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Sterlet Sturgeon fish identification, its habitats, characteristics, fishing methods.
The sterlet (Acipenser ruthenus) is a common Eurasian freshwater species of sturgeon found in almost all rivers in European Russia and Siberia, and an angling species all over the world, one of the smaller species of sturgeon. The Sterlet suited for keeping in garden ponds as its slower growing and has a smaller maximum size than other species available. The name Sterlet refers to the small bony stars (Scutes) found in the skin.
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The sterlet (Acipenser ruthenus), is a true sturgeon of family Acipenseridae, widely distributed in the rivers basin of the Black, Azov and Caspian seas, in the basins of Northern Dvina, Ob, Yenisei and Pyasina, penetrated into the basin of the Ladoga and Onega lakes. They inhabit rivers basin of the Neman, Western Dvina, Onega, Pechora, Cupid and Oka.
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Description
The true Sterlet (Acipenser ruthenus) can be identified by the white fin edges and lateral scutes. From all other kinds of sturgeon Sterlet easily distinguished by its small size and its extra-long pointed narrow snout. They have four long, fringed barbels, reaching to the mouth, the lower lip clearly split into two parts and contiguous lateral bony plates, called scutes. The Sterlet has five longitudinal rows of scutes, located in 5 series, one of which located the middle of the back (11-18 dorsal), the two extend laterally drawn on the sides (56-71 lateral) and two on the edges of the belly (10-20 ventral). Between the scutes the skin remains naked or covered with small bony scutes different shapes. In addition, Sterlet, not like other sturgeons, has dorsal bony plates closely located to each other, numbering 13-17, and every dorsal scute ends up with a rather sharp spine behind.
Distinguish Characteristics
- Dorsal spines: 13
- Dorsal soft fin rays: 28-54
- Anal spines: 9
- Anal soft fin rays: 14-34
- Dorsal scutes: 11-18
- Lateral scutes: 56-71 (usually 60-70)
- Ventral scutes: 10-20 (usually 13-15)
- Max length: 125 cm
- Max weight: 16.0 kg
- Max age: 20 years
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The Sterlet is quite variable in coloration, depending on the habitat, but usually has a yellowish ventral side. Dark-brown to grey, sometimes dark green tint on the back, yellowish-white belly, fins are gray with ventrally yellowish-white edges. The scutical lines are visible running down the body. Back and flanks are beige. Ventral’s and lateral’s scutes are very light-colored, nearly white. Also Albino Sterlets can be found with a pale yellow, almost orange body and orange to yellow eyes.
They can grow to around 1 meter after 10-12 years and attain a maximum of around 1.2m and 16kg, rarely exceeding a length of 3 ft. The average length does not exceed 53 cm and 1-2 kg of weight. Like most fish species, they growing very quickly during first years, but as soon as reached sexual maturity, they have been growing in thickness more then in length, so that only the weight is increases in proportion to the age. Although weight depends and changing during the year: before the spawning sterlet weighs much more than after it, and then during the summer the weight increases again. At the beginning of the autumn starlet can lose even half of its original weight. The length of the snout can be variable, from sharp-nosed sterlet to blunt sterlet. Sharp-nosed starlet known as running, which is constantly moving from place to place and blunt is the stagnant stick to a particular locality this why it is bigger, wider and more yellow color.
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Habitats
The Sterlet is a freshwater species that only rarely is found in brackish water and mostly inhabits rivers and their tributaries. They occur in large rivers, usually in the current and in deep water. More sedentary than some of the other species the Sterlet tends to spend day times down in the deepest parts of the pond, constantly at the bottom, hidden places, becoming more active as dusk approaches, in the evenings or at night, when it moves to flooded areas to feed. It is often seen looking for food around the edges of shelves and drop-offs. Like other sturgeons, it aggregates in bottom holes in winter and exhibits very little activity. In spring, when ice breaks, it rises from the bottom holes and moves upstream for spawning.
The sterlet's main source of food is benthic organisms; they commonly feed on crustaceans, mollusks, worms, and insect larvae. Zooplankton and fish eggs are part of the diet if available. Sterlet often turns over belly up and catches with their mouth falling into the water insects, especially the broom during fall.
Spawning
Among other sturgeon Sterlet is distinguished by the early sexual maturity: Males first spawn at the age of 4-5 years, females - 7-8 years. Apparently, the males always have a relatively smaller size and weight than females. They spawn in mid-April to end of May. The entire spawning lasts for about two weeks. Usually Sterlet spawns in the river channel, but there are some indications that the sturgeon spawning and sometimes in flood plains, resulting in deep ruts and erosion gully in which the water flows down the hollow sometimes even at a higher rate than in the river. The main spawning grounds for sturgeon - not flood-plain meadows and rocky ridges, like underwater hills, formed of boulders and gravel, generally deep and fleeting space of the bed, covered with coarse sand, cartilage, gravel or stones, many eggs are attached here as fish tightly that they can not wash away with even the most powerful water current. The speed of flow is a necessary condition, since otherwise the eggs were buried to mud. The depth of these spawning grounds is 6-20 m.
Female lie an eggs and after that males pour milk, presumably, they are exempt from the sexual products rather by friction on the rocks. Fertility depends on length and weight. A female may lie from 4,000 to 140,000 eggs. Right after spawning adults migrate to deeper parts of rivers, where they spent the winter in an inactive state, not feeding. Regulation of rivers usually improves feeding sturgeon, but worsens the conditions of its reproduction. It feeds mainly on benthic invertebrates, fish eggs. After spawning sturgeon reproductive organs occupy a very small space, and a new type of caviar is initially very small whitish seeds. The new eggs almost reached its normal size after 2-3 weeks, having brownish-gray color, and in short, become nearly mature eggs, which turn black in autumn and is illuminate through the abdominal integument in the form of a thin cavity.
The eggs are very adhesive; they have a rectangle shape and shady color, fairly smaller than the other sturgeons. They deposited on the stone-pebble soil. The color of eggs is consistent with the color of sturgeon’s eggs, and the darker the last, less exhausted, the better developed. Larvae hatch very quickly, after 4-5 days. During their first summer fry Sterlet stay in the river environment at first 2-3 month and after at approximately 18-24 cm length they move out above the rocky ridges to feed in the evening, and move upstream only late autumn. They grow fast, in the fall sterlet are over 4 cm in size, in the year they reach 9-13 cm, in two years they are 18-22 cm in length, before spawning in the 3rd spring they are 27 to 30 cm in length.
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Sterlet caught with seines, mostly smooth with large networks wholes; main fishing of this fish is on the high seas. Fisheries are based almost entirely on the value of the caviar, but meat also is sold fresh, smoked and frozen; eaten broiled, boiled, fried and baked.
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