterinarians to protect the health of fish. “We will continue to act quickly to alleviate any stress our salmon may face,” he told The Ferret.
“Changing ocean conditions are providing sea farmers and their fish new challenges to overcome, and we are committed to keeping our fish healthy and safe.”
Scottish Sea Farms emphasised its commitment to reduce, but not rule out, the use of antibiotics. “While it’s not our business to comment on another producer’s performance, particularly having only acquired Grieg Seafood Hjaltland UK in December of last year, what we can say is that, owing to diligent fish husbandry and the proactive use of vaccines, the company achieved zero antibiotic usage in 2021,” said head of veterinary services, Ronnie Soutar.
“This is a position that aligns closely with our own approach and means that all stock across our combined estate are free of antibiotic treatment.”
Soutar added: “That said, as with any livestock farmer, the conditions in which we operate continue to change, and antibiotics, used in accordance with our stringent antimicrobial resistance practices, remain an important option should we consider it in the best interests of fish welfare.”
In May 2021 Scottish Sea Farms announced that it had eliminated antibiotic use in all its farms in 2020. It highlighted how important it was “that antibiotic use is minimised and only used when absolutely essential.”
The company described antimicrobial resistance as “one of the biggest issues facing global health today”. Though resistance could occur naturally “it’s thought that over-reliance on antibiotics in human and animal health could be adding to the problem, with medical and veterinary professionals around the world tasked with reducing usage wherever possible,” it said.
The Ferret reported in 2018 that pesticides — also used at salmon farms to kill sea lice — had been found to be harming marine wildlife. A survey by the Scottish Environment Protection Agency had found widespread contamination around eight fish farms.