Wrasse Welfare: Cleaner Fish in Salmon Farming

Wrasse used as cleaner fish in salmon farming are crucial for sea lice control but face severe welfare challenges in farm environments far removed from their natural habitat.

Key Facts

Over 50 million wrasse are deployed on Scottish salmon farms annually as biological sea lice control
Wild-caught and hatchery-reared wrasse are both used, with significant welfare differences
Wrasse naturally live in complex rocky reef habitats and are highly territorial
Wrasse mortality in salmon sea cages regularly exceeds 50% annually due to stress and disease
Wrasse require shelter structures in sea pens as they naturally hide at night and during disturbance

Welfare Considerations

Wrasse deployed in salmon sea cages experience severe welfare compromise from conditions that are fundamentally unsuitable for these reef-dwelling fish. They cannot escape predatory salmon behaviour, lack adequate shelter, and are exposed to cold water temperatures that impair their immune function. Wild-caught wrasse experience additional capture and transport stress before deployment. High mortality rates indicate chronic welfare failure. Yet without effective alternatives, wrasse are integral to sea lice control strategies that protect salmon welfare. The tension between wrasse welfare and salmon welfare highlights the complex trade-offs within aquaculture system design.

What You Can Do

Advocate for mandatory minimum welfare standards for wrasse in salmon farming
Support research into alternatives to wrasse that reduce reliance on cleaner fish
Ask salmon producers about wrasse mortality rates and welfare management practices
Support certification schemes that include cleaner fish welfare in audit standards
Learn about the ecological consequences of large-scale wild wrasse removal from reef systems