Sea lice infestations are a major challenge in Atlantic salmon farming. Treatment methods vary widely in their welfare impacts, creating both production and ethical considerations.
Sea lice treatment represents a central welfare dilemma in salmon aquaculture: allowing lice to proliferate causes welfare harm from wounds and immune stress, but many treatments themselves cause acute welfare problems. Mechanical treatments such as hydrolicer and thermal treatment cause physical injury and thermal shock; chemical bath treatments cause handling stress and may be acutely toxic at high exposures. Cleaner fish, used as biological control, face documented welfare problems including predation, starvation, and injury from salmon. Selective breeding for lice resistance, submerged net pens that reduce surface lice exposure, and improved cleaner fish welfare standards are all being pursued as components of a more welfare-conscious approach to lice management.