Atlantic halibut aquaculture is a growing sector with specific welfare challenges related to this large, sedentary flatfish including skin darkening, aggression, and slaughter welfare.
Halibut aquaculture welfare reflects the challenges of farming a species with complex ontogenetic needs and a long production cycle. The transformation from pelagic larva to benthic flatfish involves eye migration that, when disrupted by inappropriate light conditions, creates permanently malpositional eyes and associated welfare problems. Skin darkening of the white underside — a stress response — provides a visible welfare indicator in farm populations. The long production cycle means that welfare failures early in life have prolonged consequences, and welfare improvements compound over multiple years of benefit to each individual fish. As this sector expands, developing welfare standards appropriate for halibut biology is important.