cod

Gadus
Gadus morhua, Atlantic cod
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Gadiformes
Family:	Gadidae
Genus:	Gadus
Species
Gadus morhua Gadus macrocephalus Gadus ogac

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Cod is the common name for the genus Gadus, belonging to the family Gadidae, and is also used in the common name for various other fishes. Cod is a popular food with a mild flavor, low fat content and a dense, flaky white flesh. Cod livers are processed to make cod liver oil, an important source of Vitamin A, Vitamin D, Vitamin E and omega-3 fatty acids (EPA and DHA). Larger cod caught during spawning are sometimes called skrei. Young Atlantic cod or haddock prepared in strips for cooking is called scrod.

The Atlantic cod, which can change color at certain water depths, has two distinct color phases: grey-green and reddish brown. Its average weight is 5–12 kilograms (11–26 lb), but specimens weighing up to 100 kilograms (220 lb) have been recorded. Cod feed on molluscs, crabs, starfish, worms, squid, and small fish. Some migrate to warm water in winter to spawn. A large female lays up to five million eggs in midocean, a very small number of which survive.

Pollock, and coalfish are often found on the same grounds as codfish in cool Atlantic waters. Pollock have shovel-shaped tails and pale lateral lines and grow to 1 metre (3.3 ft) and 15 kilograms (33 lb). Some grow to 2 metres (6.6 ft) in length.

Cod meat is moist and flaky when cooked and is white in color. In the United Kingdom, Atlantic cod is one of the most common ingredients in fish and chips, along with haddock and plaice. It is also frequently consumed in Portugal and Spain.

Cod are currently at risk from overfishing in the UK, Canada and most other Atlantic countries.^[1]

Taxonomy

At various times in the past, taxonomists incorrectly included many species in Gadus. The great majority of these are now either classified in other genera, or have been recognized as simply forms of one of three species. Modern taxonomy, therefore, recognizes only three species in this genus:

• Gadus macrocephalus - Pacific cod
• Gadus morhua - Atlantic cod
• Gadus ogac - Greenland cod

All these species have a profusion of common names, most of them including the word "cod". Many common names have been used of more than one species, in different places or at different times.

"Cod" that is not cod

Related species

Cod forms part of the common name of many other fish no longer classified in the genus Gadus. Many are members of the family Gadidae; others are members of three related families within the order Gadiformes whose names include the word "cod": the morid cods, Moridae (100 or so species); the eel cods, Muraenolepididae (4 species); and the Eucla cod, Euclichthyidae (1 species). The tadpole cod family (Ranicipitidae) has now been placed in Gadidae.

Cod postage stamp, Newfoundland

Gadiformes include:

• Arctic cod Arctogadus glacialis
• East Siberian cod Arctogadus borisovi
• Eucla cod Euclichthys polynemus
• Pelagic cod Melanonus gracilis
• Polar cod Boreogadus saida
• Poor cod Trisopterus minutus
• Rock cod Lotella rhacina
• Saffron cod Eleginus gracilis
• Small-headed cod Lepidion microcephalus
• Tadpole cod Guttigadus globosus

Some fish have common names derived from "cod", such as codling, codlet or tomcod. ("Codling" is also used as a name for a young cod.)

Unrelated species

Some fish commonly known as cod are unrelated to Gadus. Part of this name confusion is market-driven. Severely shrunken Atlantic cod stocks have led to the marketing of cod replacements using names of the form "x cod", according to culinary rather than phyletic similarity. The common names for the following species have become well-established; note that all inhabit the Southern Hemisphere.

Perciformes

Fish of the order Perciformes that are commonly called "cod" include:

• Blue cod Parapercis colias
• Eastern freshwater cod Maccullochella ikei
• Mary River cod Maccullochella peelii mariensis
• Murray cod Maccullochella peelii peelii
• Sleepy cod Oxyeleotris lineolatus
• Trout cod Maccullochella macquariensis
• The cod icefish family, Nototheniidae, including:
  • Antarctic cod Dissostichus mawsoni
  • Black cod Paranotothenia microlepidota
  • Maori cod Paranotothenia magellanica

Rock cod, reef cod, and coral cod

Almost all coral cod, reef cod or rock cod are also in order Perciformes. Most are better known as groupers, and belong to the family Serranidae. Others belong to the Nototheniidiae. Two exceptions are the Australasian red rock cod, which belongs to a different order (see below), and the fish known simply as the rock cod and as soft cod in New Zealand, Lotella rhacina, which as noted above actually is related to the true cod (it is a morid cod).

Scorpaeniformes

From the order Scorpaeniformes:

• Ling cod Ophiodon elongatus
• Red rock cod Scorpaena papillosa

Ophidiiformes

The tadpole cod family, Ranicipitidae, and the Eucla cod family, Euclichthyidae, were formerly classified in the order Ophidiiformes, but are now grouped with the Gadiformes.

Marketed as

Some fish that do not have "cod" in their names are sometimes sold as cod. Haddock and whiting belong in the same family, the Gadidae, as cod.

