Sturgeon species of fish. Sturgeon (fish): photo

Predominantly, sturgeon species live in sea salt water, and spawn in fresh water for spawning. The smallest dimensions are allocated to representatives of sterlet, which on average have sizes from 30 cm to 1 m and weight from a half-kilogram to 4 kg. The largest species of the species is the beluga, which reaches 2 tons of mass and 9 meters in length.

Today, sturgeon fishing is the world's largest fishery. In addition to meat, this species is still valuable with its caviar. During spawning, fish are prohibited. But poaching flourishes everywhere, although it is actively fighting.

External characteristics and structure

Representatives of sturgeon - one of the largest fish in the water expanses of rivers and seas, they have an elongated body that is covered with five rows of bone scutes: 1 on the back, 2 on the sides and 2 on the belly. Between them there are bone plates. Sturgeon is a fish with an oblong cone-shaped snout that looks like a shovel. Bottom of the head are the fleshy lips of the mouth, which in several species has a crescent shape and is also located on the sides. At the bottom of the muzzle are four antennae. The jaw has a retractable shape without teeth.

The radial fin on the breast is considerably thickened and has the appearance of a spine, the dorsal is slightly pushed back. The swim bladder is located under the spine and is connected to the esophagus. Bone skeleton has an invertebrate, cartilaginous structure with preservation of a chorda. The membranes of the 4 gills are attached to the throat and merge on the throat, and there are also 2 accessory gills.

general information

In most cases, all sturgeon species migrate to freshwater sources in shallow water at the moment of spawning. Their population is quite prolific, and already enough adults and large individuals can produce millions of larvae. Spawning occurs in the spring. It should be noted that some species, other than spawning, enter rivers and wintering waters. They dwell mainly on the bottom of water bodies, feed on small fish, worms, mollusks and insects.

Sexual maturation

The family of sturgeon, the list of which includes about two dozen varieties, is represented mainly by long-livers. The period of the individual's readiness for the spawning occurs in different ways depending on the habitat and the type of fish. At this time, you can observe how the shallow water of some fresh rivers is swarming with representatives of sturgeon. After spawning, the spawning individuals descend the river in the sea, increase in size, develop. Next year they again go to spawn.

The growth of sturgeon, like ripening, is very slow. Some species are ready for reproduction only at the age of 20 years. In females puberty occurs in the period from 8 to 21 years, in males from 5 to 18 years. But with respect to weight, we can say that sturgeon species are the fastest growing inhabitants of water bodies. The sturgeons of the Dnieper and Don are the fastest reaching puberty, much longer - the inhabitants of the Volga.

Spawning

Not all female sturgeon spawn every year. Only the sterlet breeds annually. Representatives of sturgeon spawn in the spring and summer season in the fresh waters of rivers with fast current. It has an adhesive structure, so it is perfectly attached to the flagstone or pebbles.

Fry

The larvae that appear from the eggs have a yolk sac, which causes an endogenous feeding period. Self-eating external food fry can by the time the endogenous bubble is completely absorbed. Then comes the exogenous period of active nutrition. After that, the fry can stay in the river waters, but often the larvae slide into the sea in the summer of the same year. So the sturgeon breeds. Photos of their various representatives can be found in this article.

Feeding fry

The first food for sturgeon fry is zooplankton, for example, daphnia. After they begin to eat the representatives of the crustaceans:

* Gammarides,

* Chironomids,

* Mysids.

The exception is the predatory beluga fry, which do not have a yolk sac, and even during the stay in the river they begin to eat independently.

Further development of sturgeon to sexual maturity occurs in sea waters. The sturgeon representatives are divided into spring and winter species. For the first habitual entry into the rivers in the spring. Spawning occurs almost immediately. Winter crops also enter the river from autumn, spend the winter, and spawn next spring.

Classification of the sturgeon family

Initially, two species of sturgeon were identified:

* Sturgeon;

* Skafirins.

All of them totaled about 25 varieties of fish, which were found only in temperate latitudes: Asia, Europe and the north of America. Over time, the population of some of them disappeared.

Kinds

Sturgeon species of fish are very popular in the fishery. Today, 17 species of sturgeon species are known. The most popular types are:

1. Beluga is the most ancient species of freshwater fish. Its life cycle can last 100 years. The largest beluga can reach 5 m in length and have a mass of 2 tons. The fish's body looks like a torpedo shape, covered with protective bone plates in 5 rows, dark gray on top and white at the bottom. From the bottom of the muzzle there are tendrils that provide a sniff to the fish, and a mouth in the shape of a sickle. Females are larger than males. Beluga is a predator, which mostly feeds on anchovies, gobies, herring, roach and hamsa. Caviar is thrown by females once in 2-4 years in the spring.

2. Russian sturgeon - a fish with a spindle-shaped body with a short blunt snout. Antennae located at the end of the mouth. Most often the fish has a greyish-black color on top, greyish-brown sides and a white belly. Russian sturgeon reaches a maximum of 3 m in length and can weigh up to 115 kg. At the same time the life cycle reaches 50 years. In nature, sturgeon can form crossbreeds with sterlet, beluga, thorn and stellate sturgeon. This happens very rarely, but similar hybrids can be found. Fish habitat: Azov, Caspian and Black Seas.

3. Siberian sturgeon. The body of the fish is covered with numerous fulkrami and bone plates, the mouth is retractable. The teeth of this fish are absent. In front of the mouth are 4 antennae. Habitats of Siberian sturgeon: the basins of the Yenisei, Ob, Lena and Kolyma. Maximum fish grows up to 3 m in length, reaches a weight of 200 kg and can live up to 60 years. Spawning occurs in the middle of summer. The food of the sturgeon is provided by organisms that live on the bottom of the river: mollusks, amphipods, polychaete worms and chironomid larvae.

4. Sevryuga lives in the basins of the Azov, Black and Caspian seas. Fish stellate is winter and spring. The elongated body of stellate sturgeon is characterized by the presence of a long nose, a convex forehead, narrow and smooth antennae and a weakly developed lower lip. Sideways and from above the body of the fish is covered with a dense cover of scutes. The back and sides are bluish-black in color, and the belly is white. Stelluga rarely reaches more than 5 m in length and 50 kg of weight.

5. Sterlet - one of the smallest fish among sturgeon, it reaches 1.25 m in length and weighs up to 16 kg. It has an elongated narrow nose, long antennae that reach the mouth, the adjacent scutes along the sides and the lower lip divided in two. In addition to the usual sturgeon plates on the body, the sterlet has closely-connected scutes on its back. Depending on the habitat, the fish may have a different color, but often its back is grayish-brown in color, and the belly is yellowish white. Fins everywhere gray. Also, the sterlet is stubborn and sharp-pointed. Fish are found exclusively in the north of Siberia.