Other attributes
Spiracle present. Snout and caudal peduncle subconical. Gill membranes joined to isthmus. Mouth transverse and lower lip with a split in the middle. The barbels are either smooth or slightly fimbriate. The length of the snout is highly variable (33.3-61 per cent head length). 20-49 gill rakers fan-like, each terminated by several tubercles. Dorsal: 30-56 fin rays, anal: 17-33 fin rays. 10-12 dorsal scutes; 32-62 lateral scutes; 7-16 (20) ventral scutes. The scutes of young specimens are sharply tipped, but no in adult ones. Numerous small bony plates are scattered between the rows of scutes. There is a great variability in the colouration: from light grey to a dark brown on back and sides, and from white to yellowish on the underside.
Spread
It is most present in all of the major Siberian river basins that drain northward into the Kara, Laptev and East Siberian Seas, including the Ob, Yenisei (which drains Lake Baikal via the Angara River) Lena, and Kolyma Rivers. It is also found in Kazakhstan and China in the Irtysh River, a major tributary of the Ob.
Production cycle
Production cycle of Siberian sturgeon
Seed supply
Males and females are kept separately, because of the different products that are sold from sturgeon rearing. The absence of sexual dimorphism led to the development of several methods of sexing immature fish: biopsy and observations, dosage using plasmatic 11-ketotesterone, and ultrasound scans. This is normally carried out at about 3 years. The males are then sold. The females are kept and grown on for several years until they are mature enough to produce caviar. They are then harvested for meat. Some may be kept for broodstock, for future reproduction.
Hatchery
The fertilised eggs must undergo an anti-adhesive treatment to prevent them clumping together during incubation. Treatment in an aqueous clay suspension is very often carried out, and sometimes milk is used. After rinsing, the eggs are placed in incubators, usually Zoug jars or McDonald jars.
Embryonic development takes place in about 6 days at between 13 to 14°C. Normal larvae can then be easily selected, because of their positive phototropism.
