Sea lice are the most significant welfare and economic challenge in Atlantic salmon aquaculture, with treatment methods that must balance lice control against their own welfare costs.
Sea lice management in salmon aquaculture creates a genuine welfare dilemma: untreated lice cause progressive, painful skin damage and systemic stress, but treatments also cause acute welfare harms. The challenge is finding the optimal approach that minimizes cumulative welfare harm across both the lice burden and the treatment response. Laser systems that target lice individually show promise as the least aversive option. Cleaner fish welfare is an overlooked component — the wrasse and lumpfish used for biological control experience very high mortality in sea pens and are rarely provided with welfare consideration despite being vertebrates with nociception. A holistic welfare approach accounts for all species in the pen system, not only the salmon.