The management of sea lice infestations in salmon aquaculture involves treatments that can themselves cause significant fish welfare compromise, requiring careful balancing of infestation and treatment harms.
Sea lice management in salmon farming presents a genuine welfare dilemma: infestation causes significant chronic suffering, but many available treatments cause acute suffering during administration. Thermolicer treatment, which exposes fish to brief high-temperature water to dislodge lice, causes thermal shock responses. Crowding stress during treatment procedures compounds the direct treatment effects. The deployment of cleaner fish, while reducing chemical and mechanical treatment frequency, raises separate welfare concerns about the cleaner fish themselves, which often experience high mortality and inadequate feeding in salmon cages. The ideal welfare solution combines prevention through site management and breeding, early detection through monitoring, and preferential use of the least harmful effective treatment when intervention is required.