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PRV Virus poses minimal risk to Fraser River sockeye salmon

Press Release

“Unfortunately, some Canadian government non-medical researchers alike with US and Canadian activists are attempting to make this largely innocuous virus the scourge of the seven seas.”
By Fabian Dawson
SeaWestNews

WireService.ca Media Release (02/08/2019) – A Fisheries and Oceans Canada (DFO) science panel has concluded that the Piscine Orthoreovirus (PRV) poses minimal risk to Fraser River sockeye salmon, contrary to the claims being made by anti-fish farm opponents.

The virus also does not kill sockeye salmon or Atlantic salmon, the Canadian Science Advisory Secretariat (CSAS), which reviewed the latest Canadian and international data, concluded.

Gilles Olivier, CSAS’ National Peer Review co-chair told a media technical briefing today that farmed Atlantic smolts going into the ocean do not seem to have the PRV virus.

“They are going to sea without PRV and they are picking up PRV once they are at sea‚Ķthat’s what we seem to understand,” in response to a question from SeaWestNews during the briefing.

The study comes in the wake of a Federal Court ruling this week that struck down a Department of Fisheries and Oceans (DFO) policy on the transfer of baby salmon to the ocean environment.

At the core of the issue was the piscine orthoreovirus (PRV), which has been in the Pacific Northwest for many decades.

Despite the volume of peer reviewed scientific evidence that finds PRV does not cause disease in fish in the Pacific, anti-fish farm activist Alexandra Morton along with the ‘Namgis First Nation sued DFO claiming that salmon smolts being introduced to open pen facilities needed to be screened for the virus.

They claim that PRV is linked to disease in salmon.

The court rapped DFO for not consulting with the Namgis when it developed its PRV-salmon transfer policy.

It has given DFO four months to review the science and develop a new policy but it did not give any guidance on what that policy should be or if the new policy should include screening for PRV.

While today’s CSAS report backs the existing policy that there is no need to test for PRV when baby salmon are being transferred to the ocean environment, the scientists declined to comment directly on the court decision.

Jocelyn Lubczuk, a DFO spokesperson said: “The Department of Fisheries and Oceans will study the results of the Federal court decision, and will have more to say on the path forward in the weeks ahead.”

Dr. Jim Powell of the BC Centre for Aquatic Health Sciences (BCCAHS) – an independent lab – said the science to date suggests PRV in B.C. is benign and predates fish farms in B.C.

He said the significant body of science on the topic has found that it is likely a strain of PRV that naturally exists off the Pacific Coast and that it is a different strain than the one found in Norway, one that it isn’t harmful to either wild or farmed fish

Dr. Hugh Mitchell, a director of Northwest Aquaculture Alliance (NWAA) said there is no evidence anywhere that any variant of PRV has been involved in any massive die offs of farmed or wild salmon anywhere in the world.

“It is not regulated anywhere: nationally, regionally, or by individual States and is not listed by the OIE (World Organisation for Animal Health)- nor should it be,” said Dr. Mitchell, an aquaculture veterinarian with more than 25 years of experience.

“Unfortunately, some Canadian government non-medical researchers aligned with US and Canadian activists are attempting to make this mostly innocuous virus the scourge of the seven seas.

“They have generated scientific publications that have grossly exaggerated conclusions and that are not supported by their research.

“They have ignored and dismissed any research or researchers that are contrary to their beliefs, attacking those as biased or involved in a conflict of interest,” he said.

Today’s CSAS report only looked at the risk to Fraser River sockeye salmon due to Piscine Orthoreovirus (PRV) transfer from Atlantic salmon farms located in the Discovery Islands area, said Dr. Jay Parsons, Director of DFO’s Science of Aquaculture, Biotechnology and Aquatic Animal Health.

He said DFO is looking at conducting risk assessment studies of PRV in other species of Pacific Salmon.

Question and Answer: Piscine Reovirus (PRV)

What is PRV?

Piscine reovirus is a virus that can infect Atlantic and Pacific salmonids. Reoviruses get their name because many are respiratory and enteric orphans. They are called “orphans” because many are viruses without an associated disease.

Is PRV found in British Columbia?

Yes. Research published in 2014 suggests PRV has long been present in wild salmon in Pacific Northwest waters.

What impact does PRV have on salmon?

PRV has been detected in healthy fish in healthy populations, showing that its presence does not mean disease occurs.

But isn’t a virus a disease?

No. Not all germ’s in our environment cause disease. There are millions of viruses in every drop of seawater. Viruses are carried by all living things and most never cause disease. Other reoviruses have been found for decades in wild fish and never associated with disease. In British Columbia, there is no link between the presence of PRV and any disease.

Do salmon farmers test for PRV?

Yes. BC salmon farmers provided samples for the 2014 scientific study that documents PRV in BC and Alaska salmon without associated disease. BC salmon farmers are providing samples for other scientific studies that are underway. This is being done even though Fisheries and Oceans Canada (DFO), and the Canadian Food Inspection Agency (CFIA), do not have PRV on the list of reportable diseases/pathogens.

What about the suggested link between PRV and heart and skeletal muscle inflammation (HSMI)?

That link refers only to Norwegian strains of PRV in farmed Atlantic salmon. HSMI is common in Norway, but HSMI has never been identified in any wild fish in the Pacific Northwest. Viruses with the same name often occur as different types in different parts of the world. Some types might cause disease whereas others do not. PRV is a good example.

Is there any human health risk associated with PRV?

No. Viruses found in salmon (including PRV) are not a risk to human health.

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