Canadian government officials said Tuesday they have found no signs of a potentially deadly infectious salmon virus in British Columbia.

Researchers with Simon Fraser University in British Columbia announced last month they had detected infectious salmon anemia, or ISA, in two wild juvenile Pacific sockeye collected from the province's central coast, prompting fears the influenzalike virus could wreck wild salmon populations in the Pacific Northwest.

In follow-up tests, Canadian government researchers said they found nothing that would support the idea that ISA existed along the Pacific Coast.

"There's no evidence that (the virus) occurs in fish off the waters of British Columbia," Dr. Cornelius Kiley, a veterinarian with the Canadian Food Inspection Agency said during a news conference Tuesday. He added: "It is not known to occur at this moment of time in the North Pacific."

The Canadian officials said their results were consistent with independent testing conducted by a lab in Norway. That lab found one positive reading among multiple tests but also noted the sample was poor and the results could not be reproduced, said Peter Wright, national manager for the Research and Diagnostic Laboratory System with Fisheries and Oceans Canada.

But the Norwegian researcher who conducted those tests offered a completely different interpretation of his results.

"Our results are not conclusive, but do suggest ... that an ISA virus is present in wild populations of O. nerka (Pacific sockeye)," Dr. Are Nylund, a professor of biology at the University of Bergen, wrote in an email exchange with The Seattle Times.

"The results do not tell anything about the virulence of this ISA virus or if such a virus represents a danger for the wild and farmed populations of salmon in western pacific."

Wright said the Canadian officials were "erring on the side of caution" by announcing that no virus could be confirmed.

"If something is so badly degraded that you can't measure it, you can't say with any extreme confidence that it's positive or negative," he said.

Officials are continuing to test samples for the salmon virus, which has affected Atlantic salmon fish farms in Chile, Maine, New Brunswick and other areas. It does not affect humans.

The news that Canadian officials had not confirmed the virus was welcomed by B.C.'s salmon farmers.

"This is a significant result for everyone involved: researchers, regulators, wild salmon advocates, salmon farmers and our coastal communities," Mary Ellen Walling, executive director of the B.C. Salmon Farmers Association, said in a statement. She added: "We hope this update will allay those concerns."

But Rick Routledge, the researcher with Simon Fraser University who initially announced the detection of the salmon virus in October, said Tuesday that the one positive reading by an independent laboratory in Norway shouldn't be dismissed.

"The evidence is not as strong as it would have been had he been able to repeat it," Routledge said. "Given that he did get a positive reading once, from a degraded sample, I don't feel comfortable with the notion that you could dismiss that out of hand. I hope that further sampling and testing would continue."

The virus was initially detected in two of 48 juvenile sockeye salmon collected as part of a long-term study of sockeye salmon led by Routledge.

Fred Kibenge, of the Atlantic Veterinary College at the University of Prince Edward Island, confirmed the presence of the virus in two fish.

The report last month that it had been detected in wild Pacific salmon for the first time on the West Coast, prompted concern by state and federal officials in the U.S.

U.S. senators have called for increasing surveillance, testing and research. Maria Cantwell, a Democrat from Washington, and Republican Lisa Murkowski and Democrat Mark Begich — both from Alaska — have also called for the National Oceanic and Atmospheric Administration to run its own tests on the salmon.

Meanwhile, Washington state officials have been working in recent weeks with U.S. agencies, tribes and Alaska state officials on a plan to sample additional fish for the virus.

"This is not the final end of the issue," said James Winton, who directs the fish health section of the U.S. Geological Survey's Western Fisheries Research Center in Seattle. He said he had not yet reviewed the details of the Canadians tests.

Seattle Times environment reporter Craig Welch

added to this report.