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Thousands of wild fish trapped inside a farm cage containing starving farmed salmon have been captured in footage released by animal advocacy organisation Animal Equality UK.
Supermarket giant Tesco has suspended its sourcing from Aird farm, operated by Bakkafrost, after the video showed a cage holding farmed Atlantic salmon afflicted by sea lice and disease despite it being reported as being fallow, and therefore empty.
Read: The catch
A spokesperson from Salmon Scotland told The Ecologist last night: “Extreme anti-salmon farming groups like Animal Equality UK routinely misrepresent the sector with unevidenced allegations."
Flesh-eating
Experts warn that breaches of fallow licensing conditions pose a serious threat not only to farmed fish welfare but also to smaller wild fish populations that enter the farms for shelter or food, but then often grow too large to be able to subsequently exit the cages.
These wild fish will be susceptible to the same challenges faced by farmed fish, including exposure to flesh-eating sea lice that are rife within Scottish salmon farms. Publicly available data indicate that nearly one-quarter of active salmon farms are in breach of the industry’s own lice Code of Good Practice.
Animal Equality UK conducted an analysis and discovered hundreds of weekly breaches, many during the months when juvenile wild salmon and trout are migrating from rivers to sea - their most vulnerable life stage.
In 2025, during the sensitive period, there were 623 weekly reports where lice counts exceeded the 0.5 threshold. There were also 464 instances where no count was carried out.
All four of the major salmon farm companies operating in Scotland had sites where counts repeatedly went well above the threshold: This includes the Scottish Sea Farms run Dunstaffnage farm; the Cooke Aquaculture run Chalmers Hope farm; the Bakkafrost run Gob a Bharra farm and also the Mowi run Loch Leven farm.
In addition to parasites, pathogens, chemical residues, and other treatments can persist in cages. Fallow sites are expected to undergo complete removal of fish and nets to limit pathogen carryover. Campaigners, however, say the Aird site “continued functioning as a reservoir of disease and flesh-eating lice.”
Unsustainable
Abigail Penny, executive director of Animal Equality UK, said: “Just like farmed salmon, vast numbers of wild fish become trapped inside these underwater cages, exposing them to the same harsh and harmful practices.
"They too face exposure to parasitic sea lice, disease, predation, and toxic chemicals, yet the number of wild fish dying in these cages remains undisclosed. Because of reporting loopholes, the true scale of death on Scottish salmon farms is still unknown.
"The industry does not reveal how many farmed fish are culled, die in transport, or perish within the first six weeks of entering sea cages. The public has a right to know what is happening beneath the water.”
She added: “Wild fish already suffer in unimaginable numbers at the hands of the salmon farming industry - trawled from the sea to become feed for carnivorous salmon, or taken as ‘cleanerfish’ to eat the lice off of the farmed fish. There is so much hidden harm within salmon farming, it is fundamentally unsustainable.”
Studies show that wild fish routinely enter salmon farms around the world, sometimes by the tens or hundreds of thousands.
Dwindling
In Canada, ‘incidental catch’ - wild fish from within the fish farms that are caught during harvest, movement between or within facilities, or removed from the nets - are publicly reported by the salmon industry, although no data is provided for the wild fish trapped in cages throughout the entire farming cycle.
According to Canadian NGO Watershed Watch Salmon Society, wild fish entering salmon farms may be negatively impacted in a number of ways, including being eaten by farm salmon, infected with pathogens and/or parasites from farm fish and contaminated with pesticides, medications and other toxins through eating fish farm feed.
In late 2024, the Scottish Parliament’s Rural Affairs and Islands Committee conducted a nine-month inquiry into the Scottish salmon farming industry, following a similar inquiry in 2018, prompted due to environmental concerns posed by the industry.
The committee referenced concerns about the industry’s potential impact on dwindling wild salmon and trout populations, due to the possible spread of deadly pathogens or parasites. This latest footage suggests wild aquatic animal species may be affected by the industry in other ways that are currently under-researched.
Concerning
The Ecologist contacted Tesco, Scottish Sea Farms, Cooke Aquaculture, Bakkafrost and Mowi for comment. A spokesperson for Cooke Aquaculture said: "In regards to your enquiry, Salmon Scotland will be responding on behalf of the sector."
The spokesperson from Salmon Scotland stated: “Scottish salmon farmers operate to some of the highest health, welfare, and environmental standards in the world, with sea lice levels now among the lowest on record.
“A small number of wild fish may occasionally pass through farms in the open sea, but there is no evidence this affects the welfare of either farmed or wild fish, and using footage from a single site to make sweeping claims about an entire sector is misleading.
“Farms must meet strict fallow and environmental standards, and where issues arise they are investigated and addressed through a robust regulatory system.”
A Tesco spokesperson said: “As soon as we were made aware of this concerning footage, we immediately suspended the farm to carry out an investigation with our supplier. Any failure to meet our high welfare standards is unacceptable and we take swift action where necessary."
This Author
Brendan Montague is an editor of The Ecologist.
