A feared viral disease proven deadly in Norwegian fish farms has been confirmed for the first time by federal scientists studying farmed salmon in B.C.

Heart and Skeletal Muscle Inflammation (HSMI) has been linked to the deaths of up to 20 per cent of stock at some Norwegian farms.

"The concern is that it is a disease that hasn't previously been detected in B.C. and at the present time we really don't have sufficient evidence to know if it causes mortality or is a production issue here," said Kristi Miller, part of a team of federal scientists studying farmed fish samples from sites along the B.C. coast.

Miller, head of the molecular genetics research program in the Department of Fisheries and Oceans (DFO), confirmed that pathologists found lesions on salmon at one farm in Johnstone Strait, along the northeast coast of Vancouver Island.

The lesions indicated that the fish had HSMI, a disease found in several countries including Norway in the late 1990s, where it was linked to low levels of mortality ranging from 0-20 per cent on various farms.

A fish that has heart disease and muscle damage ... it's not going to make it up to spawn - Rick Routledge, Simon Fraser University professor

"We know that this virus, in other parts of the world, can be observed in freshwater origin fish and we believe we know that here in B.C. in Atlantic salmon," Miller said Friday.

"But in Norway, while the virus can be observed in fish in hatcheries, the prevalence of the virus can become much, much higher in the marine environment," she added.

The fear is that the virus will spread to wild fish once it gets into the open ocean.

Miller's team used cutting-edge technology and collaborated with international scientists to study 2,400 live and dying salmon from four Vancouver island fish farms from 2013-2015..

Scientists are trying to define the relationship between HSMI and a virus known as Piscine Reo-virus (PRV).

This virus was first identified in farmed Atlantic salmon in Norway. It's linked to HSMI, but research is still underway to determine whether PVR is the cause of the heart and skeletal inflammation.

While experts say there is no definitive proof that one causes the other, the evidence suggests that relationship.

Simon Fraser University professor Rick Routledge said that despite the low mortality of farmed fish, HSMI could really hurt wild salmon.

"A fish that has heart disease and muscle damage ... it's not going to make it up to spawn," said Routledge.

Federal biologists have found no evidence of HSMI disease in wild salmon in B.C.

Research is still in early stages, and will continue.

With files from Stephanie Mercier