Halibut smolt production in hatcheries faces significant welfare challenges from high early mortality, skeletal malformations, and malpigmentation requiring improved management approaches.
Halibut smolt welfare is characterised by extremely high early mortality rates that indicate significant welfare problems in current hatchery systems. The small fraction of larvae surviving to juvenile stage may experience better welfare outcomes, but the losses represent enormous numbers of individuals in poor conditions before death. Skeletal malformations in survivors cause chronic welfare problems persisting through the production cycle. Malpigmentation while not directly painful may indicate developmental welfare compromise. Substrate provision appropriate for benthic species is an important welfare element often neglected in systems designed for pelagic species. Research into halibut larval rearing improvements is needed both for welfare and for making halibut aquaculture economically viable.