Wrasse Welfare in Salmon Aquaculture

Wrasse and lumpfish are used as cleaner fish in salmon farming to control sea lice. Their welfare is critically important and often neglected.

Key Facts

Over 50 million cleaner fish are deployed in Norwegian salmon farming annually, primarily wrasse and lumpfish.
Cleaner fish mortality rates in salmon pens are extremely high — often 50-90% per production cycle.
Wrasse are tropical-origin fish deployed in cold Norwegian and Scottish waters outside their thermal comfort range.
Lumpfish reared in hatcheries frequently suffer from deformities, skin conditions, and parasite infestations.
Welfare standards specifically for cleaner fish are only beginning to be developed by industry and regulators.

Welfare Considerations

Cleaner fish welfare represents a significant ethical gap in salmon aquaculture. The welfare logic of replacing chemical sea lice treatment with biological control is sound, but only if cleaner fish welfare is adequately considered. High mortality rates indicate that current deployment conditions are suboptimal — wrasse outside their thermal range experience chronic cold stress that suppresses immunity and reduces effectiveness. Lumpfish reared in suboptimal hatchery conditions arrive in salmon pens already compromised. The welfare of millions of individual cleaner fish must be incorporated into the welfare accounting of salmon production systems. Best-practice cleaner fish programs invest in species-appropriate rearing conditions, appropriate stocking ratios, and hiding places in salmon pens.

What You Can Do

Support salmon certification schemes that include cleaner fish welfare standards.
Advocate for regulatory requirements covering cleaner fish welfare alongside salmon welfare.
Support research into optimal cleaner fish rearing and deployment conditions.
Choose salmon from producers with transparent cleaner fish mortality data and welfare commitments.
Engage with aquaculture welfare organizations to ensure cleaner fish are included in welfare frameworks.