Sakhalin sturgeon (lat. Acipenser Medirostris) transitional type of fish. It grows up to 2 meters, weighing 60 kg. Distributed in the northwestern part of the Pacific Ocean, in the waters of the Japanese and Okhotsk seas. In Eurasia, it is found on Sakhalin and in Primorye (in the Gulf of Peter the Great, in the rivers of the Sea of Japan). Some individuals prefer the mouth of the Amur River.
Description and appearance
Sakhalin sturgeon in size does not differ from other representatives of the species. The average weight of fish is 30-35 kilograms, length about 1.5 meters. Like all representatives of this kind, the elongated body shape is inherent in the Sakhalin sturgeon. The head is large, pointed.
Along the torso, the membranes of the gills are attached to the interdental gap, while not a single free fold is formed. Lower lip is divided in half. Thin fringe is located on the antennae, closer to the fish mouth. The body between the dorsal and lateral beetles is covered with stelled bone plates, sometimes located under the side beetles of the right rows plates and granules.
Reproduction
For playback, he rushes into rapid river flows, from where he continues to migrate further. Propagation occurs from June to July, in the Tumin River, at a water temperature of 12-24 ° C.
The sturgeon is propagated not annually: in males, the reproductive period begins only at 4 years old, in females at 5 years old. Propagated in the channel of the river on gravel-sand or rocky soils. The fertility of adult females exceeds hundreds of thousands of eggs. Eggs of a very large size, reach the volume of caviar of the beluga. Young individuals live in fresh water for the first 4-5 years, leading a sedentary lifestyle at the bottom, which prevents their premature descent in the sea. Adolescence occurs with a length of 1 m and weight of 8-10 kg, in males-at 10 years, in females-2-3 years later.
Propagation begins in the summer, when the Sakhalin sturgeon goes to sea. Young sturgeons live in the river up to 4 years. Having reached the masses of 8 kg, males ripen. In females, the process is slightly drawn, having gained about 11 kg of females become sexually mature.
Habitat
Sakhalin sturgeon lives in sea water, preferring to the life of the Water of the Okhotsk and Japanese Sea. For spawning, individuals rush into the rivers. Among them are the Sukhan, Toppi, Tump and other rivers among them. In addition, sturgeons are active in Japan on the Ishikari River.
On the territory of Eurasia, the species is distributed in the Terter Strait and in separate rivers flowing into it these include the territory of the Khabarovsk and the Sakhalin Region. Currently, only one river is reliably known Tumin, where its natural reproduction has been preserved.
Reproduction on the Vyakhta River in the Sakhalin Region is characterized by a limited scale. Until today, this zone included all coastal areas around the island of Sakhalin and sea waters near the coast of the Primorsky Territory.
Lives in the northern part of the Pacific: along the coast of the United States from Monterrey (USA, California) to the Columbia River. Sakhalin sturgeon can be found along the Asian coast from the island of Hokkaido and the Korean Peninsula (Vonsan) to the mouth of the Amur River. As well as in the Tym River and the Gulf of Aniva, off the northwestern coast of Sakhalin and in the Olyutor Bay of the Bering Sea.
The habitat is typical for passing fish. Young individuals live in mouths and coastal areas, and adults live in the sea. For propagation, he enters small rivers with a quick flow, along which it rises further deep along the mouth.
Reducing the population
The extinction of such a subspecies as oak felt oxytropis lanuginosa.
The current number of adults in Russian waters can be estimated at several hundred people (no more than 1000-1500 people). In the 60s and 70s, their population decreased markedly due to the strong economic growth of the Tatar Strait.
The main reason for the disappearance is poaching, illegal fishing. In addition to pollution of spawning rivers of oil production and precious metals, there are negative consequences of logging, illegal catch of young individuals in the lower reaches.
Safety
Fish as an endangered view is listed in the “Red Book”. Currently, experimental work on artificial reproduction is underway and two artificial basins have been created on about. Sakhalin. Work began on the creation of a cryoconsense sturgeon genome.
The state continues to actively contribute to the preservation of natural reproduction and develops various programs to support and recreate the species, both in artificial and natural conditions of existence.
Lifestyle
The fish tries to spend most of his life directly into the sea and remains in deep waters. Begins to multiply at the age of at least 10 years, with the frequency of reproduction once every five years. The female sturgeon lays up to one hundred thousand large eggs. For propagation, the fish enters small rivers at a distance of about 30 km, and then the individuals returns to the sea. Larvae did not appear before the 11th day and immediately hide under the stones. This feature of behavior is due to the fact that young sturgeon becomes a favorite prey and a delicacy for many predators.
