For the first time, a viral disease known to be fatal in Norwegian fish farms has been detected by a team of Canadian federal scientists in a salmon fish farm in British Columbia.
The disease, which is called Heart and Skeletal Muscle Inflammation (HSMI), has been connected to the deaths of at least 20 percent of the stock at several fish farms in Norway in the 1990s.
Because the disease has not been found in the western province before, scientists say they don't have sufficient evidence to know whether HSMI causes mortality or production issues in British Columbia.
Finding Cuts And Lesions
Led by Kristi Miller of the Fisheries and Oceans department, the team of scientists used cutting-edge technology to examine 2,400 live and dying salmon from four fish farms in Vancouver Island from 2013 to 2014.
They confirmed that lesions were detected on a salmon at one farm located in Johnstone Strait. The cuts indicated that the salmon indeed possessed HSMI.
Miller said in other parts of the world, the virus can be observed in freshwater fish. Now, they believe it strikes Atlantic salmon in B.C. as well.
However, while the virus can be observed in fish hatcheries, the prevalence can be much higher in the marine environment as evidenced by what transpired in Norwegian waters. Scientists fear that HSMI will spread to wild salmon once Atlantic salmon gets to the open ocean.
Link To Another Virus?
Miller and her colleagues tried to find a connection between HSMI and a virus called Piscine Reo-virus (PRV).
The latter was first identified in farmed salmon in Norway and has been linked to HSMI. However, experts have yet to determine whether PRV causes heart and skeletal inflammation among Atlantic salmon.
Although there is no definitive cause-and-effect relationship between the two, evidence suggests otherwise.
Rick Routledge, a professor at Simon Fraser University, said despite the low mortality rate of farmed fish, HSMI could really hurt the salmon.
"A fish that has heart disease and muscle damage ... it's not going to make it up to spawn," said Routledge.
Additionally, researchers did not find any evidence of HSMI among wild salmon in B.C. Miller said they know nothing about HSMI among wild fish.
"That's another thing that will require more work," said Miller.
Miller and her team's study is still in its initial stages and will continue.
Photo: U.S. Fish and Wildlife Service Northeast Region | Flickr
