How sea lice management in salmon farming affects fish welfare and the development of less harmful treatment approaches.
Sea lice management sits at the center of a complex welfare web in salmon aquaculture. Sea lice infestations cause genuine welfare harm — skin erosion, secondary infections, and physiological stress that compromises immune function. The treatments used to control lice have their own welfare costs: bath treatments require crowding fish and exposing them to chemical stress, while mechanical removal methods involve handling that causes acute stress responses. The welfare calculus requires comparing the ongoing harm of lice against the acute stress of treatment, ideally minimizing both through integrated pest management that prevents high infestation levels. The extension of sea lice welfare impacts beyond the farm to wild salmon populations adds a population-level welfare dimension to individual treatment decisions, making farm siting and management choices a matter of broader welfare significance.