Sea lice infestations cause significant welfare harm to farmed Atlantic salmon, and the industry is increasingly adopting integrated pest management approaches to reduce chemical treatments.
Sea lice represent both a welfare problem and a biosecurity challenge in salmon farming. The lesions they cause range from surface irritation to deep tissue damage exposing the skull in severe infestations, representing significant ongoing pain. Chemical treatments, while effective, impose their own welfare costs through handling stress and the toxic effects of the chemicals themselves. Integrated pest management approaches — combining biological control, behavioral manipulation, physical barriers, and precision mechanical removal — aim to reduce overall lice burden while minimizing chemical welfare costs. The welfare calculus of these approaches is complex, requiring evaluation of both lice-related harm and treatment-related harm. Facilities that successfully reduce lice levels through non-chemical means achieve better outcomes for fish welfare and wild fish conservation simultaneously.