cod
| cod | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Cod ( Gadus morhua ) |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Gadus morhua | ||||||||||||
| Linnaeus , 1758 |
The (Atlantic) cod or cod ( Gadus morhua ) is a marine fish that is found in parts of the North Atlantic and the Arctic Ocean, as well as in the Baltic Sea . Cod used to be found in very large quantities in the North Atlantic. It is one of the most important food fish and is of great importance to the fishing industry. Many stocks are now threatened by overfishing .
Cod and cod are synonyms , but both terms are used differently from region to region: cod is sometimes used as a term for young fish and cod is only used for older fish that are mature for spawning . Fish from the Baltic Sea are called mostly just cod ( Baltic cod ), those from other waters, however cod .
The cod was named Fish of the Year in Germany in 1993 . The general overfishing and in particular the effects of climate change in the event of non-compliance with the 1.5 degree target could endanger the survival of the species.
etymology
In Norway , Denmark and Sweden the cod is called torsk , in Finnish turska , in Poland dorsz and in Russia treska . The sexually mature arctic cod is called skrei in Norway . In English-speaking countries it is called cod , in the Netherlands it is cod , in France it is cabillaud or morue .
The origin of the Dutch name cod - and the resulting German name cod - is controversial. In Kluge , it is assumed that this was "apparently borrowed from Spanish bacalao with a change of consonants (interversion) " (cf. Portuguese bacalhau ). Others suspect an origin from the Basque name bacalaiba , and speculate its origin in turn possibly in early contacts between Basques fishing off Newfoundland and North American indigenous people. Wolfgang Pfeifer rejects Basque origins as "not durable". Even a reverse borrowing of the Spanish and Portuguese names from Dutch is conceivable.
features
The cod has an elongated body that is approximately round in cross-section and reaches a length of one to 1.50 meters and a weight of up to almost 50 kg. The heaviest cod ever documented was caught off the coast of Norway in May 2013, weighed 47 kg and was 1.5 meters long. The maximum body height is one fifth of the body length, the section from the tip of the snout to the beginning of the first dorsal fin is shorter than a third of the body length (longer in the case of the Pacific cod ). Characteristic are the protruding upper jaw and the strong barbels on the lower jaw as well as, as with all cod , the three dorsal fins and the two anal fins. The snout is longer than the diameter of the eyes.
The color of the cod is variable: mottled gray, sandy brown to greenish on the back and sides and light to silvery on the belly. There are also reddish specimens. Reddish and greenish tones are more likely to occur in areas overgrown with algae, while gray tones tend to occur over sandy soils or at greater depths. Specimens living in coastal regions, the cod of the Baltic Sea and the population in the White Sea are darker. The peritoneum , the skin that lines the abdomen, is silvery, the side line contrasts brightly with the color of the sides of the body. It runs on the front body in an arch high above the pectoral fins and in the back half of the body on the middle of the side. The number of vertebrae is 51 to 55. In contrast to the Pacific and Greenland cod , the head of the cod is relatively narrow. Cod can live to be 20 years old.
distribution
Historical occurrences
“It would have been hard to imagine for the Vikings in the 10th century that the cod would disappear from the seas: They followed the cod swarms to the west on an immense scale. On their hunt for fish, they made their way from Iceland via Greenland to America. They discovered unimaginable cod grounds off Newfoundland. ... Then the English arrived, and the Pilgrim Fathers owed their survival to fish as a food. They told of the sea off Newfoundland, that one could no longer see before fish, that one could scoop them out of the water in baskets. The swarms in these stories are so dense that they slow down the boats. "
Spatial distribution
Its distribution area extends from the northern Canadian Ungava Bay along the Atlantic coast of North America to Cape Hatteras on the east coast of the United States , includes the coasts of the southern half of Greenland and extends in the European North Atlantic from Iceland , Svalbard and Bear Island to the Barents Sea , Novaya Zemlya and im South to the Biscay and also includes the North Sea and the Baltic Sea with the exception of the Gulf of Bothnia .
Way of life
Cod tolerate temperatures from 0 ° C to 20 ° C, almost any salinity from very weakly salty brackish water to pure sea water with a salt content of around 3.5% and live in different habitats from the coast to depths of 600 meters and below, but mostly between 150 and 200 meters depth. Young fish are more likely to be found in shallow water at depths of 10 to 30 meters in an environment rich in structures, in which they can hide from predatory fish, such as seagrass meadows or soils that are covered by gravel, gravel or larger stones. Adult cod prefer deeper, colder water. For a specimen that was tagged at Jan Mayen and caught again near Iceland, a diving depth of over 1000 meters was proven.
