Sea lice treatment in farmed salmon involves procedures ranging from chemical baths to mechanical removal, each with specific welfare implications for the treated fish.
Sea lice treatment welfare presents a genuine dilemma: untreated sea lice infestations cause significant and escalating welfare harm, while treatment methods themselves impose acute welfare costs through chemical, thermal, or mechanical stress. This is not a binary welfare choice but a comparative one — the welfare profile of each treatment option must be weighed against the harm of continued infestation. Biological control through cleaner fish offers the most continuous and behaviorally integrated approach, though cleaner fish welfare itself requires attention. Long-term welfare improvements depend on structural changes: sea lice-resistant genetics, enclosed systems that prevent infestation, and breeding selection for resistance are the most durable solutions that reduce both lice burden and treatment-related welfare harm.