. However, haddock are rarely over in length and the vast majority of haddocks caught in the United Kingdom measure between . In eastern Canada waters, haddock range in size from in length and in weight. Distribution The haddock has populations on either side of the north Atlantic but it is more abundant in the eastern Atlantic than it is on the North American side. In the north-east Atlantic it occurs from the Bay of Biscay north to Spitzbergen; however, it is most abundant north of the English Channel. It also occurs around Novaya Zemlya and the Barents Sea in the Arctic. The largest stocks are in the North Sea, off the Faroe Islands, off Iceland and the coast of Norway but these are discrete populations with little interchange between them. Off North America, the haddock is found from western Greenland south to Cape Hatteras, but the main commercially fished stock occurs from Cape Cod and the Grand Banks. Habitat and biology The haddock is a demersal species which occurs at depths from , although it is most frequently recorded at . It is found over substrates made up of rock, sand, gravel or shells and it prefers temperatures of between . Off Iceland and in the Barents Sea, haddock undergo extensive migrations, but in the north western Atlantic its movements are more restricted, consisting of movements to and from their spawning areas. They reach sexual maturity at 4 years old in males and 5 years old in females, except for the population in the North Sea which matures at ages of 2 years in males and 3 years in females. The overall sex ratio is roughly 1:1, but in shallower areas, females predominate, while the males show a preference for waters further offshore. The fecundity of the females varies with size: a fish of length bears 55,000 eggs while a fish at has 1,841,000 eggs. Spawning takes place from depths of around . In the northwestern Atlantic spawning lasts from January to July, although it does not occur simultaneously in all areas, and in the northeastern Atlantic the spawning season runs from February to June, peaking in March and April. The eggs are pelagic with a diameter of , and they take one to three weeks to hatch. Following metamorphosis, the past larval fish remain pelagic until they attain a length of around , when they settle to a