• Haddock Melanogrammus aeglefinus
• Whiting Merlangius merlangus

Identification

Cod have three rounded dorsal and two anal fins. The pelvic fins are small with the first ray extended, and are set under the gill cover (i.e. the throat region), in front of the pectoral fins. The upper jaw extends over the lower jaw, which has a well developed chin barbel. The eyes are medium sized, approximately the same as the length of the chin barbel. Cod have a distinct white lateral line running from the gill slit above the pectoral fin, to the base of the caudal or tail fin. The back tends to be a greenish to sandy brown, and showing extensive mottling especially towards the lighter sides and white belly. Dark brown colouration of the back and sides is not uncommon especially for individuals who have resided in rocky inshore regions.

Breeding

Cod divide into several stocks, including the Arcto-Norwegian, North Sea, Faroe, Iceland, East Greenland, West Greenland, Newfoundland, and Labrador stocks. There seems to be little interchange between the stocks, although migrations to their individual breeding grounds may involve distances of 200 miles (320 km)or more.

Spawning occurs between January to April (March and April are the peak months), at a depth of 200 metres (660 ft) in specific spawning grounds at water temperatures of between 4 and 6 °C (39 and 43 °F). Around the UK, the major spawning grounds are in the Middle to Southern North Sea, the start of the Bristol Channel (north of Newquay), the Irish Channel (both east and west of the Isle of Man), around Stornoway, and east of Helmsdale.

Pre-spawning courtship involves fin displays, and male grunting^{[citation needed]}, which leads to pairing. The male inverts himself beneath the female, and the pair swim in circles while spawning. The eggs are planktonic and hatch between 8 to 23 days with larva reaching 4 millimetres (0.16 in) in length. This planktonic phase lasts some ten weeks, enabling the young cod to increase its body weight by 40-fold, and growing to about 2 centimetres (0.79 in). The young cod then move to the seabed and change their diet to small benthic crustaceans, such as isopods and small crabs. They increase in size to 8 centimetres (3.1 in)in the first six months, 14–18 centimetres (5.5–7.1 in) by the end of their first year, and to 25–35 centimetres (9.8–14 in) by the end of the second. Growth tends to be less at higher latitudes. Cod reach maturity at about 50 centimetres (20 in) at about 3 to 4 years of age.

Biome

Cod occupy varied habitat, favouring rough ground, especially inshore. Demersal in depths of between 20–200 feet (6.1–61 m),80 metres (260 ft) on average, although not uncommon to depths of 600 metres (2,000 ft). Off the Norwegian and New England coasts and on the Grand Banks of Newfoundland, cod congregate at certain seasons in water of 30–70 metres (98–230 ft) depth. Cod are gregarious and form schools, although shoaling tends to be a feature of the spawning season.

Predation

Adult cod are active hunters, feeding on sand eels, whiting, haddock, small cod, squid, crabs, lobsters, mussels, worms, mackerel, and molluscs. Young cod avoid larger prey.

Parasites

Cod and related species are plagued by parasites. One of the most interesting is a grotesque and massively modified crustacean, known as the cod worm (Lernaeocera branchialis). This animal starts life as a small free swimming larva that is undoubtedly a crustacean. Its first host is the lumpsucker which it captures with grasping hooks at the front of its body. It penetrates the lumpsucker with a thin filament that it uses to suck blood. Cod worms mate on the lumpsucker and the female takes her fertilized eggs to a cod and clinging to its gills, metamorphoses into something that looks scarcely animal. Her crustacean features give way to a plump, s-shaped, worm-like body. Nestled against the rear of her body is a coiled mass of egg strings. The worm is also grotesque in behaviour because the front part of her body penetrates the body of the fish and enters the rear bulb of the host's heart. Firmly rooted in the cod's circulatory system, the front part of the female parasite grows like the branches of a tree, reaching down into the main artery. The worm extracts nutrients from the cod's blood and remains there, safely tucked beneath the cod's gill cover, eventually releasing her offspring into the water.^[2]

Range

Gadus morhua cod live in the colder waters and deeper sea regions throughout the Northern Atlantic. The Gadus macrocephalus is found in both eastern and western regions of the Pacific.^[3]

Cod Trade/History

Stockfish

Cod has been an important economic commodity in international markets since the Viking period (around 800 AD). Norwegians traveled with dried cod and soon a dried cod market developed in southern Europe. This market has lasted for more than 1000 years, enduring the Black Death, wars and other crises and is still an important Norwegian fish trade.^[4] The Portuguese began been fishing cod in the 15th century. Clipfish is widely enjoyed in Portugal. The Basques played an important role in the cod trade and allegedly found the Canadian fishing banks before Columbus' discovery of America.^[5] The North American east coast developed in part due to the vast cod stocks. Many cities in the New England area located near cod fishing grounds.

Apart from the long history cod differ from most fish because the fishing grounds are far from population centers. The large cod fisheries along the coast of North Norway (and in particular close to the Lofoten islands) have been developed almost uniquely for export, depending on sea transport of stockfish over large distances.^[6] Since the introduction of salt, dried salt cod (clipfish or 'klippfisk' in Norwegian) has also been exported. By the end of the 14th century the Hanseatic League dominated trade operations and sea transport, with Bergen the most important port.^[7]

William Pitt the Elder, criticizing the Treaty of Paris in Parliament, claimed that cod was "British gold"; and that it was folly to restore Newfoundland fishing rights to the French.

