Sea lice are a major health challenge for farmed Atlantic salmon, and the treatments used to control them cause significant welfare harm to fish.
Delousing procedures involve handling, crowding and exposure to physical or chemical stressors that cause measurable physiological stress and mortality. Thermal delousing at high temperatures causes heat shock. Mechanical methods cause physical trauma. Chemical treatments require precision dosing to avoid toxicity. Sea lice management is the single largest welfare challenge in salmon aquaculture, and reducing treatment frequency through genetic resistance or cleaner fish is a priority.