Millions of wild-caught and farmed wrasse are deployed in salmon sea cages to control sea lice. Their welfare as a functional tool species is almost entirely unaddressed, raising serious ethical questions about their use.
Wrasse welfare in salmon farming represents one of the most numerically significant and overlooked welfare issues in aquaculture. Deployed into large, cold, turbulent sea cages populated by thousands of much larger salmon, wrasse experience chronic predation threat, temperature stress, inadequate shelter, and crowding. Mortality rates above 50% indicate profound welfare failure — wrasse die from salmon biting, temperature shock, starvation in winter, and injury from cage infrastructure. Wild capture adds additional welfare concerns through bycatch and acute capture stress. The industry has developed husbandry guidelines for wrasse welfare — including refuge structures, temperature monitoring, and feed provision — but implementation is inconsistent. The use of fish as living biological tools with disposable mortality rates represents an ethically troubling precedent. Welfare scientists have called for minimum welfare standards, mortality monitoring, and alternative sea lice control methods to reduce wrasse dependence.