The Canadian Food Inspection Agency has tested more than 4,000 samples from wild salmon on the West Coast without getting any positive results for three fish diseases that have raised alarms in British Columbia.
In a statement Tuesday, the CFIA said all the samples collected in B.C., as part of a major new disease-surveillance project, have tested negative for infectious salmon anemia (ISA).
The 4,175 wild salmon samples were also negative for infectious hematopoietic necrosis (IHN) and infectious pancreatic necrosis (IPN).
ISA has been on the radar in B.C. since independent researcher Alexandra Morton and Simon Fraser University reported in 2011 that they had found evidence of the virus in wild Pacific salmon for the first time.
That rang alarm bells, raising fears that major outbreaks of a disease associated with Atlantic salmon could have spread to Canada's Pacific coast.
But Nathalie Bruneau, national manager of aquatic surveillance and epidemiology for CFIA, says a thorough and exhaustive research effort has so far failed to find proof of ISA in B.C. salmon.
"As of today what we're saying … [is] we haven't found it. We're going to keep looking," said Dr. Bruneau.
She said the results come from the first year of a two-year project that will be completed in 2014.
Dr. Bruneau said it is too soon to say definitively that ISA is not on the West Coast.
She said the CFIA plans to collect and test another 5,000 samples this year, and when those results are in "we're going to assess everything and make a statement about what we believe is the status for this disease in British Columbia."
The Washington State Department of Fish and Wildlife reported last month that tests of 900 salmon had come back negative for ISA.
But Ms. Morton said she has continued to get positive hits for ISA in samples that she and volunteers collected over the past two years. She said those tests have been confirmed by seven different labs and called in to question the CFIA's research.
"What the seven labs found are segments of the virus," she said. "We definitely have ISA virus here. You can't have seven labs getting big chunks of the sequence and not have it here."
Ms. Morton has long blamed fish farms for spreading sea lice and diseases to wild stocks.
But Mary Ellen Walling, executive director of the BC Salmon Farmers Association, said the growing body of scientific evidence does not support that view.
She said her industry has had an intensive testing regime in place for years on farmed salmon and is glad to see the CFIA now testing wild fish.
"It's important for this wild fish surveillance to be done," said Ms. Walling. "If they were to see any trace of disease, they would be able to make some rapid decisions about managing it."
Fish farms in B.C. raise mostly Atlantic salmon. ISA first emerged in farmed Atlantic salmon in Norway almost 30 years ago and has since caused disease outbreaks in several regions, including on Canada's East Coast and in Chile.
"The oceans are open systems and what we want to ensure is that we don't have any role in bringing any kind of disease in," Ms. Walling said.
While the CFIA research adds an important piece to the puzzle, the definitive work on fish disease is expected to come from a massive study just getting under way. Headed by Dr. Brian Riddell, President and CEO of the Pacific Salmon Foundation, and Dr. Kristi Miller, head of molecular genetics for Fisheries and Oceans Canada, the project will screen thousands of salmon for 45 different disease microbes.
Dr. Riddell said the study will do tests to a level of sensitivity not seen before in fish studies in Canada.