Grieg Seafood announced Wednesday that while tests haven't yet confirmed the presence of infectious haematopoietic necrosis virus at its Ahlstrom Point farm, near Sechelt, B.C., the agency has quarantined the site, home to about 310,000 coho.
That official quarantine follows a voluntary isolation implemented by the company last week after a routine test identified a "low-positive result" for the virus.
Earlier this week, Mainstream Canada announced its Dixon Bay farm, north of Tofino, is now empty after tests confirmed May 14 the presence of the virus, leading to the cull of more than 560,000 young Atlantic salmon.
"Really, it's about saying we're in this stage where we know this virus can affect farm-raised Atlantic salmon and we want to do everything right to make sure that we are not going to be spreading it from there," said Stewart Hawthorn, Grieg Seafood's managing director.
"So the quarantine order is to prevent any risk of any spread from that location."
The food inspection agency notes the virus exists in coastal waters and does not affect human health or food safety but poses a risk to aquatic animal health.
There's little risk to coho salmon, though, because the virus occurs naturally in wild salmon, and coho are native to B.C., said Hawthorn.
"They can carry this virus but not get sick from it."
Hawthorn said a low-positive results means that DNA testing has indicated that a virus might be present.
The company must now confirm whether or not the virus is actually present at the site, and the results of those tests are expected sometime this week, he added.
"We're being very responsible," he said. "We're saying, 'Well, let's assume that this is an IHN positive and we do have a disease that's happening.' That's the worse case it can be."
Grieg Seafood's website said the company holds 21 farm licences, operates a hatchery in Gold River, on Vancouver Island, and a processing facility in Edgmont, located on the Sunshine Coast.
The company said it employs about 130 people.
Provincial government figures show Pacific salmon, including coho, accounted for only six per cent of the salmon farmed in B.C. in 2010.
Ninety-four per cent of the salmon farmed in the province are Atlantic, worth some $470.3 million in that year.