Aquaculture

Farmed Salmon and Sea Lice: A Persistent Welfare Crisis

Sea lice infestations on farmed Atlantic salmon are one of the most significant welfare problems in aquaculture globally, causing tissue damage, immunosuppression, and substantial mortality.

Key Facts

Sea lice (Lepeophtheirus salmonis) feed on salmon skin and mucus, causing lesions
Heavy infestations cause open wounds, secondary infections, and death
Lice also spread from farms to wild salmon, threatening migratory populations
Chemical treatments (azamethiphos, hydrogen peroxide) have welfare costs themselves
Mechanical treatments (warm water, laser systems) are increasingly used but cause acute stress

Welfare Considerations

Sea lice cause chronic pain through progressive tissue damage. Heavy infestations compromise osmoregulation. Treatment by warm water (Thermolicer) causes acute thermal shock and fin damage. Laser treatments cause startle responses and avoidance behavior. The welfare cost of sea lice management is high regardless of which treatment is used.

What You Can Do

Choose land-based aquaculture salmon when available — free of sea lice risk
Advocate for tighter sea lice threshold standards in national aquaculture regulations
Support research into cleaner fish (wrasse, lumpfish) used as biological lice control
Reduce farmed Atlantic salmon consumption given ongoing welfare challenges