Halibut have elongated bodies, a large mouth, and flanks that vary in colour from dark brown to greenish grey, pale grey or white. The fish is easily recognisable as its two eyes are on the same side of its head. It mainly feeds on other fish and large crustaceans, while it is itself the prey of cod, salmon and seals. Between February and May, females lay eggs in deep waters, at depths of between 700 and 1000 metres, releasing up to 4 million eggs each.
The halibut fishing season runs from March to November, primarily in Greenland, Alaska, Canada, Norway and Japan. In the North Pacific, the only authorised fishing method is trolling or longline fishing. This consists of trailing a main line to which side lines with floats and hooks are attached. Fishermen raise the hooks one by one, retrieve the halibut and release any other fish.
Norway has developed white Atlantic halibut farming, since it is difficult to catch. Although wild white halibut can reach 100 kg, farmed fish are sold at the age of 3 to 4 years, before they reach maturity, when they weigh between 1 and 7 kg.