Atlantic halibut is one of the highest-value farmed fish in the North Atlantic. Its welfare needs — particularly during early life stages — are poorly understood but significant.
Atlantic halibut welfare during early life stages is particularly challenging. Larvae are highly sensitive to handling, light, and water quality — mortality rates during metamorphosis can be very high, representing significant welfare concern. Metamorphosis abnormalities, including malpigmentation and eye migration failure, indicate developmental welfare problems that persist for the animal's productive lifetime. Malpigmented fish experience social stress from abnormal appearance in competitive feeding environments. Juvenile and adult halibut are relatively tolerant of intensive conditions compared to salmonids, but high stocking densities still cause chronic stress and suppress immune function. Slaughter welfare is a concern — halibut require appropriate stunning methods adapted for a flatfish body plan. The long production cycle means any welfare compromise is experienced for an extended period.