Starry Sturgeon
Stellate Sturgeon
Acipenser stellatus Pallas, 1771
Order Acipenseriformes
Family Acipenseridae
Conservation status: in Bulgaria: Critically endangered CR [A1ad], BDA-II, IV; International: IUCN [EN A2d], BeC-III, CITES-II, HD-V.
General distribution. The Caspian Sea, the Sea of Azov, the Black Sea and the Aegean Sea, as well as the rivers that empty into them. The largest population is found in the Caspian Sea, where the species enters the rivers Volga, Ural, Terek, Kura, etc., for spawning. In the Sea of Azov, it migrates into the rivers Don and Kuban. In the Black Sea, it enters the Danube River and its tributaries Sava, Drava, Prut, etc. In the Aegean Sea, single individuals enter the rivers Struma and Maritsa.
Distribution and abundance in Bulgaria. In the past, it was a common species in the Bulgarian waters of the Black Sea and the Danube River [1, 2, 3]. It was also recorded, though rarely, in the Maritsa River [1, 2]. Over recent years, its abundance has declined considerably [4]. In the 2002-2005 period alone, its annual catch in the Danube River and the Black Sea decreased around 3-fold [5].
Habitats. During the reproduction period, it is found in permanent large rivers, and during the rest of the period – in open sea, coastal areas and estuaries.
Biology. The males reach sexual maturity at the age of 5–9 years and females at 10–13 years [6]. Spawning lasts from April through September, in deep water with strong current and sandy and gravel bottom [3, 7]. The fecundity varies between 700 000 and 2 120 000 eggs. Juveniles feed on insect larvae, and adults – on mollusks, crustaceans and fish [1, 3].
Similar species: In the Bulgarian section of the Danube River and the Black Sea, another 5 species of sturgeons have been reported: the beluga (Huso huso), the Russian sturgeon (Acipenser gueldenstaedtii), the ship sturgeon (A. nudiventris), the sterlet (A. ruthenus) and the common sturgeon (A. sturio). The starry sturgeon differs by its long sword-like snout and lower number of lateral scutes (26–43).
Negative factors. Loss (degradation) of spawning grounds, as a result of river regulation by dams and weirs; water pollution; poaching and overfishing.
Conservation measures taken. The species was included in the Red Book of the Black Sea (1999) and in Annexes II and IV of the Biological Diversity Act (2002). An Action Plan for the Conservation of Sturgeons in Bulgaria has been adopted (Ministry of Environment and Water, 2004). A temporary ban on catch of sturgeons in the Black Sea was initiated (Ministry of Agriculture and Forestry, 2006).
Conservation measures needed. Imposition of a total ban on sturgeon fishery. Reintroduction of the species into the Danube River.
References. 1. Kovatcheff, 1923; 2. Drensky, 1951; 3. Stojanov et al., 1963; 4. Vassilev, Pehlivanov, 2003; 5. Ministry of Agriculture and Forestry, 2002-2005; 6. Shubina et al., 1989; 7. Svetovidov, 1964.
Authors: Yanaki Sivkov, Tihomir Stefanov, Teodora Trichkova
