Sturgeons are quite large ancient fish that are of great value to humans. The fish has many features, but because of them it is often faced with a large number of problems that put the further existence of sturgeons into question.
Description and appearance
The species of sturgeon fish is one of the oldest on the planet, which has survived to the present. Its representatives appeared in the Cretaceous period (85 million years ago) and are invertebrate chordates, with characteristic bony scales on the body.
Sturgeons grow up to 6 m in length and can weigh up to 850 kg, which makes them quite large creatures. They can adapt to any conditions, due to which they live in many rivers and seas.
The head of the sturgeon is flattened, has a mouth extended forward, below which there are several antennae. Most species have a gray color with a light belly.
Sturgeon body
On the back of the fish, a chord is strongly visible, presented as a continuous connection of small spikes. On the sides there are large hard plates protecting from the teeth of other predators.
The tail is divided into two fins, with the upper elongated more strongly than the lower. The head is flattened, the mouth is located under the upper jaw, at eye level.
External features of the sturgeon
Depending on the place of residence, the fish has a different color, but almost always it comes down to a gray top and a light belly. There may be small brown areas on the sides.
The upper and lower fins are not located in the center of the body, but practically close to the tail. The body is covered with spines and bone growths. The mouth is located far from the tip of the muzzle, has no teeth, but can be pulled forward to capture food.
Interesting fact: the gills of the fish are oval cartilages, from the formation of which the formation of full jaws began.
Head and teeth
Only young sturgeons have teeth, but gradually they disappear. Adults have smooth jaws. The head is separated from the body by slots, inside which you can see the gills. The nose of the sturgeon is extended forward and slightly dulled.
Since this species is used to swimming along the bottom and eating small crustaceans and insects, the mouth is located in the lower part of the body. This eliminates the need to bend your head down to grab prey. Four smooth antennae are placed in front of the mouth opening, helping to find food.
Body color
The color of the fish largely depends on the reservoir where it lives. Connoisseurs can determine by eye which river the sturgeon was caught from just by looking at it. The light belly of an individual can have a tint from yellowish to white, the lower fin is also colored in the same color.
The back and sides of the fish are dark in color, and their hue varies from blue to green. Such differences and the binding of a particular color to the habitat allow you to track the travel of various individuals.
Sturgeon scales
Sturgeons lack scales on the body. It is replaced by bone plates that completely cover the body. They are arranged in rows: one is on the back, two on the belly and one more on the sides. The plate has a certain size depending on the location. In adults, their number can reach up to 40 pieces.
Dorsal and caudal fins
At the base of the head are pectoral fins. They are always parallel to the bottom and do not bend to the body. The remaining fins are located near the tail of the fish. All of them consist of bone spokes connected by a film. The first strip at the beginning of the fin is thicker than the others and consists of bone material, while the rest are ordinary seals.
Interesting fact: if you cut a bone spoke from the base of the fin, then by section you can determine the age of the individual.
Habitat - where does the sturgeon live?
Sturgeon can be found in North America, Europe, Russia, Southeast Asia and other countries where there are reservoirs with favorable conditions.
Several species of this fish live on the territory of Russia, and each one has a specific habitat:
- sterlet and stellate sturgeon huddle in the Black, Caspian and Azov seas;
- Beluga prefers the Caspian and Black Seas;
- Kaluga can be found only in the Amur River;
- Russian sturgeon is a river fish and lives in the Danube, the Caspian, the Urals and the Volga;
- Siberian sturgeon lives in Lake Baikal and in the rivers of Siberia.
From time to time, different species can wander into foreign territories, but eventually come back.
Habitat
Some species of sturgeon are migratory fish, live in the seas, but go to spawn in the rivers flowing into them, where they spawn. Most of the population falls on European, North American and Asian reservoirs.
For a long time of existence, they are perfectly adapted to low temperatures, so they feel great in cold water. A prolonged lack of food is also not a problem for sturgeon. His body is able to work in emergency mode and consume little energy for a long time.
The fish spends most of the time at the bottom, choosing a depth of 2 to 100 meters. To spawn, individuals swim from the seas to rivers, and they can travel huge distances to find favorable conditions.
Freshwater sturgeon species live in rivers and lakes, and they do not need to sail from the seas for spawning. Such individuals are more finicky in environmental conditions, and the presence of clean water is a prerequisite.
How much sturgeon lives
I live fish long enough compared to other underwater inhabitants. Sterlet and stellate sturgeon can exist in vivo for up to 30 years. Russian sturgeon can last up to half a century, and the beluga is a record holder, which, with proper care and a favorable climate, can live up to 100 years.
What eats
Sturgeon is a predatory fish, but due to lack of teeth it is able to eat only a small fish. Most of the diet is made up of small crustaceans and insects that move along the bottom. During a lack of food, individuals can switch to algae, but they are reluctant to do so.
Interesting fact: Cases have been reported when large sturgeons attack waterfowl.
Before spawning, fish begin to eat everything that catches the eye. They accumulate mass so that the body's resources are enough for carrying thousands of eggs. Putting them aside, the female begins to gain mass again.
Features of sturgeon life
After the end of winter, migratory species depart from the seas to rivers for spawning. Freshwater individuals hibernate right on the habitat, after which they prepare for the production of offspring.
As territories for living fish choose water bodies fast flow. They practically do not float to the surface, most of the time moving along the bottom. Before the onset of cold weather, the sturgeon goes to spawn and tries to eat as much food as possible. But before the onset of winter, individuals begin to look for holes and crevices at the bottom, where you can wait out the winter.
With the onset of frost, when the rivers are covered with ice, the fish falls into suspended animation and practically does not move. At this time, her body works very slowly, so she does not need food.
