Read this report from The New York Times on the discovery of deadly Infectious Salmon Anemia virus in wild coho in a tributary of the Fraser River.

“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.” (October 28, 2011)

Read full article: http://www.nytimes.com/2011/10/29/science/pacific-salmon-virus-raises-worries-about-industry.html?_r=1