Volga sterlet: what kind of fish is it, its size, where it lives and what it eats, spawning features
The sterlet, a member of the Acipenseridae family, is believed to be one of the prehistoric fish species preserved on earth. Scientists believe that its ancestors evolved towards the end of the third period of the Paleozoic. Despite its modest size, it has many features in common with its other "relatives" , such as beluga and sturgeon. Since ancient times, the meat of the Volga sterlet has been highly valued, and due to overfishing, it is now forbidden to catch them.
Appearance
Sterlet belongs to the group of cartilaginous fish, thus earning the scientific name gannoid. All sturgeons have one thing in common - they have scales that look like bony plates and cover their cylindrical body.
The sterlet is the smallest member of the Acipenseridae family, usually reaching a maximum length of 120 cm and an average size of half a meter with a weight of no more than 2 kg. Its body is slender and elongated with a large triangular head, while the snout is elongated and the lower lip seems to be bifurcated into two sections - due to this feature it is easy to distinguish it from other species of the same family. In addition, she has fringed antennae at the bottom of her snout, which are found on other members of this group.
It has been observed that there are two types of sterlet fish: a sharp-snouted variety, which is classified as a classic species, and a blunt-snouted variety, which has a pronounced roundness at the end of the snout.
The sterlet's head is protected from above by shields that are interconnected, and the body is covered with scales with many tubercles scattered over the surface and similar to grains.The upper fin on the back of the sterlet is located closer to the tail than in other species, and it is also distinguished by the fact that the upper segment of the tail is slightly longer than the lower one.
The classic coloration of this fish species is darker and usually looks grayish brown, along with some pale yellow tints.
There is another variety of sterlet that does not have a bifurcation of the lower lip and boasts a noticeable number (up to 50) of tubercles. Both of these species show similar coloration on the abdomen, but different light shades; sometimes it is even almost white.
It is almost impossible to distinguish between females and males of this fish species, since they have very weak anatomical differences. Both sexes are similar in body size and coloration, and both are covered in roughly the same amount of bony growths.
Lifestyle
Sterlet is a 100% predator that prefers to live in rivers with crystal clear, not muddy water, in a moderate current.Although they may venture into the sea, they tend to stay closer to river outlets. During the summer months, these fish are easily found in the shallow parts of the river, while their juveniles live near estuarine streams or bays.
When winter comes, they migrate to wintering pits, where they remain dormant and do not feed until the ice melts. As soon as spring comes, the sterlet leaves their wintering grounds and swims up the river to breed.
The sturgeon stands out among other sturgeon species with its tendency to live in large groups, even during the winter months when many of its relatives are left alone.
Expert opinionZarechny Maxim ValerievichAgronomist with 12 years of experience. Our best gardening expert.Ask a QuestionHundreds of sterlets can survive the winter by huddling together at the bottom of a hole, which limits their ability to move their fins and gills.Lifespan
This unusual looking fish, no different from other sturgeons, has a long life that can last up to 30 years. However, compared to its relative, the lake sturgeon, which can live up to eight decades, it is short-lived.
The life cycle of fish, like many other species, depends on habitat conditions, food base and other factors. The average lifespan of a fish is about 20-25 years in the wild. At the same time, if the fish lives in favorable conditions created by man (for example, in aquariums), then its life can be extended to 30 years or more with appropriate care and feeding.
Habitat
Sterlet fish is found in abundance in the rivers flowing into the Black Sea, Azov and Caspian waters. It is also found in the northern regions along the Ob and Sev rivers. Dvina.
The habitat of the fish covers the Volga and its tributaries, including the Kama, Oka and other rivers. This type of fish is a typical representative of the Volga fish fauna and is found in the Volga River basin, from its source to the mouth of the Caspian Sea.
In addition, the Volga sterlet is also found in a number of reservoirs and lakes that are connected with the Volga River. For example, it is found in the Kuibyshev, Zhigulevsky and other reservoirs created on the Volga and its tributaries.
In addition, it can be found in Ladoga and Onega lakes. Moreover, people brought it to other water bodies, such as the Neman River, as well as to large reservoirs suitable for sterlet microclimate.
What does a sterlet eat
Sterlet fish is a predatory species that feeds mainly on small crustaceans and worms, as it has a relatively small size. She will feed on both bottom creatures and animals living in the water column, especially with pleasure absorbing the eggs of other fish. Large adults may also prey on and consume smaller fish.
It's exciting to know that male and female sterlet eat differently. This is because females tend to stay near the bottom of the water while males tend to stay higher in the water column. In addition, these fish only hunt at night.
The newly hatched sterlet fry feed on the simplest organisms. As they mature, they gradually begin to consume larger living organisms.
How to breed
Females become sexually mature at seven and a half years, and males reach this stage at four and a half years. Sterlets do not breed annually, but rather once every two years to allow the females to recover from the stressful spawning process. Spawning usually occurs in late spring/early summer when water temperatures reach between 7 and 22 degrees Celsius, with 12-13 degrees being the ideal temperature for spawning of these species.
There are times when spawning starts earlier or later, depending on weather conditions and the amount of water present in springtime.
The Volga sterlet has an unusual spawning pattern compared to other fish species, as individuals living in the upper part of the river tend to breed earlier than those living in the lower reaches.This difference is due to the fact that the spring flood begins first in the upper reaches of the Volga, and then moves downstream. When spawning time comes, these fish prefer places with fast currents and clear water with a hard bottom covered with pebbles. In addition, they are very prolific, as females can lay up to 15,000 eggs at a time.
