Fish farm disease ‘spreading to wild fish’, study finds
Tenacibaculosis, a bacterial disease which causes skin and fin ulcers, has been found in wild Chinook salmon in British Columbia for the first time.
The disease is reasonably common in farmed salmon, but a new study marks the first confirmed case in wild-caught fish.
The research has been led by the University of British Columbia (UBC) , the Pacific Salmon Foundation, and others.
The scientists say they caught Chinook salmon in BC’s Barkley Sound, on the west coast of Vancouver Island, as part of a separate study on the impacts of caught and released salmon.
Of the 99 fish sampled, 16% showed signs of tenacibaculosis, with high associated mortality.
Dr. Emiliano Di Cicco, a fish health researcher with the Pacific Salmon Foundation and lead author of the study, said: “This is the first time tenacibaculosis has been diagnosed in wild-caught fish, providing empirical evidence that Tenacibaculum bacteria can negatively affect wild fish health and contribute to disease burden in B.C. wild salmon.”
Diagnosing marine diseases in wild fish is inherently difficult, he added. In the ocean, sick fish rarely survive long enough to be observed.
“Once a wild fish gets sick, it’s often caught by a predator quickly, or it becomes too weak to feed and eventually starves. That’s why finding a sick fish in the wild is so difficult,” said Dr. Di Cicco.
Katie Zinn, from UBC’s Pacific Salmon Ecology and Conservation Lab, and co-author of the study, said: “We spend enormous effort trying to understand why wild salmon die in the ocean. This study gives us one of the clearest pieces of evidence that links bacterial disease to mortality in wild Pacific salmon.”
Tenacibaculosis is one of the most common diseases in farmed Atlantic salmon and trout raised in open-net pens in British Columbia, and a leading cause of farm mortality.
It has also been found in farmed and hatchery-origin Pacific salmon in California, Chile, New Zealand, and Alaska.
Common symptoms include lethargy, loss of balance, abnormal swimming behaviour, skin, fins and oral ulcers, and high mortality.
The news is certain to fuel the debate of whether the Canadian government should continue with its policy of closing open pen salmon farms in BC.
First report of tenacibaculosis in wild-caught Pacific salmon, De Cicco et al, Scientific Reports June 2026
Why not try these links to see what our Fish Farmer AI can tell you.
(Please note this is an experimental service)
You May Also Like
© 2026 Fish Farmer.