In general, cod are bottom fish and usually live at depths of 150 to 200 meters above the ground. If the conditions do not agree, e.g. B. when the oxygen level is too low, or for foraging or reproduction, they also swim pelagically in open water at depths of 30 to 80 meters. Large adult animals prefer low temperatures of 0 to 5 ° C. The location of the cod is generally determined more by the food available than the temperature. Cod migrate between spawning, feeding and wintering grounds. Migrations longer than 200 km are rare for the cod of the North Sea, the English Channel and the Irish Sea , but in the northeast Atlantic they cover distances of 800 to 900 km, while cod on the coasts of Greenland even migrate over distances of more than 1000 km. The cod of the northeast Atlantic spend most of the year in the Barents Sea and migrate to the coast of Norway to spawn. For the cod in the Baltic Sea, the Bornholm Basin is important, as it is frequently visited both for foraging and as a spawning ground.
In the western Atlantic, in the southern Gulf of Maine, the cod are driven to the coast of Labrador in summer by rising water temperatures, only to migrate south again later in winter or to visit deeper water regions. Various estuaries in Maine and Massachusetts are also regularly visited in late fall and winter . During the day, the fish are sociable and form groups that swim about 30 to 80 meters above the sea floor. At night they spread out to search for food.
Some cod groups always live relatively stationary in the same habitat. Others go on amazingly long hikes and never return to their place of birth. Their average speed is on the order of five kilometers a day. For a cod that migrated from the east coast to the west coast of Greenland in one month, however, an average speed of 25.7 km per day was calculated.
Little is known about the migrations of young cod. They may alternate between shallow water in summer and deep regions in winter. In the Barents Sea, three to four-year-old animals follow the spawning capelin to the coast in March and April and the capelin migrates to their feeding grounds in summer. As they get older, they join the adult cod to take part in the spawning migrations.
nutrition
The cod feed on a wide variety of prey, including krill , amphipods , poly-bristles , echinoderms , crustaceans , clams, and smaller fish. Cod veins feed on plankton , for young fish up to 25 cm in length, small crustaceans make up about 90% of the amount of food. As they grow in size, they are gradually replaced by medium-sized and larger decapods . Large specimens become outright predatory fish and prey on herring , capelin , haddock and deep-sea cod, which is related to cod, and cannibalistically smaller specimens of their own species. While the proportion and composition of benthic invertebrates in the diet hardly changes over the course of the year fish consumption changes depending on the season. Cod living in the ocean follow the migration of herring and capelin, while sand eels are an important part of the diet for populations living near the coast . Fish living in deep water layers prefer herrings in summer and autumn, while they prefer a mixed diet in winter and their spawning season. During the spawning season of the herring, the stomachs of the cod are often bulging with herring eggs. Plants are also occasionally eaten, including the cartilage wrack ( Chondrus crispus ). Cod eat little in the winter months and during their breeding season. Adult cod look for food at dusk and at night, while small specimens less than 20 cm long eat continuously.
Reproduction
.jpg)
Cod are sexually mature with a length of 31 to 74 cm (average 41 cm) and an age of two ( Oslofjord ) to four years (West Atlantic). They spawn once a year. The gender ratio is approximately 1: 1, with a slight overweight of females. Spawning takes place just above the sea floor of the continental shelf at a depth of up to 200 meters with a water temperature of 0 to 10 ° C, with a temperature range of 4 to 6 ° C or below being preferred. If they do not find the right water temperature there, they are likely to spawn pelagically at depths that are at the preferred temperature. The choice of spawning area also depends on the oxygen content of the bottom water.
Important spawning grounds in Europe are Lofoten and the rest of the Norwegian coast, where reproduction takes place from February to April, and the White Sea , where fish spawn from March to May. The cod living in the North Sea reproduce from December to May, those in the brackish Baltic Sea from April to the end of May in the deep Bornholm Basin (east of Bornholm ), which has a high salinity. In years with little saltwater influx from the North Sea, the reproductive success of the Baltic cod is low. The pelagic eggs then sink into deep water with little oxygen and die. The main spawning area in the northwest Atlantic is the eastern half of Georges Bank , between Cape Cod and Nova Scotia , and the sea south of the Newfoundland Bank , the second most important is the southwestern part of the Gulf of Maine between the Nantucket Shoals south of Nantucket and the Bay of Fundy . They spawn at Newfoundland Bank from April to June, in the Gulf of Maine from November to April, off the coast of western Greenland from March to June, and in the southwestern Gulf of Saint Lawrence from May to September.
