
Scientists at the University of Gothenburg in Sweden recently concluded that some farmed salmon die from depression. (This may not be too surprising, given the conditions in which they are kept.) In other recent research, a team of US and Canadian scientists has charted an ominous trend: mass die-offs of farmed salmon are increasing in both frequency and scale. Some observers question whether the industry, after decades of growth, may be past its peak and about to decline.
Meanwhile, DFO suggests that salmon farming licenses should be renewed this summer for six years rather than the current standard term of two years — only five years after Prime Minister Justin Trudeau made a campaign promise to shut down net-pen salmon farming in BC altogether by 2025.

Stressed-out Fish
The Swedish team made the most extensive study to date of what the industry calls “drop out” fish — salmon which fail to thrive and then die early. Their research found high levels of cortisol and other serotonergic symptoms in the dead fish, markers typical of high anxiety and stress.
Humans facing poverty and other socioeconomic hardships are more likely to be diagnosed with depression and mental illness. It appears unnatural and stressful environments can have a similar influence on farm-raised fish.
Farm-raised salmon and other fish live in crowded tanks where they must tolerate the presence of aggressive fish and battle for food. They must also endure sporadic changes in lighting, water depth, currents and more.
“Farmed fish live in a very stressful environment, since the conditions in aquaculture farms are extremely different from what they have evolved to cope with in the wild,” Vindas said.
—- Farm-raised salmon suffer from depression, UPI — May 2016
CAFO conditions are stressful for any organism; salmon, though they are fish rather than poultry, pigs, or cattle, apparently suffer comparable levels of misery and disease from their unnatural confinement.
What is CAFO? The acronym stands for “Concentrated Animal Feeding Operation,” or what is commonly called a “feedlot” in the beef industry. It’s any animal husbandry operation at factory scale, in which animals are kept in densely concentrated confinement and fed a tailored diet with a view to (a) maximising meat production per facility square foot and (b) minimising time to market. What the industry calls “salmon farms” far more resemble “salmon feedlots.” While “farm” suggests bucolic imagery of happy cattle in green fields, a feedlot is quite another matter — or in our case, quite another kettle of unhappy fish.
Mass Mortality Events in CAFO Salmon: a new study
The CAFO approach to agriculture (or salmon aquaculture) involes significant risk. There’s more at stake here than a few very depressed fish who fail to thrive and die young. A March 2024 paper by Gerald Singh, Zaman Sajid and Charles Mather documents a disturbing global trend:
Using a global dataset of publicly available and government-collated data on salmon mortality events including nations responsible for the majority of salmon aquaculture, we document trends in mortality events, showing that in some of the major salmon producing nations of the world (in particular Norway, Canada, and the UK), mass mortality events have increased in frequency from 2012 to 2022. We also show that the scope of mass mortality events has increased over time—that is, the upper bound of how many fish were killed in a specific mortality event has increased over time.
—- Quantitative analysis of mass mortality events in salmon aquaculture, Nature — March 2024
The six largest salmon producing nations have lost 865 million Atlantic salmon to mass die-offs in just the last decade. Why are more and more CAFO salmon dying in mass mortality events, more and more frequently? The authors ascribe the escalating die-off trend partly to increasingly unstable weather conditions in a changing climate; but they emphasize that an equally important cause is the industry’s attempts to use technology to maximise production.

The unnaturally close confinement and crowded conditions in a CAFO not only cause stress and depression in the incarcerated fish; as with all CAFO situations, the stressed and crowded animals are a perfect laboratory for infectious diseases and parasites. To keep them (more or less) healthy in such inherently unhealthy conditions, the industry relies on chemicals and pharmaceuticals — and runs into the inevitable diminishing returns and unforeseen consequences:
[…] salmon mortality within aquaculture production facilities can often be the result of production practices such as mechanical and thermal delousing that coincide with other environmental and physiological conditions compromising fish health. Similarly, overuse of antibiotics and antiparasitics can cause bacteria and parasites to develop resistance to them, and these treatments can become ineffective, which leads to an increased risk of MMEs.
Manufactured Risk
Warming waters stress the fish even further and provide a friendlier environment for various parasites and diseases. But the vulnerability of the fish to these pathogens is artificially enhanced by the CAFO system in which they are kept. The technical term for this kind of blowback is “manufactured risk.”
Manufactured risk occurs when human decisions and infrastructure create or enhance contexts for consequential events. Manufactured risks are frequently the outcome of industrialization and modernization, in which technology and procedures are developed to boost efficiency and output — but can also represent dangers if not managed appropriately, or increase vulnerability to disasters by exposing a system to greater environmental variation that serve as hazards. [ibid.]
The authors stress that mass mortality events or MMEs not only involve financial loss and the death of millions of living creatures; they have knock-on effects for the workers and the local economies of towns and villages that have “bet the farm” on fish farming.

