Few people know that one of the varieties of black caviar is produced by Russian sturgeon. But in fact, the color of their larvae is not black at all, but rather light brown or olive. Sturgeon caviar is very expensive - the price is second only to beluga caviar. The product is difficult to access due to the small population and difficulties in breeding. And the sturgeon family is one of the most ancient: representatives of this species existed even during the time of dinosaurs.
Description
Sturgeon live on average about 46 years and during this time they only have time to go to spawn a few times.The reason for the low reproduction rate is long puberty: females are able to give birth to their first offspring at 10-16 years of age. Moreover, this feature is also inherent in all other representatives of the sturgeon family.
Habitat
Adult Russian sturgeon are found mainly in the European part of the Russian Federation, namely in the Caspian, Black and Azov seas. But the preferred spawning grounds for sturgeon are the freshwater reservoirs of the inflowing rivers: the Don, Dnieper and Danube, the rivers of Bulgaria, Georgia and Azerbaijan, and the largest of them is the Volga. Here, before regulation occurred in 1952, sturgeons rose 400-500 kilometers upward.
What does a fish look like?
The average weight of a Russian sturgeon is 15-25 kilograms, and it is impossible to say what the maximum figure for this species is: sturgeon weighing 80 kilograms are occasionally found, and in some cases, individuals up to a ton are found in rivers! The body of sturgeons is muscular with an elongated head and a flattened snout. They have no bones or scales - the spine consists of cartilage, and the role of natural armor is played by bone plates in the form of spikes. Sturgeon spines are arranged in five parallel rows and cover the body.
The color of the sturgeon is heterogeneous: brown above, light below, gray-yellow in profile. One of the outstanding organs of touch of sturgeons is their antennae in the form of four skin processes located under the snout. The receptors are used to scan the composition of the bottom when searching for suitable food.
Lifestyle
The favorite place to hunt is not far from the bottom, and preferences change as you grow older:
- the fry feed on zooplankton - daphnia, worms, small crustaceans;
- young animals eat shrimp, snails and other benthic invertebrates;
- The diet of adult sturgeons is supplemented with small and medium-sized fish - sprat, sprat, gobies, mullet, and herring.
The fish becomes voracious before breeding, and during the spawning period, even for a month, therefore, on the contrary, it does not eat, since it stops hunting altogether. Maintaining strength at this time is due to eating algae.
As noted above, reproduction of sturgeon offspring occurs in the fresh waters of Russian rivers, the time is the first days of July. The terrain chosen is rocky or sandy, the water flow speed is average. At one time, the female lays 800 eggs, after which she immediately rolls into the sea. The larvae lie motionless at the bottom for 3-4 days before a fry emerges from them, which, when it reaches a length of 2-8 centimeters, is also removed from the river. It has been noted that the bulk of caviar is reproduced by females, whose age is 15-25 years - that is, no more than 4 cycles in their entire life, considering that the interval between sturgeon matings is 2-3 years.
Fish facts
In the 18th century, this species was very common in Russia - its representatives were found even in the Moscow River. Unfortunately, over the past 50 years, the sturgeon population has been rapidly declining, for two reasons:
- The construction of hydroelectric dams has blocked access to many spawning sites. Natural marine spawning grounds have also been noticeably reduced due to large-scale construction of coastal dams.
- Poaching - the bulk of the sturgeon business is in the shadows. For example, in Russia, out of 225 tons of caviar, only 10 are mined legally.
The situation with sudden changes in the fauna of the seas has been repeatedly discussed in world environmental organizations.As a result, industrial fishing and production of sturgeon has long been prohibited in all countries except Russia, Turkmenistan, Azerbaijan, Iran and Kazakhstan. The endangered species is also protected by the Convention on International Trade in Endangered Wildlife. And in 1996, the fish was included in the International Red Book with the assignment of category EN, which means - on the verge of extinction.
To preserve natural resources, a method for the industrial production of sturgeon has been developed. Moreover, artificial conditions involve keeping fish in warmer water and with more intense nutrition, which reduces the age of sexual maturation of females down to 3-4 years. Unfortunately, all of the above measures are not enough to somehow improve the situation, that is, the population is currently still declining.
If the trend towards extinction continues, perhaps soon the species will simply cease to exist, and sturgeon will no longer be found in natural conditions.
