GENUS GADUS MORHUA
“Cod” is the common name of different Gadus species even though some of the same genus might be called different way. The most common species is the Atlantic Cod (Gadus morhua or common cod) and it is one of more than 60 species from the same migration fish family. Gadus morhua lives in the cold Northern seas. Cod is generally a small fish even though a few of them can reach the hundred kilograms and 2 meters long. It feeds on small fish like herrings. Etymology, it casts doubt on the origin, although RAE (Royal Spanish Academy) stands that it derives from Euskara’s word (bakailao), which in turn refers to Dutch (bakeljauw), which is a variant of kabeljauw, explaining the French word cabillaud that refers to fresh cod versus dry cod (morue).
It is a robust fish, with long body, a strong and long barbel and small eyes. The upper jaw exceeds the lower one. It has three dorsal fins very close to each other at the base of the body. The first one is round. It has two anal fins with rounded edges. The caudal fin is straight and the ventral fins do not reach the anus. The lateral line continues until the start of the tail. It is marked, and has a little curve above the pectoral fins until the lower half of the second dorsal fin, then it remains straight. These fish are generally medium to big size. Normally, they are bearded on the lower jaw like catfish.
Its body has a fusiform shape and its weight and size can vary depending on the species. Atlantic cod can reach 2 meters long and 96-100 kilograms, even though their weight is normally 5-12 kilograms. Their colour can vary according to the habitat. On seaweed areas they are reddish coloured. When they are on seagrass meadows they look more like greenish. And on sandy bottomed areas or in deep water they are light grey. The body is covered by dark spots, specially young fish. It has a reticulated reddish colour, a whitish belly and a pale lateral line.
They are cold water species that are mainly located in the North Atlantic Ocean and in the Western and Eastern Pacific Ocean. Gadus Morhua is in both sides of the Atlantic Ocean., from United States area to Northern Europe. They can be found in the Baltic Sea, in the Barents Sea and in the North Sea. They live from deep water areas to shallow coastal waters.
FEEDING AND DIET
Adults diet is mainly carnivorous, and species like Atlantic Cod are large predators. Some of their most common preys are whitings, haddocks, herrings, sprats, crabs, lobsters, mussels, squids and some other molluscs. Curiously, certain cod species commit cannibalism and eat young individuals of their own species.
Cod can migrate seasonally. In the case of Atlantic Cod, it follows the warm currents to spawning and breeding areas in company of other individuals. It is possible to find it at 600 meters deep, but it is not a problem for it to approach the shallow-water coastals. They tend to be gregarious fish. That is why they are found in large fish shoals.
The life cycle of the cod species is very odd. Males court females by swimming exhibitions, standing out their fins and swimming on their back under them while both of them move in circles. If a female accepts a male, she allows fertilisation. Then, she lays some eggs. An adult female is capable to lay 5 million eggs, but only a few of their occupants survive in the future and reach adulthood. Eggs hatch in 8-23 days after laying. Then, 4 millimeter larvas that will rapidly increase in size will emerge. At the age of 3-4 years old, the young fish are already around 50 centimeters long.