Ivan Alvarado/Reuters
Workers processing farmed salmon at a plant in Puerto Ibañez, Chile. Salmon are farmed in vast netted pens in much of the world.
SEATTLE — Like mariners scanning the horizon from the crow's nest, scientists have for years been on the lookout in the Pacific Northwest for signs that a dreaded salmon-killing disease, scourge to farmed salmon in other parts of the world, has arrived here, threatening some of the world's richest wild salmon habitats. Most say there is no evidence.
But for years, a biologist in Canada named Alexandra Morton — regarded by some as a visionary Cassandra, by others as a misguided prophet of doom — has said definitively and unquestionably that they are wrong. Wild Pacific salmon, she has said, are testing positive for a European strain of the virus that causes the disease, infectious salmon anemia, or I.S.A.
The virus, which has struck farmed salmon populations in Chile, among other places, is not harmful to humans who eat the fish, but could potentially pose grave threats in a part of the world where salmon plays a huge role in local economies and ecosystems. If the virus, which is in the influenza family, mutates into a virulent Pacific strain in the crowded fish farms in British Columbia, where wild and farmed salmon are sometimes in proximity, fish populations on both sides of the farm/wild divide, Ms. Morton believes, could be devastated.
"It's an uncomfortable truth," she said.
But scientists and government testing groups in Canada and the United States have said repeatedly over several years that Ms. Morton's findings were not sufficient to sound an alarm, and that the risks to wild salmon, even in the event of a fish-farm outbreak, are unclear. After rounds of government hearings and millions of dollars spent on research, the two sides are in an increasingly bitter standoff.
"We're trying to re-create the situation that she's saying is out there, and to date we cannot re-create the results," said Dr. Penny Greenwood, national manager of the domestic disease control program at Canadian Food Inspection Agency.
Now, Ms. Morton has new test results that she said are positive for the infectious salmon anemia virus — though not necessarily the disease — in farmed salmon she bought at a fish market in Vancouver late last year. At the same time, the biggest effort ever on the American side of the border to find the virus is shifting into high gear, with fish samples arriving in labs in Idaho, Alaska and here in Washington State.
"I think we're probably pretty close to having a definitive answer," said Martin Krkosek, an assistant professor of ecology and evolutionary biology at the University of Toronto.
The stakes are enormous, and not least for reputations. Salmon, in all their varied and usually pink-hued glory, have been an ecological anchor from Alaska to Oregon, intertwined with the region's culture and economy since long before the arrival of Lewis and Clark.
The search for the virus raises questions that have swirled through commercial fishing and oceanography: Has the growth of open-ocean fish farming over the last three decades and the vast netted pens of Atlantic salmon from Chile to Maine and Norway to Canada created a reliable source of sustainable, inexpensive protein? Or, as critics contend, are the farms unsustainable because they pollute the seabed and because the close confinement of the fish raises the risk of disease?
Salmon farmers say that the broader controversy over aquatic farming has informed the narrower discussion of the salmon disease, and that Ms. Morton in particular has been out to get them, whether a virus is involved or not.
Adding further fuel — or at least, smoke — to the fire is a new documentary that accuses the Canadian government of deliberately covering up evidence that would support Ms. Morton's conclusions. A Web site has since emerged that tries to debunk to the documentary.
"She says one thing, everybody else says something different, and therefore, in her view they're all in collusion, and not doing a good job," Ian Roberts, a spokesman for Marine Harvest Canada, the biggest salmon farming operation in British Columbia, said of Ms. Morton. He said his industry had sent upward of 8,000 samples for testing in recent years, without a single confirmed finding of the I.S.A. And he said the survival rate at his company's salmon farms was better than 90 percent.
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