Salmon Lice: Welfare Impact and Treatment Science 2025

Key Welfare Facts

Sea lice infestations cause skin lesions, muscle damage, immune compromise, and chronic stress in farmed salmon.
Caligus and Lepeophtheirus parasites cause dose-dependent welfare harm that scales with louse burden.
Medicinal bath treatments using emamectin benzoate and hydrogen peroxide cause acute stress during treatment.
Non-medicinal mechanical removal using thermolicer and hydrolicer systems cause welfare compromise from crowding.
Biological control using wrasse cleaner fish raises its own welfare concerns addressed in separate guidance.
Integrated pest management combining cleaner fish, fallowing, and medication aims to minimise total welfare burden.

Welfare Assessment

Sea lice welfare management presents complex trade-offs between treatment welfare impacts and parasite welfare impacts. Supporting certification schemes that require integrated pest management approaches and monitoring of louse burdens advances welfare science in this contested area.

What You Can Do

Choose salmon from certified operations with documented integrated lice management programmes
Support research into welfare-positive lice prevention and treatment alternatives
Advocate for mandatory lice burden reporting and treatment welfare impact assessment
Engage with retailers about salmon supplier lice management welfare standards