Cod

Cod, common name for fishes of class Actinopterygii, order Gadiformes, family Gadidae. This family contains about 30 species of mostly bottom-living fishes found in cool seas. In Canada, 9 species occur in Atlantic waters, 3 in Pacific and 5 in Arctic. The family includes many important food fishes, eg, haddock (genus Melanogrammus), pollock (Pollachius), Pacific cod (Gadus macrocephalus) and tomcods (Microgadus). Fishes recently removed from the family Gadidae include cusk, burbot, rocklings and lings (now family Lotidae) and hakes (now family Phycidae).

Description

Cods have elongate bodies, large heads with strong mouths and 3 dorsal and 2 anal fins (with the exception of Raniceps raninus of the eastern North Atlantic with single, long dorsal and anal fins). Most species have a single, fleshy barbel (hairlike projection near the tip of the lower jaw). The most important Canadian cod, the Atlantic cod (Gadus morhua), is heavy bodied, with a large head and an almost square caudal (tail) fin. Scales are small and smooth. The lateral line is pale. It may weigh up to 90 kg but usually averages 3-4 kg. Colour varies from grey or silvery green to brown or red, depending on bottom type and locality. The head and body are covered with many brown to reddish spots. Atlantic cod occurs on both sides of the North Atlantic. Off the North American coast, it ranges from Cape Hatteras to southern Baffin Island, but its greatest abundance historically has been off Newfoundland and Labrador. The closely related Pacific cod ranges from central California waters to the Bering Sea.

Reproduction

Spawning usually occurs during cool months, but exact time depends on water temperature and location of spawning grounds. On the Grand Banks (specifically, the Grand Bank proper), spawning occurs Apr-Aug, and on Nantucket Shoals, Oct-Feb. Atlantic cod are prolific: a 100 cm long female may produce about 5 million buoyant eggs. Hatching time depends on water temperature, and may take several weeks. Young cod grow at different rates in different areas: the colder the temperature, the slower the rate of growth. Young cod eat plankton and, as they mature, bottom creatures, but adults are voracious and feed mainly on other fishes (eg, capelin, herring), crustaceans and squids.

Significance of Fishery

Atlantic cod, one of the world's leading food fishes, has been fished on the Grand Banks for centuries. Because of a number of factors, including overfishing and adverse ocean conditions, in 1992 the federal government closed part of the fishery and reduced quotas in other parts within Canada's 200 nautical mile (371 km) zone. Despite closures and strict management the fishery has yet to recover.

See also fisheries.