Salmon Lice and Aquaculture Welfare

Sea lice infestations in salmon farms cause severe suffering to millions of fish and are one of the most significant welfare challenges in aquaculture.

Key Facts

Sea lice attach to salmon skin and mucus, feeding on tissue and blood
Severe infestations cause open wounds, fin damage, and can expose the skull
Norwegian salmon farms treat lice using hydrogen peroxide baths and mechanical delousing
Mechanical delousing involves flushing fish through rotating drums — causing scale loss and injury
Cleaner fish like wrasse are used to eat lice but have poor welfare in aquaculture themselves

Welfare Considerations

Sea lice infestations are intensely painful. Lice attachment sites show inflammatory responses and fish show pain-avoidance behaviors. Chemical treatments cause their own suffering — hydrogen peroxide baths cause respiratory distress and tissue damage. Thermal treatments burn and stress fish. Mechanical delousing causes scale loss and physical injury. The use of cleaner fish adds another layer of welfare concern, as wrasse have poor survival rates in salmon farm conditions. Developing enclosed land-based aquaculture systems that prevent lice exposure is the most promising long-term solution.

What You Can Do

Support development and adoption of land-based closed-containment salmon farming
Advocate for lice treatment methods that prioritize fish welfare
Choose salmon from farms with independent welfare certification
Support research into biological lice control that avoids painful treatments