Atlantic halibut aquaculture faces unique welfare challenges from its unusually long production cycle, aggressive juvenile behaviour, and the physiological transitions of flatfish development.
The extended production cycle of farmed halibut means individual fish may spend several years in culture conditions, making chronic welfare state more significant than in short-cycle species. The metamorphic transition from symmetrical to flatfish body plan is physiologically demanding. Cannibalism in juvenile tanks causes injury and death that management can reduce but not eliminate. The species' preference for lying on the bottom means appropriate substrate provision is a welfare consideration not relevant to pelagic species. Investment in welfare standards before the industry scales significantly would prevent the welfare problems that have characterised salmon aquaculture.