Mainstream Canada announced Friday afternoon that the agency had quarantined a second of its farms, the latest at Bawden Point off the west coast of Vancouver Island, north of Tofino, B.C., after tests results indicated a "low-positive" result for the haematopoietic necrosis virus, known as IHN.
The first quarantine took place last week, also at a Mainstream farm north of Tofino, and forced the company to cull more than 560,000 juvenile Atlantic salmon.
The other company to face a quarantine over the possible presence of the virus was Grieg Seafood, which also announced Friday afternoon that independent laboratory tests for IHN at a farm on the Sunshine Coast have now come back negative.
"There has been that weak positive at that second farm, Bawden, and it requires additional testing," said Mary Ellen Walling, executive director of the BC Salmon Farmers Association. "They're not currently seeing any related mortalities."
But anti-salmon farming activist Alexandra Morton said she has no reason to trust the companies and wants to see the test results, the actual sequence data, and the strain of IHN.
If the companies don't want to give her samples of the fish, then they can give them to First Nations for testing, she said.
"They have a serious problem on their hands," she said. "I think they're out of control."
According to the food inspection agency, the virus does not pose a risk to human health and is found in wild fish in the Pacific.
The virus can cause death in young finfish raised in freshwater hatcheries, juveniles recently introduced to sea water and older finfish raised in sea water, states the agency on its website.
Susceptible to infection are 20 species found in the natural environment, including pink, chum, coho, sockeye and Atlantic salmon, as well as Pacific herring, the agency adds.
According to the agency, the virus is spread by contaminated equipment and contaminated water, and while there are no treatments available, vaccines are available to prevent the disease.
If a positive result comes back for the virus on their farm, Mainstream Canada still plans to harvest Atlantic salmon from Bawden Point because the fish will be ready for market and will not be harmful to humans.
Meantime, Walling said test results for IHN have come back negative for 30 salmon farms, and another 21 samples are awaiting processing.
She said the Department of Fisheries and Oceans has also sampled farms as part of its routine testing, and those samples came back as negative.
According to B.C.'s Ministry of Environment, the province's salmon farming industry is the fourth largest producer of farmed salmon in the world, and in 2009, 18 companies operated on 131 sites.
Ninety-four per cent of the salmon farmed in the province are Atlantic salmon, with the remaining six per cent made up of Pacific salmon.
The provincial government reported that in 2010, the value of Atlantic farmed salmon was estimated at $470.3 million.