Sea lice infestations are the most significant health and welfare challenge in farmed salmon. The treatments themselves raise welfare concerns, making integrated lice management a complex welfare balancing act.
Sea lice represent one of the most significant ongoing welfare challenges in salmon aquaculture. The lice themselves cause painful lesions and physiological stress. But many of the treatments also cause welfare harm: thermolicer systems heat water to 34C to kill lice, causing thermal shock and mortality in treated fish; hydrolicer systems use high-pressure water jets that also cause significant stress and injury. Biological control using wrasse cleaner fish improves welfare over chemical and mechanical treatments but requires managing wrasse welfare alongside salmon. Selective breeding for lice resistance, closed containment systems, and precision aquaculture monitoring represent the longer-term path to reducing lice pressure while minimizing treatment welfare costs.