B.C.'s salmon farming industry is on high alert after the discovery of a lethal fish virus at one farm on the west coast of Vancouver Island.

The Canadian Food Inspection Agency has quarantined the farm at Dixon Bay, north of Tofino. Mainstream Canada, which runs the operation, says it will destroy its entire stock of 560,000 one-kilo-sized salmon, to prevent the disease from spreading.

The company says Infectious Hematopoietic Necrosis (IHN) was detected during routine testing May 14.

"This is code red," Mainstream spokeswoman Laurie Jensen says.

IHN attacks the fish's blood, and usually kills the animal within a week of exposure. It can kill up to 100 per cent of the populations that become infected, and it spreads rapidly.

"This is not good news for the fish or for the companies." Jenson says. "We will contain this however way we can."

Jensen says boats and visitors have been barred from the site, while the company awaits results from the National Aquatic Animal Health Laboratory which is attempting to culture the virus from farm samples.

But Jensen says an independent lab has already used samples to sequence the virus, which spreads rapidly if not contained.

"So we are just going to depopulate," Jensen says, adding, "we will lose money. It's in the millions. There's a lot of money at stake, but money is not our issue right now."

Jensen says the company will also have to destroy any equipment that can't be disinfected, such as nets.

First outbreak in a decade

This outbreak is the first since IHN swept through three dozen farms a decade ago, when a combination of ignorance and ambivalence allowed it to spread.

Gary Marty, the fish pathologist for the B.C. Ministry of Agriculture, believes Mainstream really has only one option, once the virus is confirmed.

"Get those fish out of the water as soon as you can and avoid the spread to other farms," he says.

Marty concludes the farmed fish were infected by wild salmon which carry IHN, but have developed resistance to the virus. Marty says IHN virus is present in many wild salmon consumed at the dinner table, but is harmless to humans. It is deadly however,  to Atlantic salmon raised in open-net pens in the Pacific ocean.

"So the likelihood that this has any impact on wild salmon is very, very low."

Marty says there is anecdotal evidence the virus has been proliferating in wild salmon populations in the past few years, which may explain why it’s exploded in an outbreak.

The industry isn't waiting for explanations. The B.C. Salmon Farmers Association says all of the companies involved have begun testing for IHN and they're checking to see if any shared suppliers with the Dixon Bay site, which could lead to cross-contamination.

Argument for pulling open-net pens from ocean

But aquaculture critics say the outbreak offers a strong argument for pulling open-net pen salmon farms out of the ocean.

Bonny Glambeck speaks for Friends of Clayoquot Sound, an environmental group that opposes the farms operating in the Sound, which was declared a biosphere reserve by UNESCO more than a decade ago. But Glambeck says the threat of disease also creates economic instability.

"If this disease goes full blown into their other farms and they have to fallow a number of their operations or even leave them fallowed," Glambeck says, "that will mean job lay-offs basically for our region."

The IHN crisis comes just a week after the B.C. Court of Appeal ruled against allowing the certification of a class action lawsuit against open-net fish farms. The legal bid was lead by Bob Chamberlain, chief of the Kwicksutaineuk/Ah-Kwa-Mish First Nation.

"We have these diseases on the farms," Chamberlain says, "and we'd be absolutely foolish to believe there's no opportunity for the disease to go from the farmed fish to our natural stocks."

Mainstream Canada spokesperson Laurie Jensen says the company is expecting the blow-back.

"I’m sure some of our critics will try and make this an issue and they will try and use any kind of unusual activity to create confusion and a food safety issue," Jensen says.  "But it’s just not an issue."

The issue, Jensen says, is to keep a devastating virus from spreading to any of the 13 other sites Mainstream Canada operates in the region of Clayoquot sound, while the rest of the industry watches nervously for success.