Atlantic sturgeon - Acipenser sturio

Atlantic sturgeon can reach length of 5.5-6 m and a weight of 1,000 kg. The body is elongated and low, the snout is pointed and slightly turned up. Dorsal scutes range from 9 to 16, lateral scutes 24-39 and ventral scutes 9-14. Between the dorsal and lateral scale rows, there are many patches of rhombic denticles. The first ray of the pectoral fin is transformed into a strong spine. The snout is broad, but more pointed than in A. gueldenstaedti. The lower lip is distinctly interrupted.

This species is confined to the Northeastern Atlantic Ocean, especially to the shallow parts of the North and Baltic Seas and some coastal water bodies in the Mediterranean and Pontic region, including the Ligurian, Tyrrhenian, Adriatic, Ionian, North-Aegean, Marmara and Black Seas. In the Black Sea watershed, sturgeons ascended into the Danube Estuary, the Inguri, the Rioni, the Yesil Irmak and the Kizil Irmak. Today the Atlantic or Baltic sturgeon is close to extinction. It is believed to be extinct today in the Lower Danube .

During its stay in the sea it is a littoral species, limited mainly to estuaries with muddy bottoms. Younger specimens usually stay within a radius of more than 100 km of the river mouth, and in the sea, the majority are caught at depths of 20 to 50 m.

(www.fishbase.org)

The maximum documented age is 48 years. Specimens become sexually mature at an age of 7-9 years. The first spawning of females occurs one to five years later than that of the males. The males are able to spawn annually, while there is a one year interval between each spawning of the females. The spawning period is reported to continue from March to August, at water temperatures of 7.7 to 22 ºC. They spawn at depths of 2-10 m over a rocky or pebble bottom with swift currents, either in the main channel or in lotic branches. Atlantic sturgeons enter the rivers from January to October, and the peak migration usually occurs from the beginning of April to the end of May, during periods of high water. Existence of a weak late summer and autumn migration suggests that there is a winter race of A. sturio, analogous to those of other diadromous sturgeon species.

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

Adult A. sturio feed on benthic invertebrates, such as Molluscs, Polychaete worms, Isopods and shrimps, as well as on small fishes, including sand eels (Ammodytes) and Gobiids. In the Black Sea, however, adult sturgeons feed mainly on fishes, and almost exclusively on the European anchovy (Engraulis encrasicholus). Adults usually do not eat during migration and spawning.

There is a permanent ban established for the Atlantic sturgeon catch (“Official Gazette of the Republic of Serbia”, No 36/09) and the I level of protection (“Official Gazette of Republic Serbia“, No 50/93).

Source: Reinartz, R. (2002). Sturgeons in the Danube River; biology, status, conservation. International Association for Danube Research (IAD), p. 150.

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