Atlantic cod

Atlantic cod (Latin name: Gadus morhua) is a famous fish from the cod family. In many countries it has its own name.

 Content

• What does cod fish look like?
• Distribution area of cod
• Biology of Atlantic cod
• Atlantic cod species
• Commercial fish cod
• Growing cod in mariculture

 

What does cod fish look like?

The body length of cod reaches 1.8 m; In the cod fishery, cod with a length of 40–80 cm and an age of 3–10 years predominate. Cod's eyes are relatively small. Cod has 3 dorsal fins, 2 anal fins, the base of the first anal fin is located behind the space between the first and second dorsal fins. The cod has a small, fleshy barbel on its chin. The color of the back of the cod is from greenish-olive to brown with small brown specks; the belly of the cod is white.

The cod's mouth is large, the upper jaw protrudes noticeably forward. The lateral line is continuous with a curve above the pectoral fin.

Previously, catches included specimens up to 90 kg. Currently, there are individuals with a maximum weight of up to 45 kg, body length reaches 1.8 m.

Distribution area of cod

The distribution range of cod covers the temperate region in the Atlantic Ocean, forming several geographical subspecies of cod: Arctic cod, Greenland cod, Norwegian cod, White Sea cod, Baltic cod and other types of cod, a total of 17 species of cod. In the eastern part of the Atlantic Ocean, Atlantic cod is distributed from the Bay of Biscay to Spitsbergen and the Barents Sea; in the western Atlantic Ocean from Cape Hatteras (North Carolina) to Greenland.

 

Biology of Atlantic cod

Cod is found from the coastal strip to the continental shelf; in the open sea over great depths, cod is rare. Cod spawns once a year. The life cycle of cod is tied to sea currents in the Atlantic.

Atlantic cod species

Atlantic cod (subspecies Norwegian cod) breeds off the coast of Norway, and cod fatten in the Barents Sea and in shallow waters off the island of Spitsbergen. The main spawning grounds for Norwegian cod are located off the Lofoten Islands, which belong to Norway. Cod spawns in March - April at a depth of up to 100 m; cod spawns on the border between the warm waters of the Atlantic and the colder waters of the Norwegian fjords. Fertilized cod eggs are picked up by currents that carry them north.

Hatched cod larvae feed on plankton. Part of the juvenile cod reaches Bear Island with the current, but a large number of juveniles are brought with the North Cape Current to the Barents Sea. By July, cod fry, drifting north, reach 72-73° N. latitude, and juvenile cod drifting east reaches the Kola meridian (33° E). In September, juvenile cod reach the eastern regions of the Barents Sea, where the cod switches to a bottom lifestyle. In the first two years, Atlantic cod feeds on small crustaceans. From the age of 3, Atlantic cod becomes a predator and the cod begins to make quite noticeable migrations.

What does cod eat? The diet of Atlantic cod in the Barents Sea consists of three types of fish: herring (usually juvenile herring), saury and capelin. In summer, Atlantic cod often feed on crustaceans from the family Euphausiaceae; Sometimes cod eat bottom fauna, usually bivalves. Atlantic cod also feeds on juvenile cod and smaller relatives.

When does cod spawn? At the age of 8-9 years, cod reaches a weight of 3-4 kg, Atlantic cod goes to spawn for the first time. In September - October, Atlantic cod gather in huge schools and begin to migrate back to the Lofoten Islands. Cod travels over 1,500 km to spawn in 5-6 months, covering 7-8 km per day. Female cod remain on the spawning ground for several weeks; a female cod spawns 2-3 portions of eggs, up to 9 million eggs from one female; the same number of males remain at the spawning ground, fertilizing the females. Spawned cod return to their feeding grounds to fatten. Norwegian cod lives up to 20-25 years.

Some subspecies of cod (White Sea cod, Baltic cod) have adapted to life in desalinated seas. White Sea cod and Baltic cod do not make long migrations for spawning and cod matures earlier, at 3-4 years of life. There are also two lake forms of cod. In Lake Mogilny, which is located on the island of Kildin, in the Murmansk region (Gadus morhua kildinensis), as well as in Lake Ogak located on Baffin Island (Gadus morhua ogac or Gadus ogac), cod lives, penetrating into these lakes at the time when they were still connected to the sea. Freshwater cod is small in number and does not play a major commercial role.

Commercial fish cod

Atlantic cod is one of the most important commercial fish.

Cod liver, rich in fat (fat content up to 74%), is a source of valuable fish oil - oil that is obtained from a large liver weighing 1.3 - 2.2 kg).

Cod is one of the most popular fish in the cuisines of many countries around the world, from Portugal, where There are 365 dishes and up to Russia and Canada. White dense cod meat has a good taste, it contains 18-19% protein, 0.3-0.4% fat and is considered a dietary product. Cod does not have small bones, so it is easy to turn into a good fillet. Cod goes on sale chilled, frozen, salted and smoked (hot smoked).

Cod caviar is harvested in Scandinavia.

The cod catch is so large that only every twentieth female can spawn; the remaining 19 end up in a fishing trawl on the way to the spawning ground.

Growing cod in mariculture

The importance of cod is so great that it began to be grown in cages in Scotland and Norway.

Atlantic cod began to be cultivated in Norway in 1884, releasing larvae to increase commercial stocks. The country currently hosts the world's largest hatchery, with 167 tonnes of cod produced in 2000. The intensive development of cod farming is associated with a continuing decline in catches, and the production of juveniles will contribute to the growth of mariculture volumes. Fry raised in one large hatchery will be able to support cod production in quantities comparable to the fishing season in the Lofoten area.

In 2002, about 3 million units were received. young In 2004, 9.0 thousand tons of cod were grown from it. In Norway, cod breeding is carried out in 25 hatcheries with a total capacity of 85 million pieces. young It is expected that cod production volumes will amount to 400 thousand tons by 2015, since there are a sufficient number of built hatcheries.

Despite the fact that investments in cod farming are constantly growing, knowledge about the cultivation of larvae of cold-water marine species is still insufficient, farmers do not have experience working with delicate larvae of marine fish, so it will take a lot of time to train them and master the biotechnology of cod farming.

In addition to Norway, cod mariculture is developing in the UK, where 3.6 thousand tons were grown in 2004. Interest in cod mariculture is caused by a 30% decrease in the volume of its global catch since 1997. According to FAO, by 2015 the total production of farmed cod may reach 1-2 million tons. The main barrier hindering the development of this area of marine fish farming is the cultivation of viable juvenile cod.

The length of time to raise cod fry ready for placement in cages is 8 months. Cod spawners are kept in cages at the hatchery station. By regulating the photoperiod, it will be possible to produce offspring 5 times a year. If the natural period for obtaining cod eggs is February, March and April, then with light exposure it will be possible to obtain eggs at any time of the year in order to better use the capabilities of the plant. This year-round reproduction gives this method an advantage over ocean cod fishing, where the fishery is dependent on the natural spawning season. It becomes possible to obtain cod fry for rearing in cages throughout the year. The biotechnology required to farm cod is similar to the biotechnology required to farm salmon. It is believed that cod is easier to breed and raise than salmon because its entire life cycle takes place in salt water.