Farmed Salmon Welfare and Sea Lice

Sea lice infestations in salmon aquaculture cause chronic pain and tissue damage to millions of farmed fish, representing one of the largest fish welfare problems in existence.

Key Facts

Sea lice consume the mucus, skin, and blood of salmon causing open wounds and secondary infections
A single sea louse infestation can kill a salmon smolt within weeks
Norwegian salmon farms lost an estimated 18 million fish to lice-related mortality in a single year
Chemical treatments for sea lice including hydrogen peroxide baths cause additional acute stress
Cleaner fish species like wrasse and lumpfish are used to eat lice but face their own welfare challenges

Welfare Considerations

Sea lice cause chronic pain through tissue erosion that can expose underlying musculature. Infested fish show reduced feeding, increased cortisol, and impaired immune function. The treatment of infested fish — bathing in warm or chemically treated water — adds acute thermal or chemical stress on top of chronic lice-related suffering. Cleaner fish used to control lice are often raised in conditions far below their behavioral needs and experience high mortality. Sea lice represent a major unsolved welfare challenge requiring investment in closed containment and biological control research.

What You Can Do

Support higher-welfare salmon certification that includes sea lice monitoring standards
Reduce farmed salmon consumption or choose land-based recirculating aquaculture system salmon
Advocate for regulatory limits on acceptable sea lice infestation levels on farms
Support research into non-chemical, low-stress sea lice control methods