Salmon Lice Welfare and Aquaculture Management

Sea lice infestations on farmed Atlantic salmon cause serious welfare harm and threaten wild salmon populations through lice transmission. Management approaches have significant welfare implications.

Key Facts

Salmon lice (Lepeophtheirus salmonis) are parasitic copepods that graze on salmon skin and mucus
Severe infestations cause lesions, stress, and physiological compromise in farmed fish
Farmed salmon near wild migration routes can amplify lice loads on wild juvenile salmon
Chemical treatments including emamectin benzoate have resistance concerns and environmental impacts
Biological control using cleaner wrasse and lumpfish is growing but has welfare implications for these fish
Closed containment systems (RAS) prevent lice infection but require high energy input

Welfare Considerations

Salmon lice welfare involves both the farmed salmon hosts and the cleaner fish used to control them. Severe lice infestations cause skin damage, haemorrhage, and stress in salmon - a serious welfare harm. Cleaner fish including wrasse captured from the wild or farmed lumpfish are used to eat lice from salmon - these are sentient fish whose welfare as 'tools' is rarely considered. Wrasse mortality rates in salmon farms are very high, suggesting poor welfare outcomes. Chemical treatments cause acute stress to treated fish. Closed containment systems prevent lice entirely and represent the most welfare-complete solution, albeit with significant economic costs.

What You Can Do

Choose RSPCA Assured salmon that sets lice management welfare standards
Advocate for welfare standards for cleaner fish used in salmon aquaculture
Support investment in closed containment salmon farming research
Ask producers about their cleaner fish welfare standards and sourcing
Back independent research on the welfare implications of different lice management strategies