Salmon lice infestation causes significant suffering in farmed salmon and threatens wild fish. Treatment methods themselves carry welfare costs requiring careful assessment.
Salmon lice management creates a welfare dilemma: untreated infestations cause chronic suffering, but many current treatment methods also cause acute harm. The industry has expanded treatment frequency to manage increasing resistance, compounding welfare impacts. Each treatment event — whether chemical bath, hyperthermia, crowding or mechanical removal — causes measurable stress and mortality. The systemic solution is reconfiguring production away from open-net pen systems toward closed containment that eliminates lice exposure entirely. Until then, welfare assessment must account for both infestation burden and treatment frequency in any honest evaluation of salmon farm welfare.