Infectious salmon anemia, a virus that has triggered devastating disease outbreaks in stocks of farmed Atlantic salmon around the world, appears to have been in British Columbia wild salmon for at least 25 years, the Cohen commission of inquiry has heard.
The ISA virus – or a new variation of it – has been found repeatedly in samples of wild sockeye and pink salmon, as well as in samples of farmed chinook taken from one West Coast aquaculture operation.
That revelatory evidence was given on Thursday, by Kristi Miller, head of molecular genetics at the federal Pacific Biological Station in Nanaimo.
"I clearly believe that there is a virus here that is very similar to the ISA virus in Europe … [but]we have not established that it causes disease," said Dr. Miller.
She was one of four experts on ISA called to testify about a recent series of conflicting test results that have raised questions about whether the virus is present on the West Coast or not.
In October, sockeye salmon collected by Simon Fraser University researchers were tested at an East Coast lab and several samples were found positive for ISA. But follow-up testing by the Department of Fisheries and Oceans and the Canadian Food Inspection Agency failed to replicate the results. As other labs got into the picture, some got positive results, while others didn't.
Intrigued by the SFU discovery, Dr. Miller said she launched her own research effort and has concluded that the ISA virus, or something much like it, is present in both wild and farmed salmon in B.C.
Fred Kibenge, chair of the department of pathology and microbiology at the University of Prince Edward Island, which did the SFU testing, agreed with Dr. Miller's assessment.
"In my view … I think there's evidence there are ISAV sequences in fish samples from B.C.," Dr. Kibenge said. "I think the result is credible. Now, whether it's ISA or ISA-virus-like, that requires some work."
Dr. Miller said her tests found a virus that is 95-per-cent similar to the European strain of ISA, which has infected farmed Atlantic salmon in Norway, Scotland, Atlantic Canada and Chile.
She said when her tests detected ISA in fish collected this year, she went back into the laboratory's storage lockers and pulled out samples of fish from as far back as 1986 – and found ISA there too, showing the virus has been present at least 25 years.
Dr. Miller said the ISA virus has now been confirmed in numerous wild fish, and in chinook samples provided by Creative Salmon, a fish farm on Vancouver Island.
Dr. Miller said Creative was the only fish farm that co-operated with her research efforts, and she had not been able to get samples from other farms in B.C.
"They did not want their samples to be tested," she said of the farms, which mostly raise Atlantic salmon.
The ISA disease can be lethal to Atlantic salmon, but lab tests suggest it does not kill Pacific salmon.
However, a report by Brad Davis, a postdoctoral fellow working with Dr. Miller, indicates that fish with the virus react in a way that "suggests that the virus is causing enough damage to elicit a strong response in the salmon. … Therefore, we cannot at this point assume that this virus does not cause disease in these fish."
The panel of ISA experts included Are Nylund, a professor at the University of Bergen who was testifying by video link from Norway, and Nellie Gagné, a molecular biology scientist with a DFO testing lab in Moncton.
The panel members all agreed that the conflicting results between labs could be the result of different techniques.
Dr. Nylund said he is not convinced by Dr.Miller's work, which was completed just last week.
"I don't think we have seen … hard evidence," he said.
Ms. Gagné said the ISA virus was first detected on the East Coast in 1990, and research showed it was a different strain from the European virus.
"It could be we are really looking at another [third kind of]ISA," she said.