The Russian sturgeon matures slowly; males typically do not reproduce until they are between 8 and 13 years old, and then do so every 2 to 3 years. Females are not sexually mature until between 10 and 16 years of age, and only reproduce every 4 to 6 years (1). Individuals of up to 48 years old have been recorded; however, the typical life expectancy is around 38 years, and even this may be somewhat optimistic (2).
Spawning takes place between April and June, when the waters are warm enough. There are two distinct forms of this fish, based on their migratory habits. One type is anadromous, migrating up river from the sea to spawn. The larvae of anadromous fish then drift downstream with the flow of the river, and juveniles spend their first summer in the sea, where they remain until fully mature. The second form of the Russian sturgeon is now considered to be extinct, but was an entirely freshwater variety that did not migrate, and was found in the Volga, Danube, and Ural rivers (7).
Within the anadromous form, both autumn and spring migration runs occur, so yet another distinction can be made based on these migratory patterns. Individuals that migrate upstream in spring spawn in the lower levels of the river, whereas those that migrate during autumn spend the winter in freshwater, spawning further upstream during the following spring (1).
The Russian sturgeon feeds on a wide range of organisms, including crustaceans, molluscs and small fish (1).