Halibut and Flatfish Aquaculture Welfare

Atlantic halibut and other flatfish are farmed in growing numbers as a premium seafood product. Their unique biology creates specific welfare challenges that differ significantly from salmonid aquaculture.

Key Facts

Atlantic halibut aquaculture has grown significantly in Norway and Iceland, producing premium fish for European and Asian markets
Flatfish are benthic (bottom-dwelling) animals who rest on the sea floor rather than swimming continuously — their welfare needs differ fundamentally from pelagic species
Juvenile halibut undergo metamorphosis in which one eye migrates to produce the characteristic asymmetric adult form — this developmental stage is welfare-sensitive
Albinism and pseudo-albinism — white skin on the normally dark dorsal surface — affect up to 10% of farmed halibut and is associated with lighting and feeding conditions during early development
Stocking density for flatfish must be assessed as area coverage rather than volume density, as benthic fish compete for bottom space
Pre-slaughter stunning options for halibut are less well-developed than for salmonids and represent an active area of welfare research

Welfare Considerations

Flatfish welfare raises species-specific considerations that highlight the inadequacy of applying salmonid welfare frameworks universally across aquaculture. Halibut's benthic lifestyle means that bottom area per fish, substrate quality, and feeding system design are the critical welfare determinants rather than water volume stocking density. Their metamorphosis is a developmentally sensitive period when environmental conditions significantly affect developmental welfare outcomes including the prevalence of abnormalities. The lack of well-validated pre-slaughter stunning methods for halibut means that slaughter welfare represents an unresolved problem for this species. Investment in species-specific welfare research and welfare standards for flatfish represents an important gap in the current aquaculture welfare landscape.

What You Can Do

Ask retailers about the welfare standards applied to farmed halibut in their supply chains
Support research into pre-slaughter stunning methods for flatfish species including halibut and turbot
Advocate for species-specific welfare standards in aquaculture regulation rather than one-size-fits-all approaches based on salmonid research
Choose halibut products from certified producers who can demonstrate welfare monitoring during farming and humane slaughter protocols