- Scotland is the world’s third-largest producer of farmed Atlantic salmon (Salmo salar), after Norway and Chile.
- The industry is seeking to significantly increase production in Scotland, driven by growing export demand.
- However, it faces ethical concerns over mounting fish mortality, as well as environmental concerns about pollution, the proliferation of sea lice affecting wild salmon, and opposition from several local communities.
- Industry members acknowledge the challenge of growing salmon amid rising sea temperatures, but say Scottish salmon farms have made progress in managing sea lice and other health challenges.
ULLAPOOL, U.K. — The fish float on the surface by the dozen, their bellies pointing toward the still-dark sky of the early morning. We are peering into a cage of an intensive Atlantic salmon farm, owned by the Norwegian multinational Mowi, in Upper Loch Torridon along Scotland’s west coast. It’s September 2024.
It’s difficult to tell why these salmon died. On one carcass, a salmon louse (Lepeophtheirus salmonis) can be seen moving, but most of the fish in the pens, alive or dead, have abrasions and wounds, perhaps from treatments to eliminate lice and other parasites.
Jamie Moyes, a local activist who has been investigating salmon farms for years and accompanied Mongabay to the farm in a small dinghy, inspects the fish carcasses while collecting footage to post on his social media channels. Behind him, the lights turn on in a boat, signaling that the company workers who are sleeping there have been alerted to our presence.
“We filmed that farm a year and a half ago, and it was absolutely terrible,” Moyes said later, back on dry land, recalling a massive infestation of lice.
“The most shocking thing today was the amount of death floating on the surface,” he said. “It could easily be up to 50 dead salmon in one cage, floating on the top. There’s something wrong there.”
A few weeks later, we find out the reason for the dead fish in the farm. A monthly mortality report, published by the Scottish salmon farming industry for September 2024, revealed that the Mowi salmon farm in Torridon suffered a 6% mortality due to “gill health related” problems. Until 2021, the farm had a 2,500-metric-ton biomass capacity, and in 2022 an expansion plan was approved, adding two more cages to the 10 existing ones.
Scotland is the world’s third-largest producer of Atlantic salmon (Salmo salar), after Norway and Chile. The industry is seeking to significantly increase production there, driven by growing foreign demand. However, it faces ethical concerns over mounting fish mortality, as well as environmental concerns about pollution, the proliferation of sea lice affecting wild salmon, and opposition from several local communities.
“Mortality has risen in the region, a sort of 8-10% increase over the last decade,” Ben Hadfield, Mowi Scotland’s chief operating officer, told Mongabay. “We can’t get away from the fact that, because of warming coastal temperatures in Scotland, it has been challenging to farm fish in the sea.”
Dying fish
Mowi is the world’s leading salmon producer. In Scotland, the company produces 65,000 metric tons annually, more than a third of the national production of around 185,000 metric tons projected for 2024.
According to Scottish government data based on monthly reports provided by the industry, 17.4 million salmon died prematurely in 2023 across the country’s 210 farms, and the survival rate was 68.7% (calculated for juvenile salmon, or smolts, introduced two years earlier). Both figures are up from 3.7 million dead fish and a survival rate of 76.6% in 2018. That represents more than a quadrupling of fish deaths and an 8% decrease in survival rates over the five years.
“The mortality rate, the number of salmon that die in fish farms, is startlingly high,” Rob Edwards, a journalist with the Scottish investigative outlet The Ferret, who has been writing about salmon farming over the last 30 years, told Mongabay. “It varies year to year, but it can get up to kind of 30, 40 or even 50% of the stock [in a single farm] in bad years,” he said.
According to the industry, the recent high mortality levels are due to an increase in temperatures that brings more zooplankton, algal blooms and micro jellyfish. Respectively, these may produce gill health problems, deadly toxins and carry poison that harm the salmon. “We see species of jellyfish that are associated with Spain, France, Portugal, maybe even in the Med[iterranean], actually present in [Scottish] West Coast waters and in much higher levels, because when these species come north they generally bloom,” Hadfield told Mongabay.
Hadfield said the industry has mitigated these climate-related issues by reducing mortality from other causes via improved technology, for instance controlling salmon lice and other parasites by means of freshwater and mechanical treatments. “The level of innovation in Scottish aquaculture is extremely high,” he said.
In 2018, the Scottish parliamentary committee on the rural economy carried out a public inquiry, aiming to shed light on the farming conditions and environmental impact of salmon production. After several weeks of investigation, the committee published a report expressing concern about both the high mortality rates and the environmental impacts on local marine environments of fish waste and medicines to control parasites, and about high levels of sea lice transmission to wild populations.
The report included 65 recommendations to the Scottish government, and stated that “if the industry is to grow, the Committee considers it to be essential that it addresses and identifies solutions to the environmental and fish health challenges it faces as a priority.”
“The main finding of the report was that the status quo regarding salmon farming was not acceptable,” Edward Mountain, an MP for the Highlands and Islands region who was on the 2018 committee, told Mongabay in an email. “There needed to be more stringent regulation and inspection of the industry, as well as a review of the siting of salmon farms.”
Following the publication of the report, the salmon industry in Scotland did grow its production capacity, although not consistently its actual production due to high mortality.
