Infectious salmon anemia (ISA), a highly contagious flu-like virus that can kill up to 70 percent of fish on infected farms, has been found in the wild off the West Coast of North America for the first time ever, researchers in British Columbia announced on Monday.
Already, experts are warning that the disease, if left unchecked, could devastate Pacific salmon stocks, with one researcher calling ISA a “cataclysmic threat,” and a fisheries expert in Seattle warning of a “disease emergency.”
ISA first emerged in Norway in 1984 when scientists detected a new, more virulent strain of a disease that had long existed in salmon. Experts link the emergence of the new strain to the rapid development of aqualcuture—fish farming—because infected fish shed the virus in packed salmon pens, rather than being consumed by predators in the wild.
“The potential impact of ISA cannot be taken lightly,” said Professor Rick Routledge, whose lab at Simon Fraser University led the study that discovered ISA in the wild. “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.”
Experts suspect the virus jumped to the Pacific Northwest when Atlantic salmon eggs were imported from Europe to be used in the region’s salmon farms.
“The European strain of ISA virus can only have come from the Atlantic salmon farms. European strain ISA infected Chile via Atlantic salmon eggs in 2007,” said Alexandra Morton, another researcher who participated in the study.
According to The New York Times:
The only barrier between the salmon farms and wild fish is a net... No vaccine or treatment exists for infectious salmon anemia.
Researchers at Simon Fraser found the virus on two of 48 wild sockeye salmon being studied as part of ongoing research into the collapse of Rivers Inlet sockeye populations.
The team is calling on the Canadian government to halt the flow of Atlantic salmon eggs to the Canadian salmon farms and for greater testing in the region to determine the extent of ISA infection. They point out that ISA has cost the Chilean salmon industry more than $2 billion since it began ravaging salmon in 2007.
And they note ominously at the end of their release annoucing the discovery that the virus is “prone to mutating into increasingly virulent forms.”