Salmon Sea Lice: Welfare and Management

Sea lice are the leading welfare concern in Atlantic salmon farming, causing significant suffering and requiring intensive management intervention.

Key Facts

Sea lice are parasitic copepods that feed on the skin and mucus of salmon
Infestations cause open lesions, secondary infections, stress, and mortality in severe cases
Current treatments include chemical, biological, and physical methods, each with welfare implications
Genetic resistance to chemical treatments is increasing, requiring integrated management approaches

Welfare Considerations

Sea lice infestations in farmed salmon cause progressive welfare deterioration as parasite numbers increase. Lesions at feeding sites become infected, causing chronic pain and immune system challenge. Treatment methods themselves impose welfare costs — chemical bath treatments require confinement and handling, mechanical removal causes stress and physical damage, and freshwater treatments are stressful for saltwater-adapted fish. Managing sea lice sustainably requires preventive approaches including site selection, fallowing, snorkel nets to avoid surface lice, and biological control through cleaner fish — all while maintaining the welfare of both salmon and cleaner fish species.

What You Can Do

Choose salmon certified by schemes with verified lice management welfare standards
Support investment in non-chemical sea lice prevention methods
Advocate for stronger regulations on permitted lice levels in salmon farming
Encourage transparency in reporting of lice levels and treatment methods by producers