Salmon Welfare and Sea Lice Treatment Stress

Sea lice infestations are a major welfare and production problem in Atlantic salmon farming. Treatments including fresh water baths, hydrogen peroxide, and mechanical removal cause significant acute stress and injury to treated fish.

Key Facts

Sea lice are parasitic copepods that feed on salmon skin and mucus
Infestations cause open wounds, secondary infection, and reduced immune function
Mechanical delousing (Hydrolicer) removes lice by high-pressure water and causes scale loss and injury
Thermal treatments using heated water (Thermolicer) cause thermal stress and internal damage
Biological control using cleaner fish (wrasse and lumpsucker) is welfare-positive but has scalability limits

Welfare Considerations

Treatment-associated mortality and injury from mechanical and thermal delousing represents significant welfare harm inflicted directly to reduce the welfare harm of sea lice infestation. The welfare trade-off is genuine and complex. Fish that survive delousing with injuries face infection risk and chronic stress during recovery. Cleaner fish that are understocked or injured themselves represent a welfare concern within the welfare solution. Integrated pest management that reduces treatment frequency is the welfare-optimal approach.

What You Can Do

Support Aquatic Life Institute campaigns for sea lice integrated pest management standards
Advocate for mandatory welfare monitoring of treatment-associated mortality at Scottish salmon farms
Choose salmon from farms certified to reduce lice treatment frequency
Donate to research into cleaner fish welfare and sea lice vaccine development
Engage with Marine Scotland Aquaculture Policy consultation on sea lice treatment welfare standards