Cleaner Fish Welfare in Salmon Aquaculture: Wrasse and Lumpfish

Cleaner fish used in salmon farming to control sea lice may experience poor welfare in sea cage environments designed for their host species.

Key Facts

Wrasse and lumpfish are deployed in Atlantic salmon cages to eat sea lice
Wrasse mortality rates in salmon cages can exceed 50% annually - a significant welfare concern
Wrasse are tropical and subtropical fish adapted to warmer waters than salmon cages provide
Lumpfish show better tolerance for salmon farming conditions but still face welfare challenges
Provision of refuge structures and appropriate temperature conditions improves cleaner fish welfare
Some salmon farms have improved wrasse welfare through refuge provision and temperature management

Welfare Considerations

Cleaner fish welfare represents a cascading welfare problem: addressing sea lice welfare costs in salmon farming by introducing another fish species that itself experiences poor welfare. Wrasse placed in salmon cages face temperature stress outside their thermal comfort zone, lack of appropriate habitat, and high mortality from stress and predation. Using animals to solve animal welfare problems without addressing the secondary species' welfare perpetuates rather than reduces net welfare harm. The welfare-positive solution addresses sea lice at source through better farming practices rather than deploying additional animals in welfare-compromising conditions.

What You Can Do

Support salmon aquaculture welfare standards that include cleaner fish welfare requirements
Advocate for phasing out cleaner fish use in favor of non-biological sea lice management
Choose salmon from operations that do not use cleaner fish or that have certified cleaner fish welfare programs
Support research into sea lice management approaches that eliminate cleaner fish welfare costs
Engage with aquaculture certification bodies about cleaner fish welfare standards
Reduce farmed salmon consumption to decrease pressure for sea lice management interventions