Beluga sturgeon | European Tracking Network

Beluga sturgeon

Huso huso

Species description and statusVery big, heavily build fish with spindle-shaped body. Large individuals often appear humpbacked. The rostrum is conical with numerous sensory pits on both ventral and dorsal surfaces. Possess two pairs of barbells in front of the mouth, which are long and laterally compressed with foliate appendages. Very big ventrally situated mouth which can projects forward. Upper lip continuous while lower lip is interrupted by large gap. Skin surface covered by five horizontal rows of scutes. On adults, scutes undergo absorption. It may reach a maximum size of about 1300 kg and more than 6 m in length (Balon 1967). The color of adult specimens is gray, blue gray or dark brown with silver or gray lateral surface. The species is distributed in the Black, Azov and Caspian seas but nowadays widespread construction of hydroelectric dams has greatly diminished the species’ range in the past century. Historically, the Danube supported one of the largest known beluga spawning migrations (Balon 1967), however, construction of the Iron Gate Dams in 1970–1984 blocked upstream access to the middle and upper Danube. Similar habitat loss has occurred on most other major beluga rivers including the Dnieper, Don, Kuban and Volga.

Nowadays the populations in the Caspian and Azov Sea are nearly extirpated. In Black Sea the species is also rare, but recent surveys of juvenile abundance confirm that belugas are still reproducing in the Lower Danube. The uninterrupted spawning habitat of the species is about 850 km. The species is included in Appendix II of CITES and it is categorized as Critically Endangered by IUCN with decreasing population trend.

Figure 1. Distribution of Beluga (Huso huso) taken from

Knowledge gaps: Migration routes, periods of migration and the distribution in marine and transitional waters are not well known. The effect of hydropower dam construction on the movements and reproduction success is also poorly understood. Tagging studies show that there are still reproducing populations in Lower Danube, but data are still not sufficient to give information about the spatial and temporal scales. Spawning grounds are still very poorly investigated. Few sites are known in Romanian stretch of the river, but still no data about spawning sites in Bulgarian part. More information on the Black Sea movements and distribution, as well as on the wintering sites is required. 

Regions of interest: The regions of biggest interest are Lower Danube and Black Sea.

Telemetry tools: Acoustic telemetry with data loggers are the most used tools for characterizing the movement patterns in Danube River. Telemetry methods should be also used to research beluga movements and behavior in the transitional, coastal and marine waters of the Black Sea. Tagging of juvenile specimens by PIT-tags is also a possibility for surveying their biology and migration.

Benefits within the ETNUsing the ETN to further characterize beluga migration and behaviour in Lower Danube and Black Sea would greatly enhance our ability to better manage this critically endangered species. This is a common territory of few countries so joint research efforts, sharing of infrastructure and international collaborations are required. In addition, ETN would give additional insights in the location of the spawning grounds and environmental preferences of the species.

Contacts: Tihomir Stefanov (


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