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Kaluga Sturgeon fish identification, its habitats, characteristics, fishing methods.
There are only two species in genus Huso, which one is famous Beluga Sturgeon living in Black, Azov and Caspian Seas, that’s caviar cost more than $10000/kg. The other one is Kaluga Sturgeon which is one of the biggest of the sturgeon family, the largest fish in entire Amur River basin, they are claimed to be the largest freshwater fish in the world, with a maximum size of at least 2,205 lb (1,000 kg) and 18.6 ft (5.6 m). Like the slightly larger Beluga, it spends part of its life in saltwater.
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The Kaluga (Huso dauricus), also known as the River Beluga is a freshwater fish of the sturgeon family Acipenseridae, belongs to Huso genus, is distributed in the entire Amur river basin from the estuary to its upper reaches, including several large tributaries and lakes, ascending far up to the Argun, Shilka, and Onon including Sea of Okhotsk, Sea of Japan, Ussuri and Sungari in China.
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Four populations are recognized in the Amur River basin: one is found in the estuary and coastal brackish waters of the Sea of Okhotsk, near the northeastern part of the Tatar Strait, and Sea of Japan, near the islands of Hokkaido and Honshu, second is found in the lower Amur, third in the middle Amur, and fourth in the lower reaches of the Zeya and Bureya rivers in the Russian river banks. The estuary population is divided into freshwater and brackish water morphs.
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Description
The Kaluga Sturgeon is a very large fish with a triangular head, covered with several bony plates. It has elongate, fusiform body, covered with 5 rows of bony scutes: dorsal with 10-16 beetles (the first is largest), two laterals (32-46 scutes) and two ventral (8-12 scutes) between rows of small bony scutes grains and rarely more large plate. Dorsal and ventral scutes are larger than the lateral scutes. The mouth is lateral, large and crescent shaped, resides in the entire lower surface of the snout, some part of it moves to the side of the head. In front of the mouth on the underside of the snout there is transverse row of 4 flattened laterally barbels. Inner two barbels are more anterior than outer ones, with about same length. Snout is short and sharply pointed; its length before mouth is shorter than mouth width. Eyes are very small, located immediately behind nostrils at about anterior 1/3 of head.
Caudal peduncle is sub-conical. The upper lobe of caudal fin pointed, covered with rhombic scales, much longer than the lower, rounded. The dorsal fin is shifted toward the tail. Gill membranes free from isthmus and broadly connected with each other.
Distinguish Characteristics
- Dorsal soft rays: 43-57; No Dorsal spines
- Anal soft rays: 26-35; No Anal spines
- Dorsal shields 10-16
- Lateral shields 32-46
- Ventral shields 8-12
- Max length: 18.7 ft (5.6 m)
- Max weight: 2,200 lbs (1,000 kg)
- Max age: 80 years
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Coloration of the Kaluga is dark yellowish green on dorsal side of lateral scutes, yellowish green between lateral and ventral scutes, and light grey-white on the ventral side. Dorsal sides of paired fins yellowish green and ventral sides are white. Dorsal and caudal fins are greenish and anal fin is whitish.
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Habitats
The Kaluga Sturgeon is a benthic (bottom dwelling) species, that inhabit rivers, lakes and coastal sea waters. They are semi-anadromous fishes spend at least part of their life in salt water and return to rivers to breed. The estuary population is represented by two ecological morphs: the freshwater morph and brackish water morph. The freshwater is the predominant and feeds only in fresh water. The brackish water form spends winter in the river or estuary and in late June-early July, migrates to the Tatar Strait and the Sahalin Gulf and in autumn, when the salinity of the estuary increases, it return to the river where they overwinter together with the freshwater form.
In the first year of life, Kaluga consume mostly invertebrates, later switching to juveniles of Chum Salmon and, at age of 3 to 4 years, Kaluga start to feed on adult fishes like saffron cod and ocean perch. Cannibalism is, also, frequent. During winter and during spawning migrations, Kaluga does not feed at all.
Spawning
In autumn and early winter, most of the mature fish migrate from the estuary into the Amur River, where they spend the winter in preparation for spawning during the next spring. Adults do not spawn every year but at least every other year. With increasing age, the spawning interval increases to three, four and more years. Males spawn less often, once every 3 to 4 years, and females, every 4 to 5 years. Males first mature at ages of 14-21 years of age, and females at 14-23.
Spawning occurs May-July at water temperatures of 54-68°F (12-20°C) with the peak of spawning in the middle of June. The Kaluga Sturgeon spawns in lower reaches of the main river bed in strong-current habitats in the main stream of the river on gravel or sandy-gravel bottom at depths of 3 to 7 meters. Females carry an average of 41,400 eggs per kg of body weight. After spawning, the fish return to the estuary to feed. Fry are carried downstream in the current.
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Kaluga 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, second after Beluga caviar, but meat also is sold fresh, smoked and frozen; eaten broiled, boiled, fried and baked.
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