Sterletus nudiventris (Lovetsky, 1828)

Freyhof, JÖrg, Yoğurtçuoğlu, Baran, Jouladeh-Roudbar, Arash & Kaya, Cüneyt, 2025, Handbook of Freshwater Fishes of West Asia, De Gruyter : 53

Sterletus nudiventris

Common name. Ship sturgeon

Diagnosis. Distinguished from other species of Acipenser and Sterletus in West Asia by: ● lower lip continuous, not interrupted in middle / ● first dorsal scute larger than following ones, fused with head, forming an obtuse angle with head profile / ○ barbels fimbriate / ○ 24–45 gill rakers / ○ 11–17 dorsal scutes / ○ 49–74 lateral scutes / ○ diploid. Size up to 2200 mm TL.

Distribution. Black, Azov, Caspian, and Aral Sea basins. Danube up to Bratislava, Volga up to Kazan, Ural up to Chkalov, unknown or very rare in others. Introduced in Lake Balkhash ( Kazakhstan) from Syr-Darya (Aral basin) in 1960s.

Habitat. At sea, near coasts and estuaries. In freshwater, deep sections of large rivers. Juveniles in shallow river habitats. Spawns in strong-current habitats in mainstem of large and deep rivers on stony or gravelly bottoms.

Biology. Anadromous, with some non-migratory freshwater populations. Males first spawn at 6–15 years, females at 12–22 years. Recorded life span of 36 years, but probably

Sterletus persicus ; aquaculture, Iran; ~ 550 mm TL.

much longer. Spring and autumn migrations occur in most drainages.Individuals migrating in autumn remain in river until following spring to spawn. Females spawn every 2–3 years and males every 1–2 years in March–May and at temperatures above 10°C. Most juveniles migrate to sea in their first summer and remain there until maturity. Recorded migrating 1500 km upstream in Amu Darya. Some individuals stay in freshwater for longer periods. Feeds on a wide variety of benthic fish, molluscs and crustaceans.

Conservation status. CR; survival appears to depend on stocking. Extirpated from Aral and Black Sea basins. Only occasional records from Danube, Rioni, and lower Volga. Only a very small population may remain in Ural ( Russia, Kazakhstan). No natural spawning in Iran. Established in Lake Balkhash, where it forms a small population, but details are not known. Caspian S. stellatus introduced in Aral basin were infected by parasitic monogenean flatworm Nitzschia sturionis , which caused collapse of Aral population of S. nudiventris .

Further reading. Sokolov & Vasil’ev 1989a (biology).