Sea lice control in farmed Atlantic salmon involves mechanical, thermal and chemical treatments, each carrying significant welfare costs that must be weighed against the disease burden of infestation.
Delousing is an inescapable reality of open-pen sea farming - without treatment, sea lice cause severe welfare problems and economic losses. But the treatments themselves cause significant acute suffering. Welfare improvement requires minimising treatment frequency through preventative measures (cleaner fish, snorkels, skirts, fallowing), using the least harmful effective treatment, optimising water temperature and fish condition before treatment, and providing recovery time after procedures. Some welfare advocates argue that only closed-containment systems can adequately protect salmon welfare from this dilemma.