down to . It has a circumpolar distribution in the Northern Hemisphere and is found in both the North Atlantic and the North Pacific Oceans. In the North Pacific, it ranges from the Sea of Japan near Honshu northwards to the Chukchi Sea, east through the Aleutian Islands, and south as far as northern Baja California in Mexico. In the North Atlantic, it occurs from the British Isles to northern Norway, Faroe Islands, Iceland, and eastern Greenland in the east and from Newfoundland to northwestern Greenland in the west. Biology As a species of flatfish, it is presumed that this fish would be primarily associated with the seabed, however, tagging information shows that they spend time both close to the seabed and with frequent excursions into the water column, presumably for feeding. These movements up into the water column explain why it is often caught pelagically. It has been speculated that when in the water column they will swim in a vertical position, but data from data storage tags do not support this hypothesis. Greenland halibut consumes prey from demersal and pelagic habitats and is primarily a piscivore. It also feeds upon a variety of other prey items such as amphipods and shrimps. In the north-east Arctic, squid and fish such as Atlantic herring, capelin and Atlantic cod are important components of their diet, with squid making up a greater component of the diet of smaller individuals. In the Beaufort Sea, polar cod and Gelatinous Snailfish are important prey items while in the shrimp grounds of west Greenland, shrimp and redfish are the primary prey. They are known to feed on significant quantities of offal discarded from fishing vessels. Greenland halibut spawn from January–March. During spawning, Greenland halibut will perform spawning rises where they will rise up through the water column from deep water to depths of around 200–350 m where they will release their eggs and sperm before descending back to deeper water. Females will release one batch of eggs each year after while the males will spawn with multiple females over the course of the spawning season. The eggs and larvae remain suspended in the water column throughout development and complete their metamorphosis on attaining a length of Greenland halibut have an unusual form of gonad development in comparison with many other fish species. They will develop two groups of oocytes concurrently, one group will be spawned in