Deadly European salmon virus found in Pacific stock
Globe and Mail
Salmon conservationists and fish farmers agree more investigation is warranted after two young, wild salmon on British Columbia's central coast were found carrying a highly contagious virus never before detected in the north Pacific Ocean.
Infectious Salmon Anaemia was diagnosed in two of 48 sockeye smolts by the reference laboratory at the Atlantic Veterinary College in Prince Edward Island and reported to the Canadian Food Inspection Agency.
The Simon Fraser University professor who sent the smolts for testing received word on Friday of the positive results, which identify the virus as the same European strain that wiped out about 70 per cent of farmed salmon stocks in Chile.
Fish-population statistician Rick Routledge, wild salmon activist Alexandra Morton and at least one First Nation are calling for an immediate response that involves extensive further examination. They say the test results are further evidence marine-based fish farms should be expunged, one of Ms. Morton's long-time goals.
Representatives for B.C. fish farmers were cautiously concerned for their own stocks, saying they will take proactive measures to get more information, while also noting research suggests wild Pacific salmon are at low risk regarding the virus.
“I have no evidence this disease was killing the fish, just that it's here on the coast and it has implications, potentially enormous ones,” Mr. Routledge said Monday in an interview.
He was “stunned” when tests of the fish, collected for unrelated studies in a lake in Rivers Inlet, came back positive. That means they likely contracted the disease from returning adults, as they completed their four-year salmon life cycle that takes the creatures from B.C. Interior spawning beds out to the ocean and back.
“There's a good chance this disease has been on the coast for several years and we haven't detected it,” he said.
Now that it's shown up, work must be done to definitively identify the source using genetic tracking, Mr. Routledge said. The extent of the infection must be assessed, including which other wild stocks may be carrying the disease, and fish farms must examine more closely whether it has penetrated their pens.
“We have to do what we can to control the source of the infection and at the very least that means treating this as is done in Europe like hoof-and-mouth disease in cattle,” he said. “If it's found, the infected and exposed fish have to be culled.”
There are dozens of both lethal and benign strains of the virus, which at its worst causes a fish's red-blood cell count to drop, produces lesions and sends the fish into a coma before it dies.
Mr. Routledge said Atlantic salmon, grown in B.C. fish farms, are the “only plausible” source of the virus because it's the most likely place that particular strain would be found. Atlantic salmon eggs are the believed cause of Chile's infected stocks in 2007.
That's where the science gets controversial.
More than 4,700 fish have been tested by the regulator for B.C. fish farmers and all have come back negative, although conservationists contend those tests don't meet the gold standard.
Stewart Hawthorn, a director of the B.C. Salmon Farmers Association and managing director with Grieg Seafood based in Campbell River, said nonetheless, the potential discovery of the virus should be investigated further.
“There's so many ‘ifs' and ‘buts' here it's really difficult to be jumping to conclusions,” he said in an interview, noting the association hasn't yet decided its approach because it only learned of the findings from a news release.
He said there's concern because farmers' Atlantic stocks are indeed susceptible to the virus. But he also pointed to a 2003 study in the Journal of Fish Diseases, looking at the resistance of Pacific salmon to the virus, as reason the public shouldn't fear it will harm B.C.’s wild stocks.
Repeated calls to the CFIA were not returned.
Ms. Morton, a fish biologist, said she presented evidence at the Cohen Commission into the decline of the Fraser River sockeye that showed symptoms of the virus have been present in B.C. stocks since 2006. Even so, she said no suspect cases or diagnoses have ever been reported to the CFIA.
In her eyes, that means the government and industry testing to date has been ineffective.
“If we are going to outwit this thing, we cannot do it blindfolded with one hand behind our back,” she said in an interview. “We need to get out there and test everything right now. It's going to be a huge bill.”