Sea lice infestations are one of the most significant welfare challenges in Atlantic salmon aquaculture. Lice cause physical damage, physiological stress, and increased disease susceptibility, while treatments carry their own welfare costs.
Sea lice represent a chronic welfare challenge for farmed salmon that requires ongoing management throughout their sea phase. Heavy infestations cause significant physical damage equivalent to open wounds, causing persistent pain and physiological compromise. Treatments reduce louse burden but the treatments themselves cause handling stress. The welfare calculus requires balancing louse-induced suffering against treatment stress, with the goal of minimising total welfare cost. Non-chemical approaches including cleaner fish and mechanical removal, when effective, reduce the treatment-related welfare burden.