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11.02.11

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Phaedra
Photograph courtesy NOAA
OFF THE MENU? Pacific Northwest sockeye are the first victims of infectious salmon anemia on the West Coast.

Into the Wild

An aggressive—and deadly—farmed-fish virus could threaten California's wild-salmon industry

By Eric Johnson

Margot Stiles, a marine scientist with the conservation group Oceana, calls the breaking news of a salmon-killing virus loose in the Pacific Northwest "horrifying." Tobias Aguirre, director of the Santa Cruz–based FishWise, agrees that the virus—infectious salmon anemia (ISA)—could have a "devastating" impact on fisheries in the region and beyond. They both believe the disease could spread to California, a view widely held by ocean ecologists.

Scientists in British Columbia announced two weeks ago that the ISA virus had been discovered in sockeye salmon there. It's the first time the mutant virus has been found in the open ocean of the North American West Coast. Evidence suggests it spread from fish farms in the area.

George Leonard, an aquaculture expert at the Ocean Conservancy's Santa Cruz office, says it was inevitable that the virus would wind up in Canada, where open-net oceanic fish farming is prevalent. And, he says, it's difficult to believe that it will not wind up here as well.

"We've seen ISA spread all around the globe," Leonard says. "It was just a matter of time before it arrived in British Columbia. And I don't doubt that it will spread here—not because of any of the specifics of this particular disease, but because of the basic principles of ecology. A disease that occurs in a fish farm's open net is going to be transferred into the outside world. This is not rocket science."

This disease, however, is particularly dangerous. Infectious salmon anemia had been found in ocean-going salmon for years, but it was not deadly in the wild. The virus morphed into a virulent strain in fish-farming pens in Norway. Stiles says poor aquaculture practices contributed to the virus' mutation.

"These were fish living in densely packed pens, being fed antibiotics—these were not healthy fish," she says. Because there were no predators to pick off the diseased fish, the virus spread rapidly.

When some salmon eggs from Norway were imported to Chile in 2007, the virus came with them and decimated the Chilean salmon-farming industry (though farmed coho did not die), which has not recovered. There are no wild salmon native to Chile, so the disease could not spread beyond the fish farms. But British Columbia is home to one of the most productive wild salmon fisheries in the world.

The Western Fisheries Research Center, a branch of the U.S. Geological Survey, called the recent discovery a "disease emergency." Richard Routledge, the Simon Fraser University sockeye researcher whose team found the virus, said the disease could have "a devastating impact" on farmed and wild salmon, as well as grizzly bears, killer whales and wolves, which feed on salmon. "No country has ever gotten rid of [ISA] once it arrives," Routledge said.

Margot Stiles points out that it's entirely possible that Pacific Northwest sockeye, which have been known to travel as far south as the Mendocino County coast, might come in contact with the salmon that make their homes in the Monterey Bay.

"Their habitats do overlap, so there is a definite possibility that eventually coho salmon will become infected," she says, adding that British Columbia "is really not that far away from California."

FishWise's Aguirre, whose international nonprofit organization includes partners in the aquaculture industry, says the apparent outbreak of ISA is only the most recent problem with open-ocean operations in British Columbia.

"Net-pen production of salmon in B.C. is highly controversial," Aguirre says. "There are many peer-reviewed academic papers illustrating the impacts of farmed salmon on wild salmon, as well as impacts on the entire marine ecosystem."

The sockeye fishery in the area is already in near collapse, with many biologists and activists pointing to aquaculture as the culprit.

Aguirre says that British Columbia "may be ahead of other regions in some of its efforts to limit risks to the natural ecosystem." However, if it is shown that ISA is linked to the salmon farms, there will be intense pressure to put stricter regulations in place. Many advocates, including FishWise, have called on salmon producers to raise their fish in fully enclosed pens.

A law penned by California state senator Joe Simitian, D-Palo Alto, strictly regulated aquaculture in this state in 2006, virtually banning the open-ocean farming of carnivorous fish such as salmon. But George Leonard points out that statewide regulations are not sufficient protection for ocean-going species.

"It's very difficult to put a fence in the ocean," Leonard says. "California took precautions to protect the waters under its control, but it has very little impact on other states or, in this case, other countries."

In the wake of the apparent ISA outbreak, the U.S. Senate approved an amendment calling for an investigation and "a rapid federal response" to the threat.







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