Aerial view of fish farming in British Columbia, Canada.
Photo: Adobe Stock.
The peer-reviewed scientific journal 'Reviews in Aquaculture' has published a literature review under the title 'Salmon lice biology, environmental factors, and smolt behavior with implications for the Norwegian salmon farming management system: A critical review'. The result, says the BC Salmon Farmers Association (BCSFA), "further supports that salmon farms are not a driver of sea lice levels on wild salmon."
The study, which reviewed the Norwegian regulatory management of the salmon farming sector based on the so-called traffic light system, has identified overestimates of the effects of sea lice from salmon farms on wild Atlantic salmon and concluded that sea lice infections on farms are not associated with a measurable impact on wild salmon.
"This is an important finding, as it aligns with the research and data we are seeing on sea lice in Canada," said Simon Jones, Emeritus Scientist of Fisheries and Oceans Canada (DFO) and co-author of the published review. "The highly variable relationship between lice levels on wild salmon and salmon aquaculture in BC indicates the need for a greater understanding of all factors affecting the survival of wild salmon."
As the BCSFA explains, sea lice are marine parasites that occur naturally in the ocean and have coexisted with wild salmon for millions of years. "Farm-raised salmon enter the ocean free of sea lice, and the BC Salmon Farmers, under DFO's and First Nations' stringent regulations, diligently practice precautionary management measures to minimize sea lice transmission from farmed to wild salmon," the association claims.
Besides, BC salmon producers continue, newly released 2024 data from the Broughton Archipelago wild juvenile salmonoid monitoring program further support that salmon farms do not impact sea lice levels in wild salmon. As can be seen in the graph below, the variability in the percentage of sea lice in wild Pacific salmon remains unchanged despite the elimination of salmon farms in the area.
Percentage of chum and pink salmon with sea lice (L. salmonis and/or C. clemensi) in the Broughton Archipelago during the spring out-migration. Original graph from Modern Salmon Farming: A Review: Chapter 10 – Sea Lice Management (page 59). The graph has been updated with 2024 data. Original graph adapted from Patanasatienkul et al.
Image: BC Salmon Farmers Association.
Moreover, the average intensity - this is the number of lice per fish - of wild Pacific salmon with sea lice has also remained low over the past 20 years, as the figures in the table below show.
Percentage of chum and pink salmon with sea lice (L. salmonis and/or C. clemensi) and average intensity (# lice/fish) for chum and pink salmon that have lice in the Broughton Archipelago during the spring out-migration. Data 2003-2014 from Patanasatienkul et al., 2015-2024 data from Mainstream Biological Consulting.
Image: BC Salmon Farmers Association.
The findings of this study on the Norwegian traffic light system are in addition to others that the BCSFA has shared before, such as the one conducted by the Canadian Scientific Advisory Secretariat (CSAS) in January 2023, or the long-term data collected annually in the Discovery Islands by registered professional biologists. Both concluded that sea lice in farm-reared salmon do not affect sea lice levels in wild juvenile salmon in British Columbia.
"The continued exaggeration of wild salmon populations declining due to sea lice from salmon farms does not help conservation efforts of wild salmon," said Brian Kingzett, Executive Director of the BC Salmon Farmers Association. "Ongoing research and data support that the salmon farming sector poses minimal risk to wild Pacific salmon, yet government decisions continue to ignore the science and threaten our sector's future," he added.
"BC Salmon Farmers support wild salmon restoration, climate action and food security. It’s time for the federal government to stop using salmon farming as a scapegoat, making unrealistic and unachievable political decisions about our sector, and focus on reliable data and science to address the real issues impacting wild Pacific salmon," Kingzett concluded.