The cod is one of the most fertile fish on earth. On average, a female lays one million eggs, but a five kilogram can lay 2.5 million, a ten kilogram five million and a female weighing 15 kilograms can lay 7.5 million eggs. The highest egg count was found in a 34 kg female and was nine million. The eggs are about 1.5 mm in diameter and rise to the surface of the sea. The larvae hatch after two to four weeks, depending on the water temperature, and are then about five millimeters long. Eggs and larvae are pelagic for the first 2.5 months , after which the post larvae live near the seabed. Larvae and fry grow quickly, and female fish grow a little faster than males. Cod in the North Sea and the English Channel grow faster than those living at higher latitudes. At the age of three, males are on average 56 cm long, females 59 cm, at the age of five, average lengths of 81 (males) to 85 cm (females) are reached.
The strong fishing pressure favors early sexual maturity, as cod which mature late are often caught before they spawn for the first time and so cannot pass on their predisposition. Whereas the average length of the first spawners used to be 70 cm, today it is 50 to 60 cm in the North Sea.
Systematics
Different populations of cod differ in color, size, swim bladder morphology, growth rate, spawning behavior, and preferred water temperature and salinity . G. morhua callarias has been described as a subspecies , a non-migratory population that occurs in parts of the Baltic Sea, prefers a low salinity and has a swim bladder, the front section of which is very long and the tip is shaped into a ball. Further subspecies are G. morhua kildinensis , which is only found in the relict lake Mogilnoje on the northern Russian island of Kildin east of the Kola Bay , G. morhua marisalbi in the White Sea and G. morhua hiemalis , which occurs as a migratory fish in the northern Russian Kandalaksha Bay .
Use as food fish
Among the edible fish , the cod is one of the most important sea fish and accounts for almost 30% of the world's bottom fishery. According to the FAO, the catch rose from just over two million tons in 1950 to almost four million tons in 1968 and has since fallen continuously to below one million tons in 2010.
In Germany he had between 0.3 and 2.7 percent of the per capita consumption of seafood since 2010. In comparison, its relative, the Pacific pollack ( Alaskan pollock ), and salmon accounted for up to 26 and 22 percent, respectively.
| Share of per capita consumption in percent | 2010 | 2011 | 2012 | 2013 | 2014 | 2015 | 2016 | 2017 | 2018 |
| cod | 1.6 | 2.2 | 2.2 | 0.3 | 2.7 | 2.4 | 3.2 | 2.1 | 2.2 |
Fishing method
Cod is caught on the level seabed with bottom trawls or Snurrewaden (Denmark). The latter is a ring-shaped net that is pulled in by the cutter over the bottom to an anchorage. Swimming trawls , gill nets , stationary gill nets (especially in Newfoundland ), longlines and purse seine are also used.
The Norwegian skrei, on the other hand, is caught particularly gently with hand fishing rods and longlines. Since the fishing season is limited to the months of January to April, it is also called winter cod. Its existence is not endangered by the gentle fishing methods.
Fishing areas
Most cod is caught in Iceland, the Northern European Sea , Svalbard , Bear Island and the Barents Sea . The main catcher nations are Iceland, Norway and Russia.
Stocks and exposure
Due to a wrong fisheries policy, the once huge cod stocks in Newfoundland and West Greenland can no longer be used:
- Before 1992 Canada had failed to protect the stocks despite warnings from science, so they collapsed. A fishing ban has been in place since 1992, resulting in the loss of 40,000 jobs in Newfoundland.
- In 2006, the EU did not protect the stocks off West Greenland for another year to enable them to spawn. This had similar consequences as the wrong fisheries policy in Canada and was also the main reason why Iceland did not want to join the EU.
- The European Commission has approved a ban on fishing for cod in many parts of the Baltic Sea on 23 July 2019 on the grounds that the cod stock in the eastern Baltic Sea is shrinking dramatically and a "collapse" is imminent. The ban applies until December 31, 2019.
The International Union for Conservation of Nature and Natural Resources (IUCN) classifies the cod in its Red List of Threatened Species due to overfishing as endangered ( vulnerable ) a.
Climate change will lead to strong warming of inland seas. From this, the Kiel marine ecologist Thorsten Reusch concludes : “It is clearly too warm for cod in the Baltic Sea. We assume that it could be extinct here in 50 to 80 years. "
Processing and preparation
Cod meat is sold fresh, frozen, salted or dried (as stockfish ). From his liver is cod liver oil manufactured or it is in jars or cans conserved ( cod liver ). The eggs are also marketed fresh, smoked or canned. Cod is a traditional ingredient of fish and chips , the unofficial national dish of the United Kingdom , and is also used for fish sticks used. Freshly salted in barrels, cod was long known as laberdan . In Portugal and Brazil in particular , it is sold as stockfish under the name Bacalhau . In Spain, “cortezas de bacalao”, strips of cod skin fried in sunflower oil and lightly salted, are popular as a snack .
