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Virus in Pacific Salmon Raises Worries About Industry

From the NEW YORK TIMES
By WILLIAM YARDLEY
Oct 29, 2011

Advocates for wild salmon said Friday that a deadly virus had been detected again in a Pacific salmon in British Columbia, but it was not clear if it would prove lethal to the fish population.

The finding, like one involving two juvenile wild sockeye salmon in British Columbia, poses questions for the viability of salmon fisheries in Canada and the United States. Scientists have expressed concern about the emergence of the virus while raising questions about complications, including scientific doubts about the quality of the tests.

Isavirus_virionIn its active state, the virus, infectious salmon anemia, has devastated Atlantic salmon populations in fish farms in Chile and elsewhere. Salmon advocates have long worried that the virus could spread to wild populations, but it not clear whether Pacific salmon are equally susceptible.

In documents released Friday, an adult coho salmon supplied by salmon advocates to a prominent laboratory showed signs of carrying the disease. That fish was reported to have been found in a tributary of the Fraser River, a critical salmon run for fishermen in Canada and the United States.

Last week, researchers from Simon Fraser University in British Columbia and elsewhere said that they had discovered the virus in 2 of 48 juvenile fish collected as part of a study of sockeye salmon in Rivers Inlet, on the central coast of British Columbia. The study was undertaken after scientists observed a decline in the number of young sockeye.

Such a virus could have a deep impact on the survival of salmon in the Pacific Northwest. Some scientists have suggested that the virus had spread from British Columbia’s aquaculture industry, which has imported millions of Atlantic salmon eggs over the last 25 years.

Salmon farms and wild fish are separated only by a net, many have noted. No treatment exists for the virus, which does not spread to humans, scientists say.

The crowded conditions of salmon farms are thought to abet the spread of the virus.

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