Aquaculture operations manufacture systems where high densities of salmon allow for large populations to face mortality-inducing conditions simultaneously. The consequences of these MMEs are not limited to the stock of salmon but can have significant impacts to the surrounding environment (through nutrient release and the creation of anoxic “dead zones”) and the people working in the aquaculture production facilities, and the consequences tend to worsen with increased magnitude of MMEs. For example, MMEs can be met with regulation that strips a company’s permit to raise fish, which can devastate local economies. The process of collecting and disposing of large volumes of dead fish may also have potential occupational health and safety consequences for workers involved in these labour-intensive and potentially risky tasks.[ibid.]
The salmon CAFO industry, like other CAFO sectors, is trying to apply industrial/factory methods to the husbandry of living creatures. The industry keeps a far-ranging marine species — Atlantic salmon — in close captivity, in unnatural conditions that could be described as “cruel.” It attempts to overcome the resulting illness and stress of the fish by applying technological bandaids. The authors of this first wide-ranging historical survey of mass mortality events in CAFO salmon suggest that this approach has only escalated the industry’s manufactured risk over several decades.
[…] the growing scope of loss may be a consequence of the technologies and practices intended to increase productivity at production sites, such as technology to optimize production conditions and a greater tendency to move production sites offshore.
The increase in distribution, frequency, and scope of the magnitude of MMEs adds to the growing concerns about global aquaculture’s ability to feed the future. […] There is also concern that future growth in aquaculture is optimistic, with recent research suggesting that global aquaculture has peaked and may be on the verge of decline. [ibid.]
Particularly when such large amounts of money are at stake there will be attempts by the industry to brush off mass die offs as random natural disasters. But our authors disagree:
[…] In the case of aquaculture, while MMEs in salmon aquaculture are often blamed on climate change or other environmental variables, close analysis of the events always reveals some form of human cause coupled with an environmental stress. Attributing cause to environmental variables ignores the important human dimension to disaster and can deflect responsibility and accountability [ibid.]
An industry on shaky ground?
The salmon CAFO industry runs at extremely high risk, particularly in open-water net-pen operations exposed to extreme weather and impacting the surrounding natural environment. We are all familiar with the negative impacts of net-pen Atlantic salmon CAFO on BC’s wild salmon stocks, and this effect is consistent world-wide:

The impact of salmon farming on wild salmon and trout is a hotly debated issue in all countries where salmon farms and wild salmon coexist. Studies have clearly shown that escaped farm salmon breed with wild populations to the detriment of the wild stocks, and that diseases and parasites are passed from farm to wild salmon. An understanding of the importance of these impacts at the population level, however, has been lacking. In this study, we used existing data on salmon populations to compare survival of salmon and trout that swim past salmon farms early in their life cycle with the survival of nearby populations that are not exposed to salmon farms. We have detected a significant decline in survival of populations that are exposed to salmon farms, correlated with the increase in farmed salmon production in five regions. Combining the regional estimates statistically, we find a reduction in survival or abundance of wild populations of more than 50% per generation on average, associated with salmon farming. Many of the salmon populations we investigated are at dramatically reduced abundance, and reducing threats to them is necessary for their survival. Reducing impacts of salmon farming on wild salmon should be a high priority.
—- A Global Assessment of Salmon Aquaculture Impacts on Wild Salmonids, PLOS Biology — February 2008
But in discussing the risks the industry inflicts on wild stocks, we should not lose sight of the risks it inflicts on itself and its own captive salmon. The very methods the industry uses to maximise profits are those which escalate the risk to their CAFO fish — and by extension, to communities where salmon CAFOs have been adopted as an economic mainstay. The depressed, diseased, overstressed fish are vulnerable to mass die-off events of a magnitude sufficient to have severe impacts not only on the surrounding natural environment, but on workers and entire communities.
In Chile in 2016 an MME at a production site in the Chiloe region caused by red tide resulted in the death of over 6 million fish, representing more than 12 per cent of annual production. The economic and social costs to the Chiloe region were significant: 4,500 people directly employed by the industry lost their jobs and the livelihoods of 6,000 inshore fisherman were affected, and even the tourism sector was affected because of the environmental impact associated with disposing of dead fish.
—- Quantitative analysis of mass mortality events in salmon aquaculture, Nature — March 2024
BC net-pen salmon CAFO to be phased out… or not…
Scientifically substantiated testimony of the harm done to wild salmon by CAFO Atlantic salmon production has been accumulating for decades. In BC the vast majority of the Atlantic salmon fish farming industry is Norwegian owned. But Canada still has regulatory power within its sovereign territory.
In response to the accumulating evidence of environmental damage. Prime minister Justin Trudeau in 2019 promised he would give the farm salmon industry in BC only until 2025 to transition away from net pen CAFO, presumably to take their operations on shore. However, some observers fear that the federal government may be weakening in its resolve to protect BC’s wild salmon; the government is now saying that, rather than forcing salmon CAFO out of BC coastal waters by that date, it will instead have a “transition plan” ready by 2025.

On June 30th of this summer, all of the 85 finfish farming licences on the BC coast will expire; renewals are requested for 66 of them. What will the Trudeau government do?
Proposals from DFO are not encouraging for wild salmon advocates. Among some regulatory updates, we find language suggesting that license terms should be extended to six years rather than (at present) two years. Licenses for business-as-usual net-pen salmon CAFO, if renewed for six years this summer, would still be valid until the summer of 2030 — five years later than the deadline by which Trudeau initially promised to phase out these operations for good.
In 2022, witnesses at a government hearing expressed concern that the BC salmon farming industry — which claims it is worth $1.1B US per year — was exercising undue influence at DFO. MP Elizabeth May strongly criticised DFO, reviving long-standing suggestions that it should not hold simultaneously a mandate to promote salmon farming and a mandate to protect wild stocks.
What we see relating to science and DFO and the aquaculture industry is not incompetence, not scientific illiteracy, but deliberately dishonest efforts to block science, keep a minister in the dark and advantage the industry.
—- Elizabeth May, quoted in the Tyee “DFO Suppresses Science and Pushes Salmon Farms.” May 13th 2022

[Illustrations by Midjourney, prompts by author. Note: voices heard reading quoted text in the radio version are AI generated, and are not the voices of the text authors –or of the real Elizabeth May! They are used only to make it clear where the quoted material begins and ends.]