| ||Gadus callarius Linnaeus, 1758|
| ||Gadus vertagus Walbaum, 1791|
| ||Gadus heteroglossus Walbaum, 1792|
| ||Gadus ruber Lacepède, 1803|
| ||Morhua vulgaris Fleming, 1828|
| ||Gadus arenosus Mitchill, 1815|
| ||Gadus rupestris Mitchill, 1815|
| ||Morhua punctata Fleming, 1828|
| ||Gadus nanus Faber, 1829|
| ||Morrhua americana Storer, 1858|
| ||Gadus callarias kildinensis Derjugin, 1920|
| ||Gadus morhua kildinensis Berg, 1933|
| ||Gadus morhua morhua Svetovidov, 1948. The species name morhua is incorrectly spelled as morrhua by many authors|
|En - Atlantic cod, Fr - Morue de l'Atlantique, Sp - Bacalao del Atlántico.|
3Alpha Code: COD Taxonomic Code: 1480400202|
|Scientific Name with Original Description|
|Gadus morhua Linnaeus, 1758, Svst.Nat., ed. X:252.|
|Head relatively narrow, interorbital space 15 to 22% of head length. Predorsal distance less than about 33% of length;
Colour: variable, brownish to greenish or grey dorsally and on upper side, pale ventrally.|
|Cape Hatteras to Ungava Bay along the North American coast; east and west coasts of Greenland extending for variable distances to the north, depending upon climate trends; around Iceland; coasts of Europe from the Bay of Biscay to the Barents Sea, including the region around Bear Island.|
|Habitat and Biology|
|The Atlantic cod is generally considered a demersal fish, although its habitat may become pelagic under certain hydrography conditions, when feeding or spawning. The presence of cod usually depends on prey distribution rather than on temperature.However, whatever the reason, larger fish are found in colder waters in most areas (0-5°C). It lives in almost every salinity from nearly fresh to full oceanic water, and in a wide range of temperatures from nearly freezing to 20C°.|
This species is widely distributed in a variety of habitats from the shoreline to well down the continental shelf, to depths over 600 m, but is mostly found within the continental shelf areas from 150-200 m.Tagged cod at Jan Mayen, which have been recaptured on the spawning grounds around Iceland, indicate that these fish must have crossed in water over 1000 m deep. It is unlikely that cod swim as deep as this; although, they have been trawled in depths up to 460 m.While Atlantic cod is essentially a fish of the open sea, it appears regularly in various river mouths in Maine and Massachusetts during late autumn and winter. Cod are gregarious during the day; forming compact schools that swim between 30 and 80 m above the bottom, and scatter at night. To the south of its range, cod is found in shallow water only during the winter and there, as elsewhere, it is the younger smaller fish that live close inshore.
Although some groups of small cod are relatively stationary, individuals or groups may perform astonishingly long migrations. Some individuals migrate from native waters never to return, and movements of migrating individuals may be of the order of 5 km per day. A speed as high as 25.7 km/day for nearly a month has been calculated for a fish moving from east to west Greenland. Greenland cods have been observed to perform migrations over 1000 km, northeastern Atlantic cod, 800-900 km, while cod of the North Sea, the Channel, and the Irish Sea undertake migrations of lesser magnitude.In the Baltic, there is a tendency to migrate toward the Bornholm Basin (spawning and feeding ground). Arcto-Norwegian cod spends most of the year in the Barents Sea, but migrates seasonally to the Norwegian coast for spawning. In the western Atlantic, Gulf of Maine, cod may be driven out of the southernmost part of its range in summer and early autumn by increased water temperatures to waters of the polar current along the eastern coast of Labrador, which they leave again later in autumn to pass winter and spring either more southward or in deep waters.
Very little is known about the movements of young cod in their early years on the nursery grounds .There is a possibility that they undertake a seasonal migration to shallow water during the summer and return to deeper water in winter, although there is no evidence to support this. Movements seem to be restricted to feeding. The 3 and 4 year old immature cod move about in the Barents Sea when they follow the spawning capelin to the coast in March and April, and in the summer, they leave the coastal area and disperse, feeding on capelin and herring over the Barents Sea When they are older, the young cod join the mature fish and make their first full spawning migration.
The earliest reported maturities for the Atlantic cod are at 2 years in its eastern (Oslofjord) and at 4 years in its western distribution.
Although this fish has separate sexes, hermaphrodite specimens have been reported. The sex ratio is nearly 1:1, with a slight predominance of females. This is one of the world's most fecund fishes, with an average production of 1 million eggs per female. A 5 kg female produces approximately 2.5 million eggs; a 10 kg female 5 million and a 15 kg female, 7.5 million. The maximum production recorded is 9 millions eggs of a 34 kg fish. The eggs and the larvae up to 2.5 months are pelagic; subsequently the postlarvae settle to the bottom.