Natural enemies
Sturgeons live in places where there are no other large predators. Because of this, they have virtually no natural enemies. Any fish encountered along the way is not able to gnaw bone plates, which is why, in principle, no one attacks the sturgeon.
The only creature to be afraid of this fish is a person. For several centuries people have been actively breeding and catching different types of sturgeon in order to obtain valuable meat and black caviar.
Also, this fish is very finicky to environmental conditions.If she swims in polluted waters, then she runs the risk of catching many diseases that cannot be cured. That is why artificial breeding is expensive because it requires the installation of special equipment.
Breeding, offspring - spawning
Most sturgeon species mature very slowly. Males are able to produce offspring only by the age of 13, and females can even lay eggs closer to 18. Fishes go to spawn in the spring, when winter colds go away.
After leaving suspended animation, individuals leave for rivers with a strong current, where they will spawn. Before this, the females absorb food in large quantities, so that later they do not eat for a long time and engage in bearing children.
Interesting fact: Scientists have found that in the Dnieper and the Don, sturgeons mature much faster than in other rivers of Russia.
To lay eggs, the female swims in places with a strong current. The eggs stick to the pitfalls with the help of a special adhesive substance that covers the shell. Within a few days, fry mature within. Having been born, they for a long time remain at the place of their birth, feed on plankton and small organisms.
Growing up to 30-35 cm in two years, young individuals swim from the rivers and go to the habitats of their own species. There they join the flock and begin to lead a cyclical lifestyle, eating, wintering and going to spawn as they become ready.
Hybrids
As new hydroelectric power plants are being built every decade, and sturgeons cannot live near them, their habitat is gradually decreasing. Because of this, different species are forced to live side by side, which leads to a cross that provokes the appearance of hybrids.
Modified fish perfectly adapt to environmental conditions. Moreover, a person is personally involved in the creation of hybrids, since they have more valuable caviar and meat. The most popular is the bester - the result of the merger of the beluga and sterlet. These individuals have a lighter color, grow well and develop. Also a distinctive feature is their small size. Adult besters grow to 170 cm and weigh no more than 30 kg.
Shovels
A rather unusual type of sturgeon, common in American rivers. Its distinguishing feature is a flat, elongated nose, similar to a shovel. At its base is a rounded mouth. The largest population lives in Mississippi and is divided into ordinary, dark-colored, and white.
In structure, the body is similar to the body of the remaining sturgeons, but the fins are able to serve as suction cups and help to stay in place with a strong current.
Interesting fact: the eyes of the shovel are tightened by the skin, but this does not prevent them from orienting themselves in space due to the developed organs of touch.
In Russia, there is a separate species - pseudopathy. He got this name because of the small size, which often does not exceed half a meter. Its representatives can be found in the Amu Darya and Syr Darya.
During spawning, shovels do not float at the mouth of the rivers, but they spawn right at the place of residence.
Types of sturgeons
At the moment, scientists distinguish 17 main types of sturgeon, which have certain characteristics. Also among them are representatives of hybrids that appeared during the merger of two individuals of different types.
Any species can be easily distinguished from ordinary fish thanks to a flattened muzzle and bone plates on the body. Almost all sturgeons are finicky to the environment and live in clear water. Any pollution can provoke massive relocation.
5 types of sturgeon breeds in Russia
Five species of sturgeon live on the territory of the Russian Federation. Scientists are trying to monitor their numbers and protect them from extinction.
Russian sturgeon
A distinctive feature of the fish is a mustache, located not at the eyes, but practically on the nose itself.Russian sturgeon is found in the Volga, Dnieper, Don, Kuban and other rivers. It can also huddle in the seas where they flow.
The species does not grow to large sizes, and the weight of individuals does not exceed 25 kg. The body is dark gray, the belly has a brownish tint.
Due to the increased interest of a person in this species, its number is gradually decreasing.
Sterlet
A large species living in the Azov, Black, Caspian and Baltic Seas and in the flowing rivers. It boasts a large size. On the territory of the Russian Federation, its artificial production is developed.
Shrenka (Amur sturgeon)
It occurs in the Amur River, but recently its number has seriously decreased. A distinctive feature is the high location of the front fin, which is tight to the head.
Kaluga
Large sturgeons with a greenish color. During spawning, they are able to lay up to a million eggs, but produce offspring once every 5 years.
Stellate sturgeon
It has a long body, nose is very elongated forward. The case has a dark brown spine dotted with spikes. It feeds mainly on small fish. It is found in the Caspian, Black and Azov Seas.
Population and species status
Now most of the sturgeon species is on the verge of extinction. The reason for this was the deterioration of the ecological situation and active fishing in order to extract meat and caviar.
Over the past decades, many countries have introduced bans on the capture of sturgeon. Special reservoirs were created where the fish are artificially grown and released into the wild.
Sturgeons and the reasons for their extinction
The fish got used to clean water, but now many hydroelectric power stations are being built. Waste is also dumped into rivers. All this reduces the population. Man doesn’t mind eating meat and caviar of sturgeon. Because of this, poachers catch fish in large numbers, waiting for them at the estuaries during spawning.
Fisheries
In the last century, sturgeon was caught in large quantities in Russia. So people got meat and caviar, eaten. But in connection with a sharp decline in the population in the early 2000s, a ban on the capture of this fish was introduced. Now it is artificially removed for commercial purposes in special reservoirs.
Heraldry
Sturgeon is often found on the arms of various cities. For example, fish flaunts on the symbols of the village of Zhigansk, located in Yakutia. Baltiysk from the Kaliningrad region was no exception. Also, the image of the sturgeon is used by the city of Sarapul and the Saratov region.
