A virus related to leukemia and lymphoma may have been responsible for the 2009 drop in Fraser River sockeye salmon, a new study published in the journal Science suggests.
Declining since the 1990s, the Fraser sockeye runs had attracted only about a million spawning fish in 2009, instead of the 10 million expected. Although the 2010 run was an almost unprecedented 30 million, Canadian Prime Minister Stephen Harper had already appointed a judicial inquiry, the Vancouver Sunreported.
Some scientists theorized that the 2010 run was boosted by ash from a 2008 volcanic eruption in Alaska that may have sparked the growth of plankton by "fertilizing" the sea, the Vancouver Sun story said. But this does not take the runs out of danger, given practices such as overfishing, mismanagement and fish farm–borne sea lice, the newspaper added.
And now scientists studying the 2009 phenomenon have concluded that the most likely cause was a leukemia- or lymphoma-type virus that infected the salmon while they were still out at sea.
“Dead fish swimming,” is how one of the study’s co-authors, Scott Hinch from the University of British Columbia, put it to the Vancouver Sun.
“There is no doubt there is some form of pathogen involved,” Hinch said.
The group also said a genetic flaw may make them more vulnerable to deadly viral infections, Reuters reported.