Sea lice infestations are a major welfare and production challenge in farmed Atlantic salmon, causing tissue damage and stress that compromise fish welfare significantly.
Sea lice cause genuine suffering in farmed salmon through tissue damage and secondary infection from feeding wounds. Fish with heavy infestations show abnormal behaviors including jumping, rubbing against surfaces, and reduced feeding - behavioral indicators of distress and pain. Chronic lice pressure impairs immune function, making fish vulnerable to secondary pathogens. Treatment methods have their own welfare implications: chemical bath treatments cause acute stress, while cleaner fish like wrasse experience significant mortality and welfare problems. Physical removal methods including laser and pressurized water systems cause acute stress during treatment. Reducing lice pressure through integrated pest management and closed containment systems benefits both fish welfare and wild salmon conservation.