Sea lice infestations in farmed salmon cause significant welfare harm, and treatment methods carry their own welfare costs, requiring integrated approaches that minimize total suffering.
Sea lice management involves choosing between the welfare harm of infestation and the welfare harm of treatment. Both untreated lice damage and aggressive treatment cause suffering; the welfare-optimal approach prevents infestation to minimize both. Preventive strategies including deep lights that keep salmon below lice-infested surface waters, snorkel barriers, and cleaner fish deployment reduce infestation rates and treatment frequency. When treatment is necessary, welfare-conscious farms select methods with the best efficacy-to-stress ratio and monitor fish carefully during and after procedures.