Fish farming, or aquaculture, is the industrial practice of raising fish in controlled environments for mass consumption. At a glance, marine fish farms may appear to offer a sustainable alternative to overfishing. But beneath the surface, they often create concentrated zones of pollution, disease, and ecological disruption.
Floating in the sea with no barrier between industrial waste and the surrounding marine environment. These create the most severe environmental problems.
Designed to limit some exchange with the ocean while still maintaining connection to marine waters for operational purposes.
Operating on land or in sealed tanks, providing complete separation from natural marine environments.
Open-net pen fish farms first appeared along British Columbia's coast in the 1970s, then rapidly expanded throughout the 1980s. Today, over 100 open-net pen salmon farms dot the province's coastline, clustered around the Discovery Islands, Broughton Archipelago, Tofino, Barkley Sound, Ocean Falls, Campbell River, Sayward, Port McNeill, and the Sunshine Coast.
More than 95% of the biomass produced by these farms consists of Atlantic salmon, a non-native species that has no natural place in Pacific waters. These foreign fish originate from Norwegian breeding stock, raised in freshwater hatcheries before being shipped to B.C.'s coastal farms as juvenile smolts, where they're confined in open nets directly in the ocean.
In such overcrowded populations, disease spreads rapidly, and fish frequently exhibit visible deformities, open lesions, and severe parasite infestations that ravage their bodies over time. Many don’t survive. Instead, they sink to the bottom of the nets, where their bodies remain, decomposing in the same confined waters the living fish are forced to endure.
Tenacibaculum maritimum causes "mouth rot" in farmed salmon, creating severe tissue damage and making feeding difficult for affected fish.
Piscine orthoreovirus (PRV) causes heart inflammation and severely weakened swimming ability in salmon. PRV has been found in 65-75% of B.C.'s open-net pen farmed salmon. Studies also show that PRV can be transferred from farmed Atlantic salmon to wild Pacific salmon.
Parasitic sea lice latch onto fish skin and feed on their flesh, leaving gaping open sores around the fins, head, and back. Sea lice become particularly lethal when they attach to juvenile salmon.

Photo by Tavish Campbell (juvenile chum salmon)
A Canadian study found that juvenile pink and chum salmon near fish farms in B.C. carried far more sea lice than those from areas with little or no farm exposure. The evidence is clear: proximity to farms is the biggest driver of infection. Even a small number of lice can kill a young salmon.
A massive sea lice infestation was reported in May 2018 in Clayoquot Sound where fish farm operator Cermaq reported that over half of its 14 farms were infested with sea lice levels that posed a serious threat to wild salmon. Sea lice levels averaged 34 lice per fish, over 10 times the legal limit of three motile lice per adult fish.

Photo by Tavish Campbell Discovery Islands (juvenile sockeye salmon)
When sea lice populations explode, fish farm operators release toxic chemicals directly into open-net pens—treatments that spread far beyond the farm boundaries into the surrounding ocean. These chemicals include hydrogen peroxide, azamethiphos, and deltamethrin. The collateral damage is severe: crustaceans, mollusks, and other essential marine species are killed alongside the intended parasites.
Up to one in five salmon die before harvest at some B.C. farms.
Mortality events recorded from 2011-2022.
These deaths represent millions of fish annually that never reach market, rotting masses of wasted life that make the environmental costs even more nauseating when weighed against actual food production.
As chemical treatments fail to control parasites, farms deploy hydrolicers, industrial machines that suction fish from pens and blast them with high-pressure water. Wild fish drawn into the pens by artificial lights and feed are sucked into these machines and killed during treatment.
Native species such as herring, and various wild salmon species are lured by artificial lighting and excess feed, only to become trapped within the pens where they inevitably die. Federal data reveals that in 2022 alone, over 817,000 herring, were killed, representing a devastating escalation from previous years.
Between 1990-2022, farms systematically killed 6,116 harbour seals, 1,426 California sea lions, and 379 Steller sea lions, shot or drowned to protect industry profits. Even humpback whales have been trapped, injured, and killed by salmon farm operations, demonstrating the industry's devastating impact on marine mammals of all sizes.

Photos: Clayoquot Action

These mass deaths represent far more than a wildlife tragedy, they constitute a direct assault on coastal ecosystems, food security, and fisheries. Many of the species being killed, including herring and wild salmon, serve as foundational elements in the diets of larger predators, support commercial fishers, and drive the nutrient cycles that sustain healthy oceans and forests.

The 2017 collapse of a Cooke Aquaculture net pen at Cypress Island off Washington's coast exposed the industry's reckless negligence. Initially reporting 160,000 escaped fish, the company was later forced to admit 263,000 Atlantic salmon had been released into Pacific waters after an investigation by Washington's Department of Natural Resources.
The cause? Cooke had systematically failed to clean and maintain its nets, allowing marine growth and debris to accumulate until the structure collapsed under its own neglect.
These escapees become aggressive competitors in Pacific waters, with Atlantic salmon growing 15-20% faster than native species and showing higher territorial aggression. They directly compete with endangered Chinook, Coho, and Chum salmon for critical feeding areas.
Studies show escaped Atlantics disrupt spawning behaviors of wild salmon, with male escapees attempting to mate with wild females, potentially compromising genetic integrity of native populations .
When DFO assumed control of salmon farms from the Province in 2010, it conveniently redefined "escape events" to include only those with "evidence of an escape", effectively erasing incidents from official records.
Previously, farms reported 400,000-800,000 escapes annually across B.C. operations. After 2010, reports mysteriously dropped to fewer than 1,000 per year. The Department now accepts ongoing "trickle losses" as simply the cost of industrial aquaculture.
The Department now accepts ongoing "trickle losses" as simply the cost of industrial aquaculture.
DFO has a conflict of interest, promoting aquaculture while also protecting wild fish. This dual role compromises its scientific advice, especially when it challenges industry growth.
Canada’s Public Sector Integrity Commissioner has launched an investigation into allegations that Fisheries and Oceans Canada attempted to silence federal scientists researching the environmental risks of open-net pen salmon farms. The inquiry, launched on June 17, 2024, will examine claims that scientists were reprimanded, prevented from speaking to the media, and blocked from testifying before Parliament.
There is also the case of Dr. Kristi Miller-Saunders who was prevented from publishing and speaking publicly about her research linking PRV (Piscine orthoreovirus) to disease in Pacific salmon. Her 2012 report was only released in 2022 after intervention from the federal Information Commissioner.
DFO has repeatedly ignored the precautionary principle, delaying action unless definitive proof of harm is available, often suppressing or silencing evidence that shows otherwise.
The science is clear: open-net salmon farms pollute our oceans, spread parasites and disease, and put wild salmon on the brink. It's time to act.
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May 21st, 2025
Damning government records and Remotely Operated Vehicle footage have exposed a "massive area" of ocean floor completely smothered in feces and rotting feed beneath Cermaq Canada's experimental salmon farm in Millar Channel, B.C. The salmon were treated with the antibiotic florfenicol at least seven times, including as recently as February, raising urgent concerns about antibiotic resistance and drug contamination in the surrounding marine environment. The overwhelming stench of decay, persistent fish oil slicks, and visible waste discharge cast serious doubt on the industry's promises about "closed containment" systems.
Diseased by Design: Canada’s Farmed Fish Betrayal