Sea lice infestations are a major welfare and production problem in Atlantic salmon farming, and treatment methods themselves carry significant welfare costs.
Sea lice control sits at the intersection of animal welfare and aquaculture sustainability. The lice themselves cause significant suffering. But the treatments — chemical, thermal and mechanical — all carry welfare costs including stress, injury and mortality. The welfare of cleaner fish used as biological control is an emerging concern — wrasse and lumpfish have their own welfare needs but receive little attention. Reducing sea lice incidence through site management, fallowing and improved cage design reduces both the welfare harm from infestation and the risks from treatment.