Aquaculture

Salmon Sea Lice Welfare During Treatment

Medical and mechanical sea lice treatments cause acute stress to salmon and require welfare-conscious application protocols.

Key Facts

Sea lice (Lepeophtheirus salmonis) cause skin lesions, anaemia and stress in farmed salmon
Chemical bath treatments involve crowding fish in high concentrations of hydrogen peroxide or azamethiphos
Mechanical removal using thermolicer (warm water) and freshwater treatment causes crowding stress
Treatment frequency has increased as lice resistance to chemicals has developed
Biological control using cleaner fish can supplement but not replace other treatments in most systems

Welfare Considerations

Sea lice treatment events represent peaks of acute welfare compromise in salmon aquaculture. Crowding during treatment causes severe physiological stress regardless of the treatment modality. Reducing treatment frequency through prevention-focused integrated pest management, and minimising crowding duration during necessary treatments, are key welfare priorities.

What You Can Do

Support certification schemes requiring integrated lice management and treatment welfare protocols
Choose salmon from farms with documented low lice burden and minimal treatment frequency
Advocate for regulatory requirements for welfare assessment of treatment methods
Follow Aquaculture Stewardship Council sea lice standard development