Sea Lice Management in Salmon Aquaculture

Sea lice infestations cause significant pain and tissue damage to farmed salmon; management approaches vary dramatically in their welfare impact on both salmon and wild fish.

Key Facts

Sea lice are parasitic copepods that feed on salmon skin, mucus, and blood
Heavy infestations cause open wounds, secondary infection, and mortality in farmed salmon
Mechanical treatments (thermal and pressure-based) are effective but cause acute stress during treatment
Chemical treatments (emamectin, azamethiphos) have welfare impacts and environmental risks
Cleaner fish including wrasse and lumpfish are used for biological control but raise their own welfare concerns

Welfare Considerations

Sea lice management is the primary recurring welfare challenge in Atlantic salmon farming. The parasites themselves cause progressive tissue damage and pain if not controlled, while the available control methods carry their own welfare costs. Mechanical treatments cause acute stress. Chemical treatments require assessment of both efficacy and animal and environmental welfare impacts. Cleaner fish used for biological control are often sourced from wild capture or raised in inadequate conditions. An integrated pest management approach that combines site selection, early detection, and the most welfare-protective treatments available represents best current practice.

What You Can Do

Choose salmon from farms that use welfare-assessed integrated sea lice management
Support certification standards that include sea lice threshold limits and treatment welfare assessments
Advocate for welfare standards for cleaner fish used in lice control
Support research on lice-resistant salmon genetics that could reduce treatment needs
Reduce salmon consumption or choose land-based aquaculture systems where lice are not present