Salmon Lice and Welfare in Aquaculture

Sea lice are parasitic crustaceans that cause significant suffering for farmed Atlantic salmon and threaten wild fish.

Key Facts

Sea lice (Lepeophtheirus salmonis) are the primary pest in salmon farming
Heavy infestations cause open wounds, scale loss, and secondary infections
Chemical treatments have driven resistance in louse populations worldwide
Non-chemical methods include cleaner fish, freshwater baths, and laser systems
Wild salmon populations near farms show elevated louse loads that reduce survival

Welfare Considerations

Sea lice infestation causes demonstrable suffering in salmon. Affected fish show abnormal behaviors including jumping, rubbing against nets, and reduced feeding. Open lesions from lice feeding allow bacteria and fungi to invade, causing systemic infection. Some chemical treatments also stress fish and can harm non-target species. Cleaner fish used to eat lice — particularly wrasse and lumpfish — face their own welfare problems in farms, where they often die prematurely of disease. Integrated pest management is essential for both fish welfare and wild population protection.

What You Can Do

Choose salmon certified by standards with louse count monitoring requirements
Support research into non-chemical louse control technologies
Advocate for farm siting regulations that protect wild salmon migration routes
Learn about closed-containment aquaculture as a louse-free alternative
Support funding for welfare-centered aquaculture research