Sea Lice in Salmon Farming: Welfare and Ecological Impacts

Sea lice infestations in salmon farms cause severe welfare harm and threaten wild salmon populations.

Key Facts

Sea lice are ectoparasitic crustaceans that feed on salmon skin and blood
Infestations cause skin lesions, secondary infections, and anaemia in farmed salmon
Treatments including hydrogen peroxide and emamectin benzoate have resistance developing
Norwegian salmon farms spent over 500 million euros on sea lice treatments in 2019
Wild salmon smolts migrating past farm cages can be overwhelmed by lice from farmed fish

Welfare Considerations

Sea lice infestations cause progressive welfare deterioration in affected fish. Lesions from feeding provide entry points for bacterial and fungal infection. Heavy infestations cause stress, immune suppression, and lethargy. Treatment procedures including bath treatments cause handling stress and some mortality. Chemical treatments that escape into the marine environment affect wild crustaceans. The cycle of infestation and treatment represents chronic welfare compromise in conventional sea cage salmon farming.

What You Can Do

Choose ASC-certified salmon that requires sea lice management below welfare thresholds
Support Compassion in World Farming campaigns for improved salmon welfare standards
Advocate for closed containment salmon farming that eliminates sea lice transmission
Reduce farmed salmon consumption or choose land-based RAS farmed alternatives
Support research into biological sea lice control including cleaner fish welfare standards