Lethal Atlantic Salmon Virus Found in Wild Pacific Salmon

VANCOUVER, British Columbia, Canada, October 18, 2011 (ENS) – A deadly and highly contagious marine influenza virus, called infectious salmon anemia, has for the first time been officially documented in salmon in British Columbia.

Infectious salmon anemia has only appeared where salmon are raised in aquaculture. The disease has spread worldwide since first being reported in Norway in 1984. ISA was first reported in Eastern Canada in 1996 and continues to cause problems there.

Wild salmon in a river on the British Columbia coast (Photo by majwick)

The virus was found in two of 48 sockeye smolts collected as part of a long-term study led by Simon Fraser University professor Rick Routledge on the collapse of Rivers Inlet sockeye salmon populations.

Dr. Fred Kibenge of the reference laboratory for infectious salmon anemia at the Atlantic Veterinary College at the University of Prince Edward Island made the diagnosis and notified the Canadian Food Inspection Agency of the positive results for the European strain of ISA virus.

The disease does not affect humans.

Dr. Routledge said, “ISA is a deadly exotic disease which could have devastating impacts on wild salmon and the many species that depend on them throughout much of British Columbia and beyond.”

Biologist Alexandra Morton and fish-population statistician Rick Routledge brief reporters on their research, October 17, 2011 (Photo courtesy SFU)

Routledge and his colleague biologist Alexandra Morton warned at a news conference in Vancouver Monday that ISA is prone to mutating into increasingly virulent forms.

“The combined impacts of this influenza-like virus and the recently identified parvovirus that can suppress the immune system could be particularly deadly,” Routledge warned.

Morton said that to keep the virus from spreading out of control, Atlantic salmon must be “immediately” removed from B.C. salmon farms.

“Loosing a virus as lethal and contagious as ISA into the North Pacific is a cataclysmic biological threat to life,” she said. “The European strain of ISA virus can only have come from the Atlantic salmon farms.”

The European strain of ISA infected Chile via Atlantic salmon eggs in 2007 and became a virulent epidemic killing 70 percent of the country’s farm salmon. Chile does not have wild salmon, but British Columbia does.

“Since then, there have been lethal outbreaks in every important salmon-farming region around the globe, with the exception, or so we thought, of B.C. Now we know for sure that it has hit B.C,” Morton said.

Lesions on the gills of an Atlantic salmon with infectious salmon anemia (Photo courtesy Journal of the American Veterinary Medical Association)

Routledge agrees that the only plausible source for the European strain of ISA virus that he found on B.C.’s central coast is the Atlantic salmon farms.

Rivers Inlet is on the B.C. central coast in the heart of the Great Bear Rainforest. The location is 100 kilometers (60 miles) north of a cluster of Norwegian-owned Atlantic salmon feedlots off Port Hardy and 140 km south of Marine Harvest’s feedlots near Klemtu.

“The potential impact of ISA cannot be taken lightly,” said Routledge. “There must be an immediate response to assess the extent of the outbreak, determine its source, and to eliminate all controllable sources of the virus – even though no country has ever eradicated it once it has arrived.”

Routledge is a fish-population statistician who was a founding member of the Pacific Fisheries Resource Conservation Council.

Morton received an honorary degree from Simon Fraser University for her work linking sea lice infestation in wild salmon to fish farming in the Broughton Archipelago, which has sparked international attention.

The two researchers said that the federal Cohen Commission on the decline of sockeye salmon runs in the Fraser River was told that more than 1,000 cases of ISA-type lesions have been reported on B.C. salmon farms since 2006. Yet no suspect cases or diagnoses of ISA were reported to the Canadian Food Inspection Agency, or to the World Organization for Animal Health.

Salmon farming, B.C. style (Photo courtesy Marine Harvest Canada)

Morton has long urged the Canadian government to close the border to Atlantic salmon eggs as the virus spread in fish farms around the world.

She says the fact that ISA was found in smolts suggests it has been loose in the Pacific for several years.

“Government and industry are clearly not testing effectively,” said Morton. “There needs to be an international volunteer epidemiological team formed right now. No one party can own the data. We have to use everything we know to try and contain this.”

The ISA finding has British Columbia’s salmon farmers concerned, although the BC Salmon Farmers Association says it has not yet been able to review the findings.

Salmon farm on British Columbia coast (Photo by Matt Diederichs)

“Our members are actively following up with the Canadian Food Inspection Agency. The CFIA is reviewing the validity of these publicized but as yet unconfirmed results,” the association said in a statement Monday.

“The results were reportedly found in juvenile sockeye smolts in Rivers Inlet – an area north of most salmon farms,” the association said. “These fish would not have passed aquaculture operations, but our farmers remain concerned about what this means, and how the disease, which is not native to British Columbia, may have been introduced.”

“Farm-raised Atlantic salmon, unlike their Pacific cousins, are susceptible to ISA, so this is a concern for our operations, but much less likely to be an issue for the different Pacific species,” said Stewart Hawthorn, managing director for Grieg Seafood. “If these results are valid, this could be a threat to our business and the communities that rely on our productive industry.”

“Samples from BC’s salmon farms are tested regularly for ISA by our regulator’s fish health departments and have never found a positive case on a farm. Over 4,700 individual fish samples have been assessed and proven to be negative,” said Clare Backman, Sustainability Director for Marine Harvest Canada. “These unconfirmed findings certainly are unexpected, unusual and warrant further investigation,” she said.

Marine Harvest produces one-fifth of the world’s farm-raised salmon at facilities in Norway, Scotland, Canada, Chile, Ireland and the Faroe Islands.

In Canada, Marine Harvest operates salmon farms on the coast of British Columbia and Vancouver Island, where 550 people produce 45,000 metric tonnes of Atlantic salmon each year.