Scientists have discovered evidence of a virus in a freshwater sport fish in B.C. linked to a disease with a mortality rate of up to 20 per cent in farmed salmon — but a fish pathologist says the link is not necessarily causal and the virus is likely harmless.
Simon Fraser University fish-population statistician Rick Routledge and Stan Proboszcz, a fisheries biologist at the Watershed Watch Salmon Society, found evidence of the piscine reovirus (PRV) in 13 out of 15 cutthroat trout caught in Cultus Lake near Chilliwack, which was confirmed by four different labs.
The virus was linked for the first time two years ago to heart and skeletal muscle inflammation (HSMI) disease, a disease that has become widespread in Norwegian salmon farms.
“We think that this should be a wakeup call for the hundreds of thousands of sport fishermen in British Columbia that their resource might be threatened and they might be getting some inferior fish,” Routledge said Thursday.
But Gary Marty, a fish pathologist with the B.C. Ministry of Agriculture who sampled 500 farmed fish after the PRV virus was first discovered in Europe in 2009, said the 2010 study did not find a causal link between PRV and HSMI, and he doesn’t think the virus is to blame for the outbreak of HSMI in Norway.
“We don’t have any evidence of HSMI in British Columbia, but maybe two per cent of the [10 per cent of farmed] fish that die have a heart disease that might be due to a virus,” he said of his 2010 findings.
He compared the PRV virus in fish to the ubiquitous herpes virus that causes chickenpox in humans, saying that while almost everyone has it, most people don’t feel its effects.
He said he wonders if Routledge has a vendetta against the fish farm industry that may have been formed before improved standards over the past decade drastically reduced disease and mortality rates on fish farms.
While he was open to the idea of collaborating with Routledge on future comprehensive studies of the health of B.C.’s wild fish populations, he said the funding for that is not yet in place.