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The haddock (''Melanogrammus aeglefinus'') is a salt water fish, found in the North Atlantic Ocean and associated seas. The haddock is easily recognized by a black lateral line running along its white side (not to be confused with pollock which has the reverse, i.e., white line on black side) and a distinctive dark blotch above the pectoral fin, often described as a "thumbprint" or even the "Devil's thumbprint" or "St. Peter's mark".〔(Haddock )〕 Haddock is most commonly found at depths of , but has a range as deep as . It thrives in temperatures of 2 to 10 °C (36 to 50 °F). Juveniles prefer shallower waters and larger adults deeper water. Generally, adult haddock do not engage in long migratory behaviour as do the younger fish, but seasonal movements have been known to occur across all ages. Haddock feed primarily on small invertebrates, although larger members of the species may occasionally consume fish. Haddock range in size between 38 to 69 centimeters in length and 0.9 to 1.8 kilograms in weight.〔(Fisheries and Oceans Canada )〕 Growth rates of haddock have changed significantly over the past 30 to 40 years. Presently, growth is more rapid, with haddock reaching their adult size much earlier than previously noted. However, the degree to which these younger fish contribute to reproductive success of the population is unknown. Growth rates of haddock, however, had slowed in recent years. Some evidence indicates it may be the result of an exceptionally large year class in 2003.〔(NEFSC Ref Doc 02-16 )〕 Spawning occurs between January and June, peaking during late March and early April. The most important spawning grounds are in the waters off middle Norway, near southwest Iceland, and Georges Bank. An average-sized female produces approximately 850,000 eggs, and larger females are capable of producing up to 3 million eggs each year. ==Parasites== Cod and related species are plagued by parasites. For example, the cod worm, ''Lernaeocera branchialis'', starts life as a copepod, a small, free-swimming crustacean larva. The first host used by cod worm is a flatfish or lumpsucker, which they capture with grasping hooks at the front of their bodies. They penetrate the lumpsucker with a thin filament which they use to suck its blood. The nourished cod worms then mate on the lumpsucker.〔Matthews B (1998) (''An Introduction to Parasitology'' ) Page 73–74. Cambridge University Press. ISBN 978-0-521-57691-8.〕 The female worm, with her now fertilized eggs, then finds a cod, or a cod-like fish such as a haddock or whiting. There, the worm clings to the gills while it metamorphoses into a plump, sinusoidal, wormlike body, with a coiled mass of egg strings at the rear. The front part of the worm's body penetrates the body of the cod until it enters the rear bulb of the host's heart. There, firmly rooted in the cod's circulatory system, the front part of the parasite develops like the branches of a tree, reaching into the main artery. In this way, the worm extracts nutrients from the cod's blood, remaining safely tucked beneath the cod's gill cover until it releases a new generation of offspring into the water.〔〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「haddock」の詳細全文を読む スポンサード リンク
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