Sensational discovery in Antarctica: where the largest fish breeding area in the world was found, with over 60 million Icefish nests. This real nursery is spread over an area of over 240 square kilometers, according to the German research expedition of the Alfred Wegener Institute.
The results of the study are published in the journal Current Biology: the shoot showed an endless expanse of nests, each controlled by a fish. These are small holes 15 centimeters deep and 75 wide, each of which contains about 2,000 eggs, between 535 and 420 meters deep, in the Weddell Sea.
Director of the Alfred Wegener Institute, Antje Boetius, said: "Now that we know the location of this extraordinary breeding colony, it is vital to ensure that no fishing is carried out there. So far the remoteness and difficult conditions have protected the area.
but with increasing pressures on the ocean and polar regions we need to be more ambitious in marine conservation measures. "
Icefish: what a fish it is
Icefish are among the few fish that live in the waters of Antarctica.
These fish manage to survive in Antarctic waters, the temperature of which fluctuates between -1 and -2 ° C, as their blood has a reduced viscosity. To reduce the viscosity of the blood the cannictids have evolved by eliminating both red blood cells and hemoglobin, taking advantage of the fact that in low temperature water oxygen is much more soluble and it tends to be absorbed by the gill blood more easily.
Furthermore, these fish carry out skin respiration: they have a dense network of capillaries near the skin, devoid of scales, where a further exchange of gases with the environment can therefore take place. They have an elongated body that tapers towards the tail.
The head is large with a pointed muzzle and very large eyes. The pectoral fins are well developed, the ventral fins are long and rigid, the anal fin is thin and barely visible, the tail broad and muscular. On the back they have two dorsal fins, the first with strong developed rays.
Cannictidae lack a swim bladder. Icefish are unusual in many ways, lacking scales and having transparent bones, but what most sets them apart among vertebrates is their hemoglobin-free white blood. Evolutionary adaptations essential for their survival have been found in the genome of an icefish species (Chaenocephalus aceratus).
Some were common to red-blooded fish living in Antarctic waters, such as the presence of additional genes involved in protection from freeze damage, such as anti-freeze glycoproteins and zona pellucida proteins. Others were more closely related to the lack of red blood cells, such as genes than encoding enzymes active in the control of cellular redox state, including members of the sod3 and nqo1 gene families that protect tissues from highly reactive free oxygen in the blood.