Atlantic Halibut

All flatfish, including the Atlantic halibut, hatch looking like an entirely ordinary, upright, symmetrical fish with one eye on each side of the head, swimming and behaving much like other young fish. As the larva develops, however, it undergoes a remarkable transformation in which the skull bones on one side gradually reshape and one eye physically migrates up and over the top of the head to sit alongside the other eye, at which point the young fish tips onto its side and begins its life as a bottom-dwelling flatfish, permanently lying with both eyes facing upward toward the light.

Among the roughly 800 species classified as flatfish, none grows anywhere near as large as the Atlantic halibut, which can reach lengths of 2 to 3 metres and weights recorded well over 300 kilograms in historic catches, dwarfing other well-known flatfish such as sole, plaice, or even the Pacific halibut, its closest large relative. This exceptional size likely reflects its position as an active, wide-ranging predator of other fish rather than a smaller, more sedentary invertebrate-feeder, combined with a long lifespan and slow, steady growth that allows individuals to keep adding size for decades.

Its large size, high market value, and slow reproductive rate made it an extremely attractive commercial target from the earliest days of North Atlantic fisheries, and heavy, largely unmanaged fishing throughout the 19th and 20th centuries removed adult fish faster than the slow-maturing population could replace them, particularly since females may take a decade or more to reach breeding age. By the time serious conservation measures were introduced, wild stocks in many areas had already collapsed to a small fraction of historic levels, and despite catch limits and other management efforts, recovery has been slow, which is why most Atlantic halibut sold commercially today comes from aquaculture rather than wild fisheries.

Yes, farmed Atlantic halibut is genetically the same species as its wild counterpart, raised in aquaculture facilities specifically because wild populations have been depleted to the point where a large-scale wild fishery is no longer considered sustainable in most regions. Halibut aquaculture developed relatively recently compared to salmon farming, since halibut have a more complex life cycle and specific rearing requirements, but it has grown steadily and now supplies most of the Atlantic halibut reaching restaurants and shops, allowing continued consumer access to the fish while reducing direct pressure on the remaining wild stock.