Sterlet - Acipenser ruthenus

Sterlet reaches length of 125 cm, and weight of 16 kg. It represents the smallest sturgeon species in Danube River. There are 11-18 dorsal scutes, 56-71 lateral scutes, and 10-20 ventral scutes. Sterler differs from ship sturgeon by lower lip, which is interrupted in its center, and sterlet also differs from other sturgeon species by fimbriate barbels and larger number of lateral scutes. Length of rostrum varies and it is usually 37-49 % of total head length.

Sterlet is exclusively potamodromous species, and it inhabits river areas in lowlands. It is Eurasian species and it inhabits rivers which belong to Caspian, Black, Azov, Baltic and Artic Sea basins. Sterlet used to be present in Danube River as far as Ulm and Regensburg. Sterlet usually dwells in mainstream of river flow, in deeper depressions of river bottom, above stone, gravelly or sandy bottom. During spring rise of water level, sterlet goes to flood areas because of food. In winter it stays still in groups, in depresions of river botom.

(www.fishbase.org)

Maximal recorded age was 26 years. Males become sexually mature at the age of 3 - 5 years and females at 4 - 7 years. It is believed that younger individuals are spawning each year, and the old individuals every second year. In Danube River spawning is in April and May, during high water level, on temperature of 8-19 ºC, on depth up to 10 m. Sterlet is spawning on gravelly ground with fast river flow, on the river bottom as well as in flood areas during spring floods. Although sterlet is residual species, during spring floods it swims upstream for spawning.

Fall of sterlet catch

Basic food of sterlet are different benthic organisms, most significant of them are insect larvae, mainly Chironomidae, Trichoptera, Ephemeroptera and Simuliidae. It feeds also with larva of Plecoptera and Heleidae, small mollusks of genera Sphaerium, Pisidium and Viviparus, and representatives of Oligochaeta, Polychaeta, Hirudinea and other benthic invertebrates. During spawning period of different fish species, significant part of sterlet diet are eggs of those species.

Sterlet range; green area - present, red area - extinct (www.cites.org)

Temporary ban on sterlet catch, is determined for period from 1st of April until 31st of May, while minimal length for catch is 30 cm (“Official Gazette of Republic Serbia“, No 100/2003).

Taken from: Lenhardt, M., Hegediš, A. and Jaric, I. (2005). Action plan for sturgeon species management in fishery waters of Republic Serbia. Institute for Biological Research “Siniša Stankovic”, p. 21. Developed for Ministry of Science and Environmental Protection of Republic Serbia.

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