Sea Lice Treatment Advances in Salmon Aquaculture

Sea lice are the primary parasite challenge in salmon farming, and the welfare of both infested fish and the cleaner fish used to control them deserves careful consideration.

Key Facts

Sea lice infestations cause chronic skin damage, stress, and immune suppression in salmon
Cleaner fish (wrasse and lumpfish) are used to eat lice but face high mortality and welfare challenges
Thermal and mechanical delousing treatments cause significant acute stress and mortality
Resistance to chemical treatments is widespread in sea lice populations globally
Genetic selection for lice-resistant salmon strains is an emerging preventive approach

Welfare Considerations

Sea lice management represents a welfare-on-welfare dilemma: heavy infestations cause chronic suffering in salmon, but treatment methods often cause acute welfare harm. Thermal delousing exposes fish to hot water (30-34C), causing heat shock and mortality. Mechanical brushing physically damages skin. Chemical treatments raise resistance and environmental concerns. Cleaner fish used as biological control face their own severe welfare challenges — wrasse have complex behavioral needs incompatible with intensive farming conditions. Integrated pest management combining genetic resistance, improved containment, and higher-welfare treatment protocols offers the most sustainable path.

What You Can Do

Choose salmon certified under standards that address sea lice welfare management
Support research into sea lice-resistant salmon strains and vaccine development
Advocate for welfare standards for cleaner fish used in aquaculture
Reduce farmed salmon consumption to lower demand driving intensive lice management
Support closed containment aquaculture that eliminates sea lice exposure