Aerial view of a fish farm off the coast of northern Vancouver Island. File photo

Farmed Atlantic salmon in B.C. unaffected by virus, researchers find

Effects of piscine orthoreovirus, or PRV, under increased scrutiny following Federal Court decision

Newly published research says that piscine orthoreovirus (PRV) doesn’t cause severe heart inflammations in farmed Atlantic salmon in B.C., and their respiratory fitness is unaffected by the virus.

The two DFO-funded studies published online by peer-reviewed journals on Wednesday represent the latest developments in the controversy surrounding PRV.

The research suggests that PRV is less of a threat for Atlantic salmon in B.C. than in Norway, where it causes a deadly condition known as heart and skeletal muscle inflammation (HSMI).

“The PRV here, at least in our B.C. salmon, seems to have a lower capacity to cause disease than it does in Norway,” says Mark Polinski, co-author of the two studies and research scientist with Fisheries and Oceans Canada (DFO).

The virus infects Atlantic salmon throughout B.C. and is also found among wild Pacific salmon.

PRV-infected Atlantic salmon with severe heart inflammations turned up during audits on B.C. fish farms in recent years, and researchers wanted to know whether the virus was causing that HSMI-like condition.

One of the studies, this one by scientists from DFO and the B.C. Ministry of Agriculture, was published in the journal Scientific Reports.

READ MORE: Federal fisheries minister calls for precautionary approach to fish farming

Researchers injected Atlantic salmon with the virus, and compared those fish with a virus-free control group. They found the virus didn’t cause severe heart inflammations, although cases of minor inflammations increased, Polinski said.

The other study – written by scientists from DFO and the University of British Columbia and published online by the journal Frontiers in Physiology – found that PRV didn’t affect the cardiovascular and respiratory fitness of farmed Atlantic salmon.

READ MORE: Dissenter says effects of fish farm virus ‘extremely uncertain’

For the experiment, PRV-infected farmed B.C. Atlantic salmon were placed in a testing chamber with an oxygen sensor that measured the efficiency of their respiratory systems compared to virus-free fish.

“We get a new measure every ten minutes, and we do that for five days,” Polinski said.

Various indicators were measured, including recovery from exertion. The experiments showed no significant differences between infected and non-infected fish, Polinski explained.

While these tests involved Atlantic salmon, he added that tests on wild sockeye showed similar results, although those findings haven’t yet been published.

READ MORE: Ottawa won’t appeal Federal Court ruling on farmed salmon virus

Previous research indicates a connection between PRV and anemia in chinook salmon in B.C. The new studies don’t have any bearing on that research, Polinski said.

Asked why the two peer-reviewed articles were released on the same day, he said the Frontiers in Physiology article relied on research in the Scientific Reports article, so the former was held until the latter’s publication. Both studies were funded through grants from DFO.

This follows a series of events that have renewed scrutiny on the virus and its effects.

On Feb. 4, a Federal Court judge struck down a DFO policy allowing fish farm companies to transfer young Atlantic salmon into open-net pens without first screening them for PRV, saying the threshold for harm to wild stock was too high and the precautionary principle wasn’t met.

The court also ruled that Ottawa breached its duty to consult ‘Namgis First Nation about PRV policy.

READ MORE: Alexandra Morton, ‘Namgis First Nation win Federal Court ruling

The decision came in response to lawsuits brought forward by ‘Namgis First Nation and marine biologist Alexandra Morton, a prominent critic of the fish farm industry.

DFO said on Tuesday that it won’t appeal the decision. DFO’s court-ordered review of PRV policy is ongoing.

On the heels of the Feb. 4 ruling, DFO announced that participants in an expert peer-review process had reached a consensus that PRV poses minimal risk to Fraser River sockeye salmon.

That led to controversy when someone involved in that process – John Werring of the David Suzuki Foundation – said that no consensus exists, and that too much uncertainty remains about the pathogen and how it spreads.

PRV is just one bugbear for B.C.’s controversial aquaculture industry.

Opponents of open-net fish farming have long argued that salmon farms discharge harmful materials and contaminate the environment, spread sea lice and diseases among wild fish, and allow Atlantic salmon to escape, posing a variety of risks to wild stocks sacred to First Nations.

Industry critics have called for the removed of fish farms from B.C. waters. Alaska has banned open-net fish farms, while Washington State has begun phasing out its Atlantic salmon facilities, leaving B.C. as the hold-out in the Pacific Northwest.

Industry officials and other proponents say that concerns about fish farms are overblown and that open-net aquaculture provides a relatively green source of food, lowers pressure on wild stocks and provides economic benefits to B.C.

According to a study commissioned by the BC Salmon Farmers Association – which represents the fish farm industry – more than 2,900 people were employed directly in salmon farming by 2016.

Another 3,600 workers were either employed indirectly – that is, by industry suppliers – or due to spending by workers in the industry, according to the study.

@davidgordonkoch
david.koch@campbellrivermirror.com

Like us on Facebook and follow us on Twitter

Get local stories you won't find anywhere else right to your inbox.
Sign up here

Just Posted

Metchosin, Colwood hit with morning power outage

Monday morning outage impacts more than 2,600 BC Hydro customers

‘Someone knows something’: a look into Vancouver Island missing persons with interactive map

There are more than three dozen people listed as missing throughout Vancouver Island

Sooke Meals on Wheels seeks volunteers to replace critical roles

Annual general meeting, volunteer appreciation dinner is July 26

Colwood library reopens for public use July 18

Limited services offered Monday through Saturday

Faulty janitorial equipment likely caused Saanich school fire

Saturday morning fire damaged roof of Strawberry Vale Elementary

‘It’s really frustrating’: B.C. Indigenous groups share impact of border closures

The closures have resulted in disputes between Indigenous groups and local businesses

Beverly Hills 90210 star’s family selling Vancouver Island Beach Resort

You can own Jason Priestley’s Terrace Beach Resort in Ucluelet for less than $5 million

Islanders want BC Ferries to follow order that lets residents board before tourists

For ferry-dependent communities, ferries are often the sole practical lifeline to work, school or medical appointments.

Washington’s NFL team drops ‘Redskins’ name after 87 years

The franchise was given the name back in 1933, when it was still in Boston

Genetic detectives begin work to trace spread of COVID-19 in Canada

The kinds of genetic technology being used for this project did not exist when SARS hit Canada in 2003

Sports fishers protest Fraser River Chinook closures

Public Fishery Alliance wants hatchery fish open for harvest

B.C. Ferries increasing passenger capacity after COVID-19 restrictions

Transport Canada 50-per-cent limit being phased out, no current plans to provide masks

Shellfish industry get funds to clean up at Island sites and beyond

Businesses can apply to cover half of costs to clean up so-called ‘ghost gear’

Most Read