Sea lice are the most significant health challenge in Atlantic salmon farming, and treatments to control them carry their own welfare costs. Understanding this trade-off guides better management decisions.
Sea lice management creates a welfare dilemma: untreated heavy infestations cause serious suffering through open wounds, haemorrhaging and immunosuppression, while many treatment methods also impose acute welfare costs. Thermolicer treatments at incorrect temperatures or with excessive crowding can cause significant mortality and internal haemorrhaging. Mechanical treatments damage scales and skin, increasing susceptibility to secondary infections. Wrasse cleaner fish used as biological control have their own welfare needs that are frequently unmet in cage culture. Each treatment decision involves weighing the welfare cost of treatment against the welfare cost of continued infestation, requiring farm-specific decision frameworks.