Sea lice treatments in salmon farming cause significant acute welfare costs through mechanical, thermal and chemical methods, requiring careful welfare assessment alongside their effectiveness in controlling infestation.
Sea lice treatment represents a genuine welfare dilemma in salmon aquaculture: allowing unchecked lice infestations causes chronic suffering; treatment methods cause acute suffering; and doing nothing results in worse outcomes for both individual fish and wild salmon populations that can be infected by farmed fish lice. The welfare-minimizing approach involves treating at lower infestation thresholds before welfare impact becomes severe, choosing methods with the lowest demonstrated welfare cost for the efficacy achieved, minimizing treatment frequency through prevention rather than cure, and investing in breeding programs for lice-resistant salmon strains. Welfare-aware aquaculture certification increasingly assesses sea lice management as a key welfare indicator rather than treating it as purely a production or environmental issue.