Farmed Salmon Sea Lice Management Welfare

The welfare impact of sea lice infestations and treatment methods on farmed Atlantic salmon.

Key Facts

Sea lice are external parasites causing significant welfare harm and production losses in Atlantic salmon farming
Infestation causes skin lesions, scale loss, and open wounds that impair osmoregulation and immune function
Chemical treatment with hydrogen peroxide and emamectin benzoate are common but have welfare costs during application
Mechanical delousing using hydrolicer and thermolicer devices cause significant physical stress and injury
Biological control using cleaner wrasse has grown substantially but raises wrasse welfare concerns
Closed containment and deep light systems reduce sea lice pressure without chemical treatment

Welfare Considerations

Sea lice management represents one of the most complex welfare challenges in salmon farming because the parasite itself causes welfare harm, while many available treatments also cause acute welfare harm during application. The ideal welfare outcome requires reducing sea lice pressure through prevention rather than reactive treatment — through site selection, fallowing, snorkel barriers, and closed containment. Where treatment is necessary, the least aversive method should be selected. The welfare of wrasse used as biological control must also be considered as their use expands.

What You Can Do

Choose salmon certified under welfare programs that address sea lice prevention and treatment standards
Support investment in closed containment aquaculture systems that eliminate sea lice exposure
Advocate for regulatory standards requiring welfare assessment of delousing treatment methods
Support research into wrasse welfare in biological control programs