Kaluga (lat. Huso Dauricus) or tramplement, genus Belug, sturgeon family.
Description
Kaluga is an amazing fish, which has long been listed in the International Red Book, since it belongs to the types of freshwater fish rare today. It was Kaluga in the past that possessed valuable commercial qualities (first of all we are talking about her caviar).
Not so long ago it was believed that this type of fish is extremely freshwater, but there was evidence that some young individuals of this species have mastered a fairly extensive marine area of the Sea of Okhotsk (its northern regions).
This fish is very often confused with Beluga, however, the main difference between Kaluga and Beluga (and its main identifying sign) is the number of rays in the spinal fin area: unlike Beluga, this fish has less than 60 (usually about 57).
Kaluga habitually lives in a moderate belt, settling in the area of the Amur River basin, preferring places up to 50 meters deep.
Appearance
Kaluga dimensions can be hit: sometimes adults reach sizes up to 5.5 meters (the maximum registered length of Kaluga is 560 cm), and its weight sometimes exceeds a crazy number in one ton. The fish reaches puberty at a respectable age about 16 years at the moment when its weight reaches serious 400 kg, and the length begins to exceed two meters.
The muzzle, or, as is commonly called in fish, snout, kaluga is quite characteristic of this family: slightly pointed, with a conical shape, flattened from the sides, and not as long as that of sturgeon. Kaluga’s mouth is large in size, and in its shape resembles a crescent: it occupies the entire lower part of the snout, reaching the very head, ending with an intermittent lower lip. And its edges are crowned by compressed mustache, devoid of leafshaped appendages.
Under the interjacket gap, Kaluga has a free fold, which is formed by the fused gill membranes.
The color of the fish is most often greenish-gray, and the belly is a lighter tone; In addition to the spinal bugs (the first of which is the most noticeable), the body of Kaluga is covered with bone grains, which are sometimes transformed into large rounded plates.
How much lives
The age of reproduction in this fish occurs no earlier than 16-17 years, when Kaluga reaches the corresponding size. In full force, the fish enters only by 22 years.
Biologists distinguish between several types of this fish:
This longliver among fish is able to reach the age of up to 55 years, while gaining a length of up to 6 meters and weight exceeding 1200 kg.
In this case, the usual fishing size of Kaluga ranges in the region of 150 kilograms.
Where it lives
Kaluga does not live at all in the river reservoirs of the city of the same name, as one might think, based on the name, but exclusively in one area in the basin of the Amur River. And spawning of the entire population of this fish takes place exclusively in the Amur estuary.
To date, due to the exceeded commercial demand for the caviar of this fish, Kalug has almost disappeared from most of the usual habitats in the desalinated areas and rivers of the Amur basin, where it was recently quite common.
Kaluga occupies the territory of the Amur basin, sometimes found in the rivers Argun and Shilka, and from the Sungari and Ussuri river it disappeared almost completely due to the fishing of the Chinese. Single finds of migrating young individuals are sometimes found in the coastal waters of the North Okhotsk Sea (Kamchatka, Hokkaido and Sakhalin).
What eats
Kaluga is a typical predator, and at an early age feeds on small brothers or other small invertebrates (mosquitoes and shadows larvae, various types of shrimp).
Individuals in more adulthood (from year to year and older) consume large individuals of river fish (sandcar and chebak, carp, thick-rod, white Amur): and the most attractive for them are more often salmon. During spawning and passage, this is usually precisely salmon, but Kaluga does not refuse herring, smelt and a sig.
In the Amur Liman, which is the main full area of Kaluga’s habitat and spawning, the main food of these fish usually becomes pink salmon or keta, and since the total population of almost all commercial fish has decreased significantly, today there are also quite known cases of cannibalism. Moreover, in winter, the fish does not stop eating.
In Kaluga, all her physique is adapted for hunting her mouth is even arranged in the form of a pipe in which the fish literally sucks its victim with water. Since the dimensions of this fish require significant feeding, it does not suffer from the lack of appetite: for example, Kaluga three meters can swallow a fish in size about a meter, and its stomach is able to accommodate up to a dozen victims of such volumes. Such an appetite allows you to achieve such amazing sizes.
Reproduction
If we talk about the fertility of Kaluga, then it is able to postpone over four million eggs (usually the average indicator is the figure of 1.5 million). Not so long ago, Kaluga’s spawning spawning was scattered from the spike to the Tyr River, but now, as Chinese biologists say, sexually mature Kaluga is not able to rise above Blagoveshchensk.
The process of spawning itself, as a rule, takes place at the end of spring at the beginning of summer, and usually a platform for it is pebble or sandy soil. Usually between the spawning (first and subsequent) passes for at least four years, and with age this period only increases. It is interesting that the mass of the calf can be at least a quarter of the total weight of the body of the fish.
