Anti-Salmon Farming Activists Twist New Science to Revive Old, Debunked Claims

A new scientific study is being ripped of its context and weaponized by anti-salmon farming activists to revive their discredited campaigns against ocean aquaculture in British Columbia.

By Fabian Dawson
SeaWestNews

For more than two decades, anti-fish farming activists in British Columbia have taken scientific findings out of context, amplified isolated fragments, and presented them as settled proof that ocean salmon farms must be shut down.

It is a strategy that has repeatedly confused the public, sustained activist fundraising campaigns, and pushed some federal ministers toward policy decisions that later collapsed under scientific scrutiny.

Now it is happening again.

A newly published study examining the bacterial disease tenacibaculosis is being misrepresented by activists to claim that Atlantic salmon farms were infecting coho salmon and that removing the ocean farms explains recent improvements in salmon returns.

One activist, whose pattern of misrepresenting fisheries science is well documented, seized on the study to declare: “Coho can be infected by Atlantic salmon. Makes it clear why Coho rebounded after salmon farms and their diseases were removed.”

Joseph Nowlan, the PhD student who spearheaded the trial in Dr. Spencer Russell’s Fish Health Laboratory at Vancouver Island University, noted that such claims single out one specific finding of the trial while ignoring what happened to the majority of the fish tested. 

“They’re taking the one fish that got sick and ignoring the others that were perfectly fine,” said Nowlan.

“It’s important to understand that yes, it can happen,” The study, conducted under controlled laboratory conditions, examined whether Tenacibaculum maritimum — a bacterium that causes tenacibaculosis — could transfer to coho salmon through prolonged cohabitation with farmed Atlantic salmon.

Nowlan said. “But they’re focusing on the exception, not what happens to the majority of the population.”

“We were able to find the bacteria on the coho salmon, but the overwhelming majority of the fish were not sick,” he added. “Only a very small proportion became ill. So yes, they can get sick, but it is unlikely.”

Out of roughly 80 coho salmon exposed to the bacterium, only four showed any signs of disease and those fish were already in poor physical condition, he said.

“You can find this bacterium in the water column, in sediments, on algae, bivalves, even whales,” Nowlan noted. “It’s prevalent. It is everywhere,” reflecting the widespread natural presence of the pathogen in coastal waters.

“It’s really hard to make direct inferences from lab studies to the wild,” he said. “If coho salmon around net pens are fit, feeding well, and properly acclimatized to saltwater, they’re unlikely to get the disease.”

“The presence of the bacteria isn’t an absolute indicator of whether an animal is susceptible to disease,” Nowlan added in an interview with SeaWestNews.

An earlier study authored by Nowlan investigating whether tenacibaculosisinduced by T. maritimum transfers from farmed Atlantic salmon to Chinook salmon, published last year in Aquaculture Research, reached a similar conclusion; BC Chinook salmon may not readily develop clinical tenacibaculosis under tested conditions, and that the presence of T. maritimum alone is insufficient for disease.

Those findings are consistent with assessments by the Canadian Science Advisory Secretariat (CSAS), which has concluded that disease transmission from farmed Atlantic salmon to wild Pacific salmon is unlikely and that any population-level impacts would be minimal to negligible.

This ongoing manipulation of science is reinforced by an activist echo chamber that rarely tests its claims against the full body of evidence, even as peer-reviewed research continues to show that wild and farmed salmon can coexist on British Columbia’s coast.

Among the most persistent claims now circulating is the assertion that recent strong salmon returns in B.C. are the result of salmon farm closures.

The historical record tells a different story.

The largest Fraser River sockeye return in modern history occurred in 2010, when an estimated 28.2 million fish returned while salmon farms were operating at peak production of roughly 90,000 tons a year. The Discovery Islands farms now blamed for suppressing wild stocks were not removed until 2022, making it biologically implausible for their absence to explain recent returns.

Data from the Pacific Salmon Foundation, an organization opposed to open-net salmon farming, supports that conclusion. Its long-term records show that record highs and lows in salmon abundance occurred both before salmon farming existed and during periods of peak farm production. Those swings are driven by ocean conditions, climate cycles, and freshwater habitat factors, not simply the presence or absence of farms.

The Department of Fisheries and Oceans Canada (DFO) has also urged caution. DFO has told SeaWestNews it does not have evidence showing that wild salmon populations rebounded as a result of marine farm closures.

That view is shared by Dr. Gary Marty, a veteran fish pathologist who spent more than two decades with the Animal Health Centre at British Columbia’s Ministry of Agriculture.

“Wild salmon populations went up and down before salmon farming began, they went up and down in the presence of salmon farms, and I am confident they will continue to go up and down if salmon farms are removed,” Dr. Marty has said.

Dr. Marty’s conclusions are rooted in a comprehensive 20-year review published in Aquaculture, Fish, and Fisheries, which found that salmon farms in B.C. have minimal, if any, long-term impact on wild salmon populations.

Large-scale datasets tell the same story.

A study published in Scientific Data by Nature assembled B.C.’s most comprehensive sea-lice dataset to date, covering more than two decades, nearly 100 farm sites, and over 365,000 wild fish. The authors found that sea-lice levels fluctuate naturally across years and regions and warned explicitly against cherry-picking short-term or localized data.

These studies and others add to a growing and increasingly rigorous body of scientific evidence concluding that salmon farms in B.C. do not harm wild salmon populations, states the B.C. Salmon Farmers Association.

But despite this body of evidence, Ottawa is pressing ahead with a proposed 2029 ban on ocean-based salmon farms in British Columbia, a policy legacy of the Trudeau era that was shaped more by activist pressure than by science.

B.C.’s salmon farmers and their First Nation partners are urging the Carney government to reverse the planned ban and replace it with a renewed, Indigenous-led approach to aquaculture. Under that framework, the sector estimates it could generate $2.5 billion in annual economic output and 9,000 jobs by 2030, rising to $4.2 billion and more than 16,000 jobs by 2040.

The uncertainty surrounding disease transmission between Atlantic and Pacific salmon is the central scientific question of Nowlan’s PhD research, which aims to provide data-driven clarity on fish health risks in the coastal environment.

Yet once again, a carefully qualified scientific finding has been torn from context and weaponized to advance an activist agenda masquerading as settled science.

(Main illustration courtesy of Mowi)