A four-year study headed by Fisheries and Oceans Canada (DFO) has detailed a peculiar phenomenon in British Columbia’s waters: an unknown virus may be killing off large numbers of Fraser sockeye salmon.
In studying B.C.’s renowned Fraser River sockeye, DFO researchers tracked adult salmon in the ocean and river to determine if successful and unsuccessful spawners were physiologically distinguishable prior to reaching the Fraser River.
The results of the study, published in the journal Science, indicate that ocean-tagged salmon “showing a certain gene expression signature” were 13.5 percent more likely to die before spawning than healthy fish, with river-tagged salmon 50 percent more likely to die before spawning.
“This study indicates that disease present in the fish before they enter the river may be impacting spawning success,” said University of British Columbia’s Scott Hinch, a co-author of the study.
The researchers didn’t identify the virus, but suggest it may be related to leukemia or lymphoma.
Biologist and fish farm opponent Alexandra Morton believes it could be salmon leukemia originating from farmed salmon.