Kaluga caviar is a bottom type of caviar, which is glued to the substrate, about 4 mm in size. The embryo matches for about 108 hours (if we are talking about a temperature of about 18 degrees), or for approximately 16 days, if the water temperature is about 10 degrees. The length of the hatched embryos is approximately 12 mm, and they switch to a mixed type of power, only reaching a length of 20 mm. This usually happens after 8 days (at a water temperature of about 21 degrees), or after 16 days, if the temperature is about 15 degrees.
By autumn, the fry reach a length of about 30 cm and weigh almost 100 grams. And by the age of oneyearold age, Kalug reaches 43 cm long and weighs almost 150 grams. On the territory of the estuary, and in the lower regions of the Amur, the fish grows significantly faster, and most of its females are capable of breeding at the age of 20 years, reaching 230 cm long and masses more than 100 kg (Kaluga’s males have slightly more modest parameters). Among the immature individuals, the ratio of floors is approximately equal, but in adult fish, females, which make up about 70% of the population, significantly predominate.
Natural enemies
Since Kaluga has significant natural dimensions, and even a predator, she does not have serious enemies in nature. Of course, the exception is the human factor, since Kaluga is a valuable commercial fish that has very delicate and tasty meat and no less valuable caviar. All these qualities made Kaluga an object of fishing fishing on an illegal scale.
Poachers engage in illegal catch of this type of fish, preferring immature individuals that have not reached a mass of over 20 kg and this naturally affects the size of the Kaluga population. Such activity significantly reduces the number of fish (ten times), and its spawning course is violated. It was these factors that served as the basis for entering this type of fish in the International Red Book. To restore the number, it is necessary to completely stop the capture of the population, and provide the necessary conditions for artificial propagation.
Population and status of the species
Today, Kaluga is an endangered species of fish, since its population has several tens of thousands of sexually mature individuals (about 50 thousand): individuals from 15 years, weighing more than 50 kilograms and a long body of about two meters, were taken into account. In recent years, they have been characterized by a significant decrease in the number of this type: this is primarily due to the fishing activity of a person. With the continuation of such a trend by the end of the decade, the size of the fish population will decrease by ten times.
If we talk about accurate data about the population of this fish today, then they are absent: the red book of our country indicates the figure of approximately 2 thousand sexually mature individuals that have reached the age of two years. The population continues its reduction, and in connection with an increase in the level of environmental pollution (Amur), and due to the non-limited activity of fishermen (both Russian and Chinese). In our country, the fishing of this fish has been banned since 1958, but in China, sturgeons are completely legalized at the state level.
In Eurasia, Kaluga is protected at the state level: it is listed in the Red Book of Eurasia and in the International Red Book. For many years now, in Eurasia, a ban on the fishing of this type of fish has been operating: in 1991, the regulated fishing was partially resumed, and after ten years it was prohibited in full. The exception is the control catch, which is carried out by the Pacific Research Fisheries Center, its Khabarovsk branch.
Code for research purposes is made on the territory of the Amur basin and its estuary with a volume of about 14 tons, but the amount of illegal turnover and catch is, according to experts, about a few hundred tons.
Despite the long ban on catching and the periodic production of young animals, due to poachers and environmental pollution, the Kaluga population has not been restored, but, starting in 2004, on the contrary, a persistent decrease in its number has been observed.
And at the moment, the main method of maintaining the population of this disappearing species is artificial reproduction along with the release of young animals.
Young animals of this species traditionally are walking in the area of the Amur estuary, less often in the Tatar Strait. The problem is that the local population of the islands and the mainland still carries out the capture of this redBook type with the use of shift networks.
Economic significance
Fish from the sturgeon family, to which Kaluga belongs, are valuable species in the vast majority of parameters, the main of which is the caviar of these fish. It is it that is characterized by high nutritional value, a large amount of beneficial substances (iodine, fatty acids, minerals), which makes this product industrially attractive.
And the special composition of the skeleton of Kaluga allows you to use almost 85% of the body of this fish for cooking dishes. Moreover, weight loss due to the heat treatment process, as well as the amount of adipose tissue, make Kalugu the most preferable fish product. And these factors caused mass capture in a significant scale of this type of fish.
At the end of the 19th century, the maximum catch of this fish was 600 tons, and in the middle of the last century this figure was already 200 tons. Chinese fishermen hunt Kaluga using largeearned networks called ahana, and the tackle, which was used until the middle of the last century hook tackle is prohibited. Sometimes Kaluga may come across as a clock at the time of capture of passing salmon and partial with smooth gear. Both caviar and fish meat that were grown in pond farms are distributed in China and export.