Sterlet eggs are sticky and take several days to develop into fry that remain in the yolk sac for up to ten days. After the yolk sac disappears, the fry become no more than 1.5 cm in length and bear no resemblance to their adult relatives. The mouth of sterlet fry has a cross-section with antennae, and their lower lip is already divided into two parts, like in an adult. The head is topped with tiny spikes and slightly darker in color than adults, especially around the tail.
After hatching, the fry stay in these areas for a while before migrating downstream when autumn comes and they reach 20 cm. Males and females grow at the same rate and look almost identical; their coloration gives little indication of gender.
It's exciting to know that the sterlet often interbreeds with other members of its family. In the past, when mating beluga and sterlet, a hybrid known as bester was obtained, which was of great value. Since the 1950s, this hybrid has continued to be an object of commercial interest.
The hybrid shows the positive features of both species. Bester has a high growth rate and quickly gains weight, which is typical for beluga. In addition, it reaches maturity faster in terms of reproduction, which speeds up the reproductive process of the species, especially when bred in captivity.
Natural Enemies
The sterlet is generally safe from predators as it usually lives in the deepest parts of the water. However, when they spawn, their eggs and fry are vulnerable and can be eaten for consumption by other fish. Even their own relatives can devour them if they accidentally stumble upon a clutch of eggs.Young sterlet are especially at risk of being eaten by catfish and beluga. In Russia, as well as throughout the world, the main enemy of this fish is man.
Status of this species
Twelve years ago, the sturgeon family showed no warning signs that it would soon be declared vulnerable. This is largely due to the fact that water sources are polluted at an alarming rate, and the sterlet can exist and feed only in clean water. Illegal fishermen, who are not responsible for their actions, further harm the population of this fish. As a result, the sterlet was classified as an endangered species, it is in the Red Book.
Use and value
In the mid-twentieth century, sterlet was traditionally harvested for commercial use because of its abundance. Unfortunately, overfishing caused a rapid decline in the population of this species, which led to the fact that it was forbidden to take it in its natural habitat.Despite this, it can still be found on sale in all known forms, for every taste. So, fresh, frozen, canned, s alted and smoked carcasses are presented. In this regard, the question arises: if they are no longer caught in natural conditions, then where does the sterlet come from?
The bottom line is that the world is populated not only by poachers, but also by individuals who are trying to keep certain species from extinction. This also applies to many other fish species that are endangered. As a result, fish farms have been developed where sterlet can be bred in conditions similar to their natural habitat. This initiative was originally aimed at the description and conservation of the species, but in the end it was possible to return the sterlet as a common commercial fish.
However, this is not easy, because the quality of farmed fish is lower than that of wild-caught fish. However, several recipes for cooking dishes with this type of fish have also been revived.Farm-raised sterlet is not inexpensive, nor are the dishes made from it; however, it allows these endangered species to stay alive, which also applies to other endangered fish species.
Expert opinionZarechny Maxim ValerievichAgronomist with 12 years of experience. Our best gardening expert.Ask a QuestionIt is necessary to know that the sterlet differs from other members of its family not only in its small size, but also in the ability to spawn eggs earlier than other sturgeons.Sterlet is regarded as an undemanding food source, which makes it excellent for hybridization with, for example, bester. Although this species is in danger of extinction, the prospects for its survival are great thanks to individuals who are taking measures to prevent this from happening.
Useful properties
Not only sterlet meat is useful, but its caviar is not inferior in quality to beluga caviar, and the size of eggs is somewhat smaller than that of sturgeon.Containing only 85 kcal per hundred grams of meat, this fish makes it suitable for low-calorie diets. Its meat contains a number of minerals and vitamins, such as zinc, chromium, molybdenum, nickel and PP vitamins.
In addition, it is rich in omega-3 fatty acids, which have a positive effect on brain activity and blood circulation in the eyes. Eating sterlet at least twice a week will help keep your cardiovascular system he althy, thereby reducing the risk of a heart attack.
Researchers have found that eating oily fish is good for the skin, aids vision, and stimulates the central nervous system. Fluoride, an essential nutrient, has been found to strengthen bones and teeth, protecting them from cavities.
Sterlet fish is most often used for making jellies, soups, and also as a filling for pie and pies. In addition, fish can be cooked on a spit. To get a sterlet fillet, it is best to freeze the fish after cutting; this will make it easier to remove the skin and bones.
When cooking with sterlet, remember that prolonged heat treatment kills most of its nutrients. Raw sterlet is considered the most useful; this means that it is worth eating it in s alted or pickled form. It is still useful when consumed boiled, but fried is the least useful and even harmful, as it makes digestion difficult. Therefore, only people who do not know about digestive problems should eat fried sterlet.
The only potential danger associated with eating fish is an individual intolerance to seafood. Also, people with poor pancreatic function should avoid eating fish, as PUFAs (polyunsaturated fatty acids) can worsen their condition.
Boiling the sterlet for about 15 minutes will help retain the most nutrients. The same applies to other types of fish. It is believed that sterlet fish soup is especially tasty when boiled, but it should not be boiled for too long, otherwise it can be overcooked.
Even in tsarist times, when workers on the Volga transported barges along the river, they ate hearty sterlet fish soup to restore strength and vigor.
Unfortunately, this type of fish is no longer so numerous due to human activities. People not only fish it in large quantities, but also pollute water sources; in such conditions it is almost impossible for any fish to survive. As a result, fish populations available for human consumption are getting smaller.
People, of course, do their bit to preserve the species, but this may not be enough. In order to avoid the worst, a significant amount of labor and expense must be put in.
