Sea lice infestations are among the most significant welfare problems in farmed Atlantic salmon, causing chronic skin lesions and requiring repeated stressful treatments.
Sea lice represent a chronic welfare burden for farmed salmon from which there is no relief without human intervention. Heavy infestations cause persistent pain from open wounds, altered swimming behaviour, and immune suppression. The treatment cycle creates additional welfare insults: chemical bath treatments cause acute respiratory stress, while mechanical removal using hydrolicer equipment causes physical trauma. Cleaner fish used as biological control agents themselves face significant welfare challenges including high mortality from disease and handling. The fundamental welfare solution is containment systems that prevent lice access - closed-containment and land-based aquaculture eliminate this welfare problem entirely.