New peer-reviewed study finds no link between BC salmon farms and sea lice levels in wild fish.
A new scientific study published in the Journal of Fish Diseases has found no evidence that salmon farms in British Columbia are the primary driver of sea lice infestations in wild Pacific salmon, challenging a long-standing claim made by critics of aquaculture in the region.
The research, conducted over eight years between 2017 and 2024, tracked sea lice prevalence on juvenile pink and chum salmon in the Discovery Islands — an area where all salmon farms were removed by 2022 following a federal phase-out order.
According to the authors, 2024 saw some of the highest sea lice levels recorded during the study period, despite the absence of active salmon farms. “These findings demonstrate that the evidence does not support the narrative of ‘no farms means no sea lice’,” said Lance Stewardson, director of Mainstream Biological Consulting and one of the study’s authors.
The research was carried out in partnership with local First Nations stewardship staff and covered multiple coastal zones, including the Broughton Archipelago. A similar pattern of lice variability was observed in both regions, including in areas without farms.
“This long-term monitoring shows that significant natural sources of sea lice exist,” said Stewardson. “Our findings disprove the claim that salmon farms are the sole driver of sea lice on wild Pacific salmon in the near-shore environment and underscore the need for continued monitoring.”
The study’s conclusions are consistent with a 2022 Science Response published by the Canadian Science Advisory Secretariat (CSAS), which found no statistical correlation between sea lice counts on wild and farmed salmon. The findings also align with a broader literature review published in 2023, which found that the impact of salmon farms on wild sea lice levels had been frequently overstated.
The full paper is available online via Wiley: https://onlinelibrary.wiley.com/doi/10.1111/jfd.14136.