Atlantic halibut  (Hippoglossus hippoglossus)

The Atlantic halibut has a relatively slow growth rate and late onset of sexual maturity (5), with males attaining maturity at seven to eight years old, females at ten to eleven years (4), and individuals are thought to live up to a 50 years (3). Little is known about their breeding except that spawning is seasonal, although its timing varies somewhat with location. In the Eastern Atlantic spawning occurs chiefly in March, April and May, although may span from January to June. Off the American coast, however, the spawning season appears to continue through the summer as late as September (3). After spawning both sexes migrate northwards in search of food (4). Young individuals feed on crustaceans like crabs and prawns, but older fish feed more on other fish, such as cod, haddock, herring and skate (4) (5). These halibut lie motionless and invisible on the sea bed, capturing any fish that pass within reach (3), although they may also hunt for fish in open water (4).