A newly published study has added to the growing body of evidence that the removal of salmon farms in British Columbia’s Broughton Archipelago has had no measurable impact on sea lice levels among wild salmon.

The paper, published in Diseases of Aquatic Organisms, analyzed data from both salmon farms and field studies of wild salmon captured between 2016 – when farms were still operating in the region – through 2024, after most operations had been removed. Researchers found no correlation between the reduction of farms and sea lice infestations on wild salmon.

The Broughton Archipelago has been the focus of 25 years of intensive research into interactions between farmed and wild salmon. The recent phase-out of aquaculture sites provided an opportunity to further test long-standing assumptions.

“In B.C., the proximity of juvenile salmon migratory routes to open-net pen salmon aquaculture sites led to an assumption that most, if not all, sea lice infesting the juvenile salmon originate from infestations on the farmed salmon,” the study notes. The findings, however, challenge this assumption and highlight the complexity of sea lice dynamics in the region.