Fish Net Pen Welfare and Sea Lice

Sea lice infestation is one of the most significant welfare and sustainability problems in net pen salmon farming, causing chronic skin damage and distress in affected fish.

Key Facts

Sea lice are parasitic copepods that naturally occur in marine environments but reach damaging densities around salmon farms
Heavy sea lice infestations cause skin erosion, open wounds, and secondary infections in farmed salmon
Controlling sea lice requires repeated treatments including medicinal baths and mechanical removal processes that are stressful for fish
Mechanical lice removal processes including laser systems and water pressure jets can cause physical injury and significant stress
Sea lice from salmon farms affect wild salmon populations swimming through areas of high farm density
Consumer certification schemes including ASC (Aquaculture Stewardship Council) include sea lice management requirements

Welfare Considerations

Sea lice represent a chronic welfare problem that runs through the entire production cycle of net pen salmon farming. A fish with heavy lice burden is experiencing ongoing skin pain as parasites feed, creating open lesions and secondary bacterial infections. Treatment procedures, while necessary, add additional acute stress events. The welfare implications are twofold: the ongoing burden of lice infestation itself, and the stress of treatment procedures. Progress is being made through closed containment systems that separate fish from wild lice, and through integrated pest management reducing chemical treatment burden. Certification schemes that require monitoring and maximum lice loads create market pressure for improved management.

What You Can Do

Choose ASC-certified salmon where available as this standard includes sea lice management requirements
Reduce overall salmon consumption especially from uncertified intensive net pen operations
Advocate for investment in and transition to closed containment salmon farming systems that eliminate sea lice exposure
Support research into improved sea lice control methods that minimize fish welfare impacts
Ask retailers about sea lice monitoring and control practices in their salmon supply chains
Donate to aquatic animal welfare organizations working on farmed fish welfare standards