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Atlantic salmon for sale in Canada, Jan. 9, 2004 .Fred Lum/ The Globe and Mail

Fish-farm critic and independent researcher Alexandra Morton has opened another debate about salmon diseases in British Columbia.

Ms. Morton says samples taken from salmon purchased in four Vancouver supermarkets have tested positive for a virus that is suspected of being the "causative agent" of a disease killing Atlantic salmon in European aquaculture operations.

The detection of the piscine reo virus (PRV), which researchers have associated with heart and skeletal muscle inflammation (HSMI) in fish, raises concerns that the disease could be in B.C waters, where it would be a threat to both farmed Atlantic salmon and wild Pacific salmon.

However, Mary Ellen Walling, executive director of the BC Salmon Farmers Association, has questioned the validity of Ms. Morton's tests and both she and government officials say there is no sign of the disease on the West Coast.

"The idea of testing samples from a supermarket is highly unscientific: there's no research design, the fish have no internal organs to sample … there's no chain of custody and there's a lot of opportunity for cross-contamination," she stated in an e-mail.

She added that the industry is concerned about any indication of disease, but fish farmers have been doing their own routine tests "and are seeing no indication of a virus with impacts as described in the release."

Ms. Walling also said that "the research that proposes a linkage between the piscine reo virus and HSMI is tenuous."

Last year, Ms. Morton and researchers at Simon Fraser University, sparked a debate by announcing that Infectious Salmon Anemia virus had been detected in B.C. salmon. The finding has been disputed but is now under intense study.

The presence of HSMI, even if confirmed, would not raise any human health concerns. But the disease has been a serious problem for the aquaculture industry in Norway, where outbreaks have occurred in more than 400 salmon farms since it was first detected in 1999. The disease can stunt growth and weaken muscles, causing mortality rates of up to 20 per cent in infected salmon.

Ms. Morton said the lab tests, which were done by the Atlantic Veterinary College at the University of Prince Edward Island, did not determine the origin of the fresh Atlantic salmon that were purchased at two T&T and two Real Canadian Superstore outlets in Vancouver.

But a spokesman for Loblaw Companies Ltd., which owns Superstore and T&T, confirmed the fish came from a B.C. supplier.

Melanie McNabb, a spokesperson for the Department of Fisheries and Oceans, said in an e-mail that government researchers have not found any sign of HSMI in either wild or farmed B.C. salmon.

"Fisheries and Oceans Canada and the Province of British Columbia have conducted an extensive monitoring and testing program over the years for diseases of concern in both wild and farmed fish; these efforts have revealed no signs of the presence of this disease in British Columbia. And no major mortalities have occurred at BC aquaculture facilities that would have led our fish health professionals to suspect the presence of this disease," she stated.

Craig Ware, a spokesman for Loblaw, said his company is trying to learn more about the issue.

"As relates to this virus, this is definitely the first time we've heard about it in relation to any of the fish that have been sold in our stores," he said on Monday. "Obviously, we take any of these kind of concerns seriously. And so we are looking into it with our suppliers."

Mr. Ware said Loblaw would be staying in touch with DFO on the matter.

"We'll take our lead from them," he said.

The cause of HMSI has not been confirmed, but an international team of researchers at Columbia University's Center for Infection and Immunity, has linked the disease to PRV.

"Our data provide compelling evidence that HSMI is associated with infection with a new reo virus," Gustavo Palacios, first author of the study told the popular journal Science Daily when results were published in July of 2010.

The study identified PRV using DNA sequencing and concluded that "measures must be taken to control PRV not only because it threatens domestic salmon production but also due to the potential for transmission to wild salmon populations."

Another study, published in the April 2012 edition of Veterinary Research, states that the presence of PRV in the hearts of Atlantic salmon, coincides with the development of heart and skeletal muscle inflammation.

"Our results confirm the association between PRV and HSMI and strengthen the hypothesis of PRV being the causative agent of HSMI," the study concluded.

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