Farmed Salmon Lice Biological Control Welfare

Biological sea lice control using cleaner fish reduces chemical treatment burden but raises welfare questions for the cleaner fish used.

Key Facts

Lumpfish and wrasse are the two main cleaner fish species deployed in salmon farms
Lumpfish are increasingly preferred as they are more effective in winter at colder temperatures
Approximately 40 million cleaner fish are deployed annually across Norwegian and Scottish salmon farming
Cleaner fish suffer high mortality rates from disease, aggression, and inadequate husbandry
Shelter provision significantly improves cleaner fish survival by reducing aggression from salmon
The welfare cost of cleaner fish use must be weighed against reduced chemical treatment burden on salmon

Welfare Considerations

Biological lice control shifts the welfare burden from salmon (reduced chemical exposure) to cleaner fish (direct housing and mortality costs). The net welfare calculation depends on the number of cleaner fish required, their survival rates, and the welfare conditions they experience. Improving cleaner fish husbandry is essential for this biological control method to be welfare-positive overall.

What You Can Do

Support cleaner fish welfare research at Norwegian and Scottish marine science institutions
Choose salmon certified under standards that explicitly include cleaner fish welfare requirements
Ask producers about cleaner fish survival rates and shelter provision in their systems
Advocate for mandatory reporting of cleaner fish mortality rates in aquaculture welfare statistics