An Atlantic salmon is seen during a Department of Fisheries and Oceans fish health audit at the Okisollo fish farm near Campbell River, B.C., Wednesday, Oct. 31, 2018. THE CANADIAN PRESS /Jonathan Hayward

An Atlantic salmon is seen during a Department of Fisheries and Oceans fish health audit at the Okisollo fish farm near Campbell River, B.C., Wednesday, Oct. 31, 2018. THE CANADIAN PRESS /Jonathan Hayward

Farmed salmon virus source, amplifies disease transmission in wild salmon: B.C. study

Mordecai said evidence is mounting that B.C. aquaculture operations pass the virus to wild salmon

Evidence shows a debilitating virus found in British Columbia salmon was transferred from Atlantic fish farms, which then spread from Pacific aquaculture operations into wild fish, says a study published Wednesday.

The researchers used genome sequencing to trace the piscine orthoreovirus, or PRV, that they say was first introduced to B.C. waters from Norway about 30 years ago at the start of open-net pen aquaculture in the province.

The study, published in the peer-reviewed journal Science Advances, says the evidence now suggests the virus is continuously spread between farmed and wild Pacific salmon as they migrate past the farms.

PRV, which devastated salmon farms in Norway, is a disease linked to heart and skeletal muscle inflammation in farmed salmon, and kidney and liver damage in wild B.C. salmon.

The research was conducted by experts from the University of British Columbia and the Strategic Salmon Health Initiative, a partnership of Fisheries and Oceans Canada, Genome BC and the Pacific Salmon Foundation.

“One of the cool things about our study is we demonstrate that this genomic technology, which has been developed to survey viral pathogens in humans, can be translated and used to study a really important fishery resource,” said Dr. Gideon Mordecai, a viral ecologist at the university’s department of medicine.

In an interview, Mordecai said the researchers sequenced 86 complete PRV genomes and concluded the lineage of the virus in B.C. originates from the North Atlantic.

“This is consistent with the timing of Atlantic salmon egg imports from Europe for salmon farms in the northeast Pacific,” the study says.

Mordecai said evidence is mounting that B.C. aquaculture operations pass the virus to wild salmon, with increased infection rates found the closer wild salmon are to the fish farms.

“This virus has been introduced to the region,” Mordecai said. “It wasn’t naturally here. It’s been introduced by people, and it continues to be introduced by the high infections that are in the stocked net pens and that’s having an effect.”

The B.C. Salmon Farmers’ Association said Wednesday it will review the study but pointed to archived salmon tissue from 1977 indicating PRV was present in B.C. waters before the establishment of fish farms.

It said in a statement the PRV strain in B.C. is genetically different from the virus in Europe, while it disputed the UBC research that the disease arrived on the West Coast from Norway.

“We are not importing anything,’” the statement said. “The Atlantic salmon we farm in B.C. is 100 per cent B.C. grown. Our fish are raised in hatcheries on Vancouver Island, from brood stock born and raised on Vancouver Island.”

The federal Department of Fisheries and Oceans says in a statement it supports new research to help identify and understand potential risks associated with the various strains of PRV.

“The Mordecai … paper provides valuable information on the origin, evolution and potential transmission dynamics of PRV-1a,” says the statement. “The department will be considering these findings alongside additional studies on PRV in B.C.’s coastal waters.”

The department has conducted numerous studies on the effects of PRV on farmed Atlantic salmon and wild salmon, but found minimal risk to wild stocks.

Indigenous groups opposed to aquaculture in their traditional territories, especially near the Discovery Islands off northern Vancouver Island, say the proximity of fish farms to wild salmon migration routes increases their disease risk.

The federal government announced the phase out of almost 20 open-net fish farms last December in the Discovery Islands area over the next 18 months.

Mordecai, who earned his doctorate researching honey bee pathogens, said he was spurred to study salmon health after attending academic conferences where government scientists expressed confidence PRV did not pose major risk to wild salmon.

“I thought, ‘Well, I better ask that question,’” he said. “The government’s lines are the virus poses minimal threat to salmon. It’s low risk. It doesn’t cause disease and the virus is endemic to the region.”

But the genome sequencing results provides evidence that salmon farms serve as a source of the virus to B.C.’s wild salmon, Mordecai said.