Although the spawning period varies among the North Atlantic subpopulations, most cod in the eastern and western parts of this ocean spawn from December to June, i.e., Norwegian coast, from February to April; Baltic Sea, April to July; North Sea, December to May; Gulf of Maine, November to April; Newfoundland, April to June; West Greenland, March to June; and southwestern Gulf of St. Lawrence, May to September. Usually the cod spawn at or near the bottom. There is some evidence that cod leave the bottom and school pelagically to spawn in preferred temperatures when bottom temperatures are unsuitable.
The maximum range of temperature for spawning is from below 0°C to about 1 2°C, with most spawning taking place over the lower half of this range. The Gulf of Maine stock spawns in colder waters than the other stocks. The distribution of spawning stocks widely depends on the oxygen content of the bottom water but on the whole, cod are rather local in their choice of spawning grounds in the Gulf of Maine as well as in Norwegian waters.
The major spawning area in the eastern Atlantic is the North Sea, generally at depths of less than 50 m and never beyond 200 m, especially in the Bornholm basin (Denmark) where the egg density appears to be rather high (late April, end of May). The most productive spawning ground in the western Atlantic is the eastern half of Georges Bank and the area south of the Grand Banks (Newfoundland). The second largest ground is the southwestern part of the Gulf of Maine, between Nantucket Shoals and Bay of Fundy. The Atlantic cod spawns once a year.
The growth rate is rather high, the females growing slightly faster than the males. It also varies from one area to another: for example, it is known that fish from the English Channel and the North Sea grow faster than those living at higher latitudes. Three-year-old fish average 56 cm (males) and 59 cm (females); 5-year olds, 81 cm (males) and 85 cm (females). The species lives up to 20 years.
The Atlantic cod is a voracious and omnivorous species. Larvae and postlarvae feed on plankton, juveniles mainly on invertebrates, and older fish on invertebrates and fish, including young cod. Small crustaceans are of oustanding importance (90%) in the food of juveniles (up to 25 cm length). They are progressively replaced by decapods of medium and large size. Fish become more important than crustaceans in the diet of older individuals. Other systematic groups play a smaller role as forage organisms: polychaetes (less than 10%); echinoderms and other benthic organisms (minor quantities); and occasionally seaweeds (Irish moss - Chondrus crispus) and others. While the proportion of benthic organisms shows hardly any change throughout the year, fish consumption varies seasonally. Deep-water cod show preference for herring throughout the summer and autumn (peak June-July), but in winter and during the spawning period, they sustain themselves on mixed food in coastal areas. Feeding occurs at dawn and dusk, but small fish (of less than 20 cm) feed continuously.
|The various races reach different sizes, the oceanic cod often reaches 1 m and is known to attain a length of 2 m. Local races have smaller fish.|
|Interest to Fisheries|
|Among the most important of all commercial fishes, cod has been called "beef of the sea". The Atlantic cod has been exploited ever since man began to fish in the seas of Europe. Its value as a prime food-fish is enormous, and when salted and dried, it keeps for winter-time use or export.|
In 1995, catches of 31,326 t have been reported to FAO for area 21 (dropped from 639,936 t in 1989) and of 1,232,779 t in area 27.
The Atlantic cod is caught mainly with bottom otter trawls and pelagic trawls. Devices such as handlines and cod traps are being recently replaced by gillnets (especially in Newfoundland). Other types of gear used are longlines, Danish seines, purse seines, twin beam trawls, light trawls, shrimp trawls and pound nets. The Atlantic cod is fished throughout the year in the Gulf of Maine, large catches are made on rock and pebble grounds but also on soft bottoms. The major fishing grounds are boreo-arctic, mostly around Iceland, in the Barents Sea, off Newfoundland and West Greenland, in the Norwegian Sea, off Spitzbergen, and around Bear Island. The total catch reported for this species to FAO for 1999 was 1 092 859 t. The countries with the largest catches were Iceland (260 6431 t) and Norway (256 637 t).
It is marketed fresh, chilled or frozen as fillets or whole, salted or sugar-salted, dried and salted, dried and unsalted, in brine, or smoked. Other products obtained from cod are salted cheeks, liver oil and eggs (smoked or as frozen roes).
|G. morhua includes a number of races that are characterized by size, colour, swimbladder morphology, temperature and/or salinity preferences, migratory behaviour and geographical distribution. Taxonomically named populations include G. morhua callarias, a low salinity, non-migratory race restricted to parts of the Baltic, G. morhua kildinensis, restricted to a small lake on an island near the entrance to Kola Bay, and G. morhua morhua natio hiemalis, a race that migrates in and out Kandalaksha Bay.|
Bigelow & Schroeder, 1953
Harden Jones, 1968
Wise, 1961, 1963