2011-10-17 22:57:00 UTC
VANCOUVER - Wild sockeye salmon from B.C.'s Rivers Inlet have tested
positive for a potentially devastating virus that has never before been
found in the North Pacific.
Infectious Salmon Anemia is a flu-like virus affecting Atlantic salmon that
spreads very quickly and mutates easily, according to Simon Fraser
University fisheries statistician Rick Routledge. The virus detected in
sockeye smolts by the Atlantic Veterinary College in P.E.I. - Canada's ISA
reference lab - is the European strain of ISA.
"The only plausible source of this virus is fish farms," said Routledge.
B.C.'s aquaculture industry has imported more than 30 million Atlantic
salmon eggs over the past 25 years, mainly from Iceland, the United States
and Ireland, according to the Department of Fisheries and Oceans.
"It is described as highly contagious and lethal," said Routledge, who had
underweight fish sent for testing at the suggestion of B.C. salmon biologist
Alexandra Morton. Of the 48 fish sent for testing, two were found to have
Morton had raised concerns about the possibly presence of the virus in B.C.
after seeing Ministry of Agriculture and Lands disease reports describing
"classic" ISA-like lesions in farmed salmon.
B.C. salmon farms conducted 4,726 tissue tests for ISA over the past eight
years and every one came back negative, according to Ian Roberts, a
spokesman for B.C.'s largest salmon farming company, Marine Harvest. Another
65 tests conducted in the past quarter were also negative.
"As far as we know (Marine Harvest) is clean of this disease and we want to
keep it that way," said environmental officer Clare Backman. "Just because
it is present in these Pacific salmon doesn't mean it's a health issue . . .
Pacific salmon are not as affected by ISA as Atlantic salmon."
ISA has been found in wild Atlantic salmon in Nova Scotia's Bay of Fundy, a
fish population that is depressed and on the verge of extinction, Routledge
"There is really no information on the impact it could have on Pacific
sockeye salmon, which is where we found it," he said.
Like the flu in humans, ISA can exist in a relatively benign form and then
mutate into a more deadly version of itself, Routledge said.
The juvenile fish that tested positive were migrating down the Inlet from
Owikeno Lake. The smolts likely contracted the disease from adult spawners
returning to the lake or from their parents, Routledge said.
"That means the virus has been around for several years," he said.
ISA usually is found in Atlantic salmon, though it can also infect herring.
The virus devastated fish farms in Chile in 2007 and 2008, killing millions
of fish and resulting in the closure of both fish farms and processing
plants. Fish farms in Scotland and Norway also have suffered lethal
outbreaks, according to Morton.
"The New York Times reported from Chile that the Chilean aquaculture
industry suffered more than $2 billion in losses," Morton said. An
investigation by scientists from the University of Bergen concluded that
Atlantic salmon eggs imported from Norway to Chile likely were the source of