The study calls for more monitoring and regulation of infectious diseases threatening wild salmon.

“Although infectious disease is just one of many threats to marine organisms, fully understanding the health status of at-risk wild populations will only be possible if management agencies continue to invest in active monitoring for emerging infectious diseases,” says the study.

“Our study highlights the need for robust regulation of aquaculture that may prevent future losses in wild populations, which we propose may be exacerbated by PRV-1 and other emerging infectious diseases.”

Dirk Meissner, The Canadian Press

Salmon

Just Posted

FILE – Perry Bellegarde, National Chief of the Assembly of First Nations, takes part in an event on Parliament Hill in Ottawa on Tuesday, July 7, 2020. THE CANADIAN PRESS/Sean Kilpatrick
Indigenous Peoples Day must be a ‘call to action’, says Assembly of First Nations chief

Discovery of children at Kamloops residential school site must lead to change, Perry Bellegarde says

The Binche Fishing Derby at Stuart Lake is fast approaching. (Binche Fishing Derby Facebook photo)
Binche shares excitement for upcoming fishing derby

“It’s more than just fishing,” says Dave Birdi

A person receives a COVID-19 vaccine at a vaccination clinic run by Vancouver Coastal Health, in Richmond, B.C., Saturday, April 10, 2021. (THE CANADIAN PRESS/Jonathan Hayward)
Local youth vaccination clinics underway

Pfizer vaccine will be used

The border crossing into the United States is seen during the COVID-19 pandemic in Lacolle, Que. on February 12, 2021. THE CANADIAN PRESS/Paul Chiasson
VIDEO: Border quarantine to soon lift for fully vaccinated Canadians

Eligible travellers must still take multiple COVID-19 tests

Chilliwack secondary school’s principal is apologizing after a quote equating graduation with the end of slavery in the U.S. was included in the 2020-2021 yearbook. (Screenshot from submitted SnapChat)
B.C. student’s yearbook quote equates grad to end of slavery; principal cites editing error

Black former student ‘disgusted’ as CSS principal apologizes for what is called an editing error

Skeena MLA Ellis Ross. (Photo by Peter Versteege)
BC Liberal leadership candidate condemns ‘senseless violence’ of Okanagan church fires

Skeena MLA Ellis Ross says reconciliation isn’t about revenge for past tragedies

A coroner’s inquest will be taking place at the Capitol Theatre in Port Alberni for the next week. (ELENA RARDON / ALBERNI VALLEY NEWS)
Teen B.C. mom who died following police custody recalled as ‘friend to many’

Police sent Jocelyn George to hospital after intoxication had gone ‘beyond the realm’ of normal detox

Cannabis bought in British Columbia (Ashley Wadhwani/Black Press Media)
Is it time to start thinking about greener ways to package cannabis?

Packaging suppliers are still figuring eco-friendly and affordable packaging options that fit the mandates of Cannabis Regulations

FILE - In this Nov. 29, 2020, file photo, Las Vegas Raiders defensive end Carl Nassib leaves the field after an NFL football game against the Atlanta Falcons in Atlanta. Nassib on Monday, June 21, 2021, became the first active NFL player to come out as gay. Nassib announced the news on Instagram, saying he was not doing it for the attention but because “I just think that representation and visibility are so important.” (AP Photo/John Bazemore, File)
Nassib becomes first active NFL player to come out as gay

More than a dozen NFL players have come out as gay after their careers were over

Penticton Indian Band Chief Greg Gabriel speaks to the Sacred Hearts Catholic Church burning down early Monday morning, June 21, 2021. (Monique Tamminga Western News)
Penticton band chief condemns suspicious burning of 2 Catholic churches

Both Catholic church fires are deemed suspicious, says RCMP

COVID-19 daily cases reported to B.C. public health, seven-day moving average to June 17, 2021. (B.C. Centre for Disease Control)
B.C.’s COVID-19 infections drop to 90 on Sunday, 45 Monday

Pandemic spread dwindles as 77% of adults receive vaccine

By protesting uninvited in First Nations’ territories, conservationists are acting in a neocolonial or paternalistic manner, says Huu-ay-aht Chief Robert Dennis. Photo by Heather Thomson
A closer look: do Vancouver Island First Nations support the war in the woods?

First Nations/environmentalist old growth alliance uneasy, if it exists at all

Most Read