- Examples of its use as food fish
Bacalhau ( stockfish from cod), here in a shop window in Lisbon
Cortezas de bacalao ( fried cod skin )
Fish and chips , here with cod fillet in beer batter
Fish soup with cod
Trivia
Every year in March in Svolvær, Norway, the world championships in cod fishing are held. In 2012 the winner caught a fish weighing 18.3 kilograms.
literature
- The cod (stockfish, Gadus Morrhua L.) and its catch . In: Illustrirte Zeitung . No. 32 . J. J. Weber, Leipzig February 3, 1844, p. 86-89 ( books.google.de ).
- Bent J. Muus, Jørgen G. Nielsen: The marine fish of Europe in the North Sea, Baltic Sea and Atlantic. Kosmos, Stuttgart 1999, ISBN 3-440-07804-3 .
- Daniel M. Cohen, Tadashi Inada, Tomio Iwamoto, Nadia Scialabba: Gadiform fishes of the world (Order Gadiformes). An annotated and illustrated catalog of cods, hakes, grenadiers and other gadiform fishes known to date. FAO species catalog. No. 125, Volume 10, Rome 1990, ISBN 92-5-102890-7 .
- Mark Kurlansky: Cod - the fish that changed the world. List Taschenbuch, Ullstein Taschenbuch Verlag, Munich 2000. ISBN 3-548-60115-4 .
Web links
- Gadus morhua on Fishbase.org (English)
- Gadus morhua at the Marine Species Identification Portal.
- Gadus morhua at the Fisheries and Aquaculture Department of the FAO .
- Skrei ( Memento from January 12, 2015 in the Internet Archive )
- Cod in the fish lexicon of the fish processing company Deutsche See
Individual evidence
- ↑ Fish information center: Cod (PDF)
- ↑ Overview "Fish of the Year" in Germany. German Fishing Association, accessed on February 26, 2018 .
- ↑ Flemming T. Dahlke, Martin Butzin, Jasmine Nahrgang, Velmurugu Puvanendran, Atle Mortensen, Hans-Otto Pörtner , Daniela Storch (2018). Northern cod species face spawning habitat losses if global warming exceeds 1.5 ° C. Science Advances , 4 (11), doi: 10.1126 / sciadv.aas8821
- ^ Friedrich Kluge: Etymological dictionary of the German language.
- ↑ Montgomery Schuyler Jr .: The Etymology of the Dutch Word “Cod,” in: The Journal of Germanic Philology. Vol. 4, No. 1, 1902.
- ^ Entry Cod , in: Wolfgang Pfeifer (Hrsg.): Etymological Dictionary of the German Language .
- ↑ Duden Etymology .
- ↑ I caught the world's biggest-ever cod! German angler smashes world record for endangered fish by landing 103lbs-specimen 5lbs heavier than the last. Daily Mail, May 13, 2013, accessed May 13, 2013 .
- ↑ A fish makes history - the cod. In: 3sat.de , broadcast on November 25, 2010.
- ↑ Fischwirtschaft - Facts and Figures 2019 (PDF) Retrieved on September 4, 2019 .
- ↑ Collapse in the fishery. In: greenpeace.de
- ↑ Ban on fishing for cod? Why EU fisheries ministers ignore advice from biologists. In: deutschlandfunk.de , December 20, 2006.
- ↑ europa.eu: Immediate fishing ban for cod in the Baltic Sea
- ↑ Gadus morhua in the endangered Red List species the IUCN 2007 Posted by: J. Sobel, 1996. Accessed December 1, 2012th
- ↑ Kiel expert: The Baltic Sea is getting too warm for cod. In: zeit.de , June 12, 2017.
- ↑ Berliner Zeitung of March 16, 2013, page R1.
Brook Loach (1984) | Bitterling (1985) | Schneider (1986) | European mud lamb (1987) | Brook lamprey , river lamprey (1988) | Bullhead (1989) | Brown trout (1990) | Minnow (1991) | Atlantic salmon (1992) | Cod (1993) | Nose (1994) | European eel (1995) | Sea trout (1996) | European grayling (1997) | Strömer (1998) | North Sea Bill † (1999) | Atlantic salmon (2000) | European sturgeon (2001) | Burbot (2002) | Barbel (2003) | Allis shad (2004) | Brown Trout (2005) | Bullhead (2006) | Tench (2007) | Bitterling (2008) | European eel (2009) | Crucian carp (2010) | Grayling (2011) | Lamprey (2012) | Trout (2013) | European sturgeon (2014) | Huchen (2015) | Pike (2016) | Flounder (2017) | Three-spined stickleback (2018) | Atlantic salmon (2019)