Going viral: testing Clayoquot Sound salmon farms for PRV

Norwegian virus threatens wild salmon in UNESCO biosphere reserve

Dan Lewis

Photo © Clayoquot Action

Wild salmon are on the brink of extinction in the Clayoquot Sound UNESCO Biosphere Region surrounding Tofino. Returns of Chinook in 2019 were some of the lowest ever recorded. The Megin River in Strathcona Park saw a mere eight Chinook return to spawn; the Moyeha — the adjacent valley — saw only 20. With the abundance of pristine rainforest habitat in these watersheds, we can rule out impacts from logging — something else is going on.

There could be several factors at play, but with 20 salmon farms on the migration routes of wild salmon, that seemed like an obvious place to look for answers. That’s why Clayoquot Action launched Going Viral, a project to field-test Clayoquot Sound salmon farms for the highly contagious Norwegian piscine orthoreovirus (PRV).

The method we used was developed by biologist Alexandra Morton. Because BC fish farms use open-net pens, things flow in and out. Sea lice, bits of decomposing farmed fish, and viral particles flow out freely to pollute the marine environment.

Cermaq’s Binns Island farm, aerial photo Nov 2019 | © Clayoquot Action

This means we can take samples from fish farms and test them for pathogens. We approach the farm very closely, stand on the prow of the boat with aquarium nets on poles, and scoop up bits of flesh, fat, feces or fish scales. Sometimes this takes just minutes; other times we strained our eyes for an hour in order to fill a couple of vials.

The samples were placed in a virus preservative and shipped to the Atlantic Veterinary College for testing.

Here are the results as we go to press: of the farms stocked with fish during the study period, 90% of Cermaq’s eleven active farms tested positive for PRV; 100% of Creative Salmon’s four active farms also tested positive for PRV. The lab has done further testing on our samples to confirm that the virus Clayoquot Action is finding is the Atlantic PRV1a sequence variant. (Kibenge et al 2013)

© Clayoquot Action

It’s alarming to confirm that a virus from the Atlantic Ocean has been found coming from Atlantic salmon farms in a UNESCO Biosphere Reserve on the Pacific. It is of particular concern that Creative Salmon is rearing Pacific Chinook in their farms that tested positive for this virus. One has to ask where they got it from – could it have come from Cermaq’s farmed Atlantics, or is their hatchery infected?

Pacific salmon respond to this virus differently than Atlantic salmon.1,2 In Atlantic salmon, PRV causes Heart and Skeletal Muscle Inflammation (HSMI) which makes it hard for fish to feed themselves, evade predators or swim up rivers to spawn. Farm salmon – protected from predators – often recover. In Pacific Chinook, PRV fills their red blood cells until they explode, overwhelming the liver, causing organ failure, and causing the fish to become jaundiced. In sockeye, PRV causes lesions to form on the heart.

Creative’s salmon are processed at a plant in Tofino, made famous a couple of years ago when photographer Tavish Campbell dove and filmed the bloodwater spewing into the harbour. Although the visuals of the blood gushing out of that pipe were disturbing, what was truly alarming is that the blood was tainted with PRV.3 That means that wild fish swimming through Tofino Harbour are being exposed to PRV, and currents are carrying viral particles into the Sound. Because fish breathe through gills, it is dead easy for viral particles to get into the blood of wild fish.

It’s not easy to find PRV in wild salmon, because unlike salmon in captivity, they do not have the luxury of being fed and protected from predators. One study found fewer and fewer wild fish testing positive for PRV as you move away from the salmon farms and up the Fraser River.4 This suggests wild salmon exposed to salmon farms are becoming infected, and that infected salmon are having difficulty swimming up rivers.

The Liberal government promised during the 2019 election to remove open-net pen salmon farms from BC waters by 2025. This was reflected in the mandate letter to new Fisheries Minister Bernadette Jordan. Local MP Gord Johns (NDP Fisheries critic) is determined to push hard for early legislation in order to ensure an orderly transition for workers and communities.

Washington State passed similar legislation in 2018 due to the risk to wild salmon, leaving BC the only jurisdiction on the west coast of North America permitting open-net pen salmon farms. In the interim, Washington is not allowing PRV-infected fish to be put into salmon farms – in fact they’ve ordered that 1.8 million fish be destroyed, rather than put their wild salmon at risk (the industry has been unable to find any uninfected fish to stock their farms with).

In BC, three lawsuits (two by Ecojustice, and another by the ‘Namgis First Nation) have successfully challenged DFO’s policy of putting PRV-infected fish in farms. However, DFO managers continue with this dangerous practice, perhaps because the industry complained to the court that prohibiting the transfer of PRV-infected smolts from hatcheries into the farms would “severely” impact them.

There are two important reasons why we should not allow PRV-infected salmon into BC open-net pens: salmon farms amplify viruses and broadcast them to the surrounding environment, and salmon farms allow the virus to breed, mutate, and become more virulent – as happened in Norway.

With the extinction trajectory that wild salmon are on, it’s past time to demand that DFO immediately stop the transfer of PRV-infected fish into open-net pen salmon farms. Add your voice to the petition on salmonpeople.ca.

Read the full Going Viral report here.

Dan Lewis is executive director of Clayoquot Action in Tofino.

This article appears in our February-March 2020 issue.






  1. Di Cicco & Miller (2018)
  2. Garver et al (2016)
  3. Pers comm Alexandra Morton (work to be published)
  4. The effect of exposure to farmed salmon on piscine orthoreovirus infection and fitness in wild Pacific salmon in British Columbia, Canada, Morton et al (2017)

Related Posts

Watershed Sentinel Original Content

5 Issues/yr — $25 print; $15 digital