Sea Lice Prevention and Salmon Welfare

Preventing sea lice infestation is preferable to treating established infestations, with welfare benefits for both salmon and the cleaner fish used for biological control.

Key Facts

Coordinated area management reduces the transmission of sea lice between farms
Freshwater treatments kill sea lice without harming salmon by exploiting osmotic differences
Deep light systems alter salmon distribution to avoid lice-bearing surface waters
Snorkel designs prevent salmon accessing surface water where Lepeophtheirus larvae concentrate
Selective breeding for lice resistance is an emerging long-term prevention strategy

Welfare Considerations

Sea lice prevention avoids both the welfare harm of infestation and the welfare costs of treatment. Coordinated area management that synchronizes fallow periods between neighboring farms breaks the lice transmission cycle and reduces overall infestation pressure. Technological prevention methods including deep lights, snorkels, and submerged feeding systems reduce louse attachment without the handling stress of treatments. Selective breeding programs are developing lines with enhanced immune resistance to lice. Prevention is consistently more welfare-positive than treatment because it avoids both the welfare harm of lice and the stress of handling during treatment procedures. The economics of prevention versus treatment also favor prevention in most scenarios.

What You Can Do

Support salmon producers investing in technological lice prevention systems
Advocate for coordinated area management as a regulatory requirement in salmon farming regions
Choose salmon from farms with documented low lice burden through prevention-first approaches
Back selective breeding research for louse-resistant salmon as a long-term welfare and sustainability solution