Sea lice infestations are the most significant ongoing welfare challenge in salmon aquaculture. Treatment methods themselves carry welfare costs that must be weighed against the harm of infestation.
Sea lice management in salmon farming involves difficult welfare tradeoffs. Untreated lice cause chronic pain through skin damage and immune stress. However, many treatment methods cause acute distress: thermal delicing causes scale loss and stress responses, mechanical removal injures fish, and chemical treatments compromise water quality. The welfare equation must weigh chronic infestation harm against acute treatment harm. Cleaner fish species like wrasse and lumpfish deployed to eat lice have their own welfare needs that are frequently unmet. Enclosed recirculating systems that prevent sea lice exposure from wild fish represent the most fundamental solution, though capital costs are high. Continued research into welfare-sparing lice management is a priority.