Wild Salmon Sea Lice and Aquaculture Interaction Welfare

Sea lice from salmon aquaculture farms infest wild juvenile salmon during their ocean migration, causing lesions, stress, and mortality that threatens both wild populations and individual welfare.

Key Facts

Sea lice are naturally occurring parasitic copepods that cause problems at elevated densities near farm sites
Open-net salmon farms create dense sea lice reservoirs that infect passing wild juvenile salmon
Pink salmon smolts are particularly vulnerable during their first marine migration past farm sites in BC
Lice attach to the head and back, causing erosion of the protective mucus layer and skin lesions
High lice burdens cause osmotic stress, secondary infections, and reduced swimming performance
Cleaner fish including wrasse and lumpfish are used in some farms to eat lice without chemicals
In-land recirculating aquaculture systems eliminate sea lice exposure entirely but cost more to operate

Welfare Considerations

Wild juvenile salmon with heavy sea lice burdens experience ongoing tissue damage - the skin erosions caused by feeding lice expose vulnerable tissues and impair the fish's ability to regulate salt and water balance in seawater. Reduced swimming performance increases vulnerability to predation. The welfare harm to wild fish is a direct externality of farm siting near migratory corridors. Closed containment or land-based farming systems eliminate this impact but face economic barriers. Consumer and regulatory pressure for improved farm siting and containment practices is the most direct lever for change.

What You Can Do

Choose salmon from land-based recirculating aquaculture systems that cannot transmit lice to wild fish
Support Pacific Wild and Watershed Watch Salmon Society campaigns for improved farm siting regulations
Advocate for mandatory sea lice monitoring and treatment requirements at open-net aquaculture sites
Choose wild-caught Alaska or Pacific salmon from certified sustainable fisheries when possible
Reduce salmon consumption while aquaculture-wild salmon interaction issues remain inadequately regulated