Sea lice threaten salmon

Infestations of sea lice at salmon farms on Canada’s west coast are threatening local wild pink salmon populations and could result in their extinction in four years, Canadian researchers said Thursday.

Scientists collected nearly four decades of data on the numbers of pink salmon in rivers along the central coast of British Columbia, comparing the wild populations exposed to salmon farms to those not exposed.

“Overall, populations that were exposed to sea lice-diseased salmon farms are depressed and are declining quickly. This was true even though commercial fishing was closed on these populations,” said Martin Krkosek, a fisheries ecologist from the University of Alberta in Edmonton, whose study appears in the journal Science.

The findings indicate that in certain situations, fish farms can threaten wild fish populations by concentrating and spreading infectious diseases.