“Mortality was already too high in 2018,” Rachel Mulrenan, director of the NGO WildFish in Scotland, told Mongabay. It has only increased since the inquiry came out, “and yet nothing has been done about it,” she said. “We had these strong recommendations coming from the parliament, and yet the industry continues to expand, the Government continues to support the industry.”
In May 2024, the successor to that 2018 parliamentary committee launched a follow-up inquiry to find out how the earlier recommendations had been implemented. The investigation is ongoing and the results have not yet been disclosed.
In a letter to the committee, Tavish Scott, chief executive of the industry association Salmon Scotland, disputed the findings of the original inquiry and said the industry had made progress: “Sea lice levels on salmon farms are the lowest since published data were first available,” he said. “Low lice levels are testament to the hard work of the sectors[’] farmers, veterinarians and fish health specialists, alongside the near £1 billion [$1.26 billion] of investment companies have made in the diverse range of management tools that ensure fish health and welfare since 2018.” The industry body later said in a press release that this investment helped farms reach a 98.18% survival rate in September.
The transparency of the figures about mortality and sea lice released by the industry has been questioned by several NGOs and the 2018 committee. In September, Animal Equality UK exposed in a video investigation the removal of large quantities of dead salmon from a farm in Loch Linnhe, a few hours before an inspection by MPs from the rural affairs committee.
Expanding farms
The recent growth in Scottish salmon production capacity is driven by the increased demand for export. According to industry data, Scottish salmon generated £431 million ($544 million) between January and June 2024, and is the U.K.’s largest food export. In the same period, France remained the largest market, importing around 60% of Scottish salmon by value; imports to the U.S., China and Taiwan increased substantially.
“Scottish salmon is widely regarded as the best Atlantic farmed salmon that you can buy, and the more people become aware of that, the more demand for specifically Scottish salmon continues to increase,” Andrew Watson, communication manager at Salmon Scotland, told Mongabay.
In 2017, an industry working group published a growth strategy for farmed salmon in Scotland, aiming to double national production to 350,000 metric tons per year by 2030.
In September, Salmon Scotland issued a press release urging Scotland’s first minister, the head of the government, to speed up approvals for salmon farms, as “the current consents and licensing process is lengthy and involves several regulatory bodies, leading to significant delays.”
“If we want to export more salmon, then we need to be able to grow more salmon, and the only way we can grow more salmon is that we have more sites,” Watson told Mongabay.
Divided communities
According to Watson, to date “a number of companies” have applied for new licenses or expansion of production sites in Scotland, particularly in the Orkney Islands and the west coast. In September alone, the Scottish Coastal Communities Network documented two expansion requests and two requests for new sites made to public authorities by different companies in different locations.
Several of these expansion projects have met opposition from local communities. “Salmon farming has a long tradition in Skye,” Shona Cameron, member of the research platform Climavore, which advocates against farmed salmon, and a resident of the Isle of Skye, told Mongabay. According to Cameron, there are about 20 farms in Skye and several applications for new licenses or to extend the number of pens at existing farms.
“In the 1980s local people had small holdings, maybe one pen, and then gradually over the years we have seen multinational companies come in and buy the licenses,” she said.
“There’s definitely a split, a growing division within the islanders,” Cameron said. “A growing number of people that are questioning it, as an industry, and its role, and the idea of it’s either the environment or a job.”
Visiting five lochs in western Scotland for this story, Mongabay met as many community groups concerned about the impact on the environment. “What a lot of people want is just a moratorium on growth until they have addressed some of their issues, which are really well documented,” Ailsa McLellan, a resident of Loch Broom and a marine scientist who previously worked for the salmon farming industry, told Mongabay. “They are increasing their chemical use year on year, and that includes organophosphates. Nobody seems to be looking at the accumulative nutrient impact of [waste from] all these fish farms” on the seabed habitat, she said.
Other community members expressed concern about the role that the sea lice from the cages is playing in the decline of wild salmon. “There’s not enough salmon anymore,” Richard Wilkie, a member of Long Live Loch Linnhe, a group opposing a new farm in Loch Linnhe, told Mongabay. “The last salmon [fishing] station in Scotland was here on the bay, a small hut on the end there.”
In 2023, the IUCN classified the Atlantic salmon as endangered in Great Britain, after a 45% decline in populations since 2006. According to the IUCN, Atlantic salmon are decreasing globally due to multiple threats, including climate change, pollution, interbreeding with farmed salmon, and sea lice from salmon farms.
In Loch Linnhe, where there are already several salmon farms, a Scottish Environment Protection Agency report published in January identified a Mowi farm as among those making “the largest contribution to the exposure of wild salmon to infectious-stage sea lice.”
In the same loch, the Loch Long Salmon company has proposed to establish a new farm to produce 8,000 metric tons of fish per year in a floating semiclosed containment system.
“This will be filled with cages,” Karen Exard, another member of Long Live Loch Linnhe, told Mongabay, pointing to a bay behind her. Exard’s group is concerned about sea lice and organic waste from the new farm. “We have the tides coming in, so everything will be coming up here, towards the bay,” she said.
Exard said her group is taking care not to be too vocal about their opposition to the project so as not to divide the small local community. “But it’s not only about us, this is about the west coast of Scotland, and the possibility of having solutions to the current problems with salmon farms,” she said.
Banner image: Salmon farm in Loch Ainort in the Isle of Skye. Image by esc.ape(d) via Flickr (CC BY-NC-ND 2.0).
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