In the 17th and 18th centuries, the New World, especially in Massachusetts and Newfoundland, cod became a major commodity, creating trade networks and cross-cultural exchanges. In 1733, Britain tried to gain control over trade between New England and the British Caribbean by imposing the Molasses Act, which they believed would eliminate the trade by making it unprofitable. The cod trade grew instead because the “French were eager to work with the New Englanders in a lucrative contraband arrangement”.^[5] The American settlers traded cod with the French Caribbean for rum-producing molasses. In addition to increasing trade, the New England settlers organized into a “codfish aristocracy”. The colonists rose up against Britain's “tariff on an import”, and inflamed by merchants, including John Hancock and John Rowe, disguised themselves, boarded their own ships and dumped their own goods into the harbor, an event known as the Boston Tea Party (p. 96).^[5]

In the 20th century, Iceland re-emerged as a fishing power and entered the Cod Wars. In the late 20th and early 21st centuries, fishing off the European and American coasts severely depleted stocks and become a major political issue. The necessity of restricting catches to allow stocks to recover upset the fishing industry and politicians reluctant to hurt employment. The 2006 Northwest Atlantic cod quota is 23,000 tons representing half the available stocks, while the Northeast Atlantic quota is 473,000 tons.

Pacific Cod is currently enjoying strong global demand. The 2006 Total Allowable Catch (TAC) for the Gulf of Alaska and Aleutian Islands was 260,000 tons.

Endangered-species controversies in Canada and Europe

Following the early 1990s collapse of Canadian stocks, the Canadian Department of Fisheries and Oceans (DFO) banned Northern cod fishing in 1992, which caused great economic hardship in Newfoundland and Labrador. In 1995, in a controversial move, Brian Tobin the Canadian Federal Minister of Fisheries and Oceans, reopened the hunt on the harp seal, which prey on cod, stating: "There is only one major player still fishing the cod. His name is harp and his second name is seal."^[8]

The DFO partly lifted its ban in 1997, although the International Council for the Exploration of the Sea noted the poor recovery of Canadian stocks.^[9] In general, depleted populations of cod and other gadids appear to recover poorly when fishing pressure is reduced or stopped.^[10]

In 1998, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) listed the Atlantic cod as a species of "special concern", though not as an endangered species. Dr. Kim Bell, who drafted the report for COSEWIC, subsequently stated that the original report in fact had advised endangered status but that pressure by the DFO had suppressed this.^[11]

In 2000, WWF placed cod on the endangered species list. The WWF issued a report stating that global cod catch had suffered a 70 per cent drop over the last 30 years, and that if this trend continued, the world’s cod stocks would disappear in 15 years.^[12] Åsmund Bjordal, director of the Norwegian Institute of Marine Research disputed the WWF's claim, noting the healthy Barents Sea cod population.^[13] Cod is among Norway's most important fishery exports and the Barents Sea is Norway's most important cod fishery.

In 2003, COSEWIC placed the Newfoundland and Labrador fisheries on the endangered species list and Fisheries Minister Robert Thibault announced an indefinite closure in the Gulf of St. Lawrence and off Newfoundland's northeast coast. In a 2004 report, the WWF agreed that the Barents Sea cod fishery appeared to be healthy but that the situation may not last due to illegal fishing, industrial development, and high quotas.^[14]

In 2005 the WWF—Canada accused both foreign and Canadian fishing vessels of deliberate, large-scale violations of the restrictions on the Grand Banks, in the form of bycatch. WWF also claimed poor enforcement by NAFO, an intergovernmental organization with a mandate to provide scientific fishery advice and management in the northwestern Atlantic.^[15][16]

According to Seafood Watch, cod is currently on the list of fish that consumers should avoid. In a book on the subject, Charles Clover claims that cod is only an example of how unsustainable fishing is destroying ocean ecosystems.^[17]

King cod

Periodically a cod with a deformed skull is found; the skull has a distinct top or crown giving it the name "king cod" or kongetorsk in Norwegian. In Norway this rare fish was earlier considered to be able to forecast the weather and was commonly used for that purpose. A woolen thread suspended the fish from the ceiling; its nose would point in a different direction depending on the coming weather. In reality, the thread rather than the fish that caused the movement. The twisted thread served as a primitive hygrometer by reacting to the air's humidity, turning the fish as the humidity rose and fell.

Liver

Cod's soft liver can be tinned and eaten.

See also

References

External links

Wikimedia Commons has media related to: Gadus

Wikispecies has information related to: Gadus

• Codtrace
• fishbase.org - Scientific Names for Gadus
• Fisheries Heritage website, Newfoundland and Labrador
• Long term trends in Norwegian cod fisheries – the pioneers
• Species factsheet on cod from the UK Sea Fish Industry Authority (PDF, 2MB)

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