European regional assessment: Endangered (EN)
EU 27 regional assessment: Critically Endangered (CR)

Globally, the species has undergone a large population decline, but local populations are still surviving in many parts of its range (rivers draining to Black, Azov and Caspian Seas; Siberia from Ob eastward to Yenisei drainages). Recorded catches in the Russian Federation decreased by nearly 40% between 1990 (116 tonnes) and 1996 (80.6 tonnes). It is stocked in large numbers in Danube range states and Russia (but it is unknown if the stocked individuals reproduce in the wild). It is impossible to identify the exact rate of decline of wild individuals and while some populations, e.g. Don (estimated >80% decline), Kuban (estimated >80% decline), Ob (<50% decline, Ruban pers. comm.), Irtysh (<50% decline, Ruban pers. comm.) and Dniester (>80% decline), have declined heavily, other stocks, e.g. Yenisey (estimated 40% decline), upper Volga (possibly stable but large stocking, Mugue pers. comm.), Ural (unknown decline), have seen smaller declines. Overall, the wild native population (excluding stocked individuals) is estimated to have declined by 60–70% over the last three generations. However, many populations of this species have undergone serious and dramatic declines in recent years and they need immediate conservation action.

It is assumed that the population is in decline at the same rate in its European range. Therefore, this species is assessed regionally for Europe as Endangered.

The EU 27 range corresponds to the Danube and its confluences only. Here the population has been substantially affected by habitat loss and damming. Over the past three generations, it is inferred that there has been an 80% population decline. Therefore, this species is assessed regionally for the EU 27 as Critically Endangered.

In Europe, this species is found in rivers and their estuaries. It occurs in the Black and Azov Sea basins. Its current strongholds are the Volga, Ural and Danube systems. In Russia it has been introduced in the Pechora drainage in 1928–1950 and in the Lake Ladoga basin (not self-sustaining). Aquaculture has resulted in intentional as well as accidental introductions throughout Europe, without establishing self-sustaining populations. This species has maintained self-sustaining populations in several impounded river sections in Russia.

Globally, the distribution of this species extends to parts of the Black, Azov and Caspian Sea basins outside of Europe, and in Siberia.

This species is very widespread and occurs in many populations. No monitoring data are available covering the whole range and all populations of the species. Within the last 60 years (three generations is somewhere between 53 and 78 years for this species) the population is believed to have declined by 60–70% across its range due to a wide number of threats. Naturally, some populations are more heavily affected than others. Few detailed data are available.

Comprehensive catch data are not currently available, but recorded catches in the Russian Federation decreased by nearly 40% between 1990 (116 tonnes) and 1996 (80.6 tonnes) (CITES 2000).

In the Danube drainage, the only available catch data are from 1958 to 1981 where catches ranged from 117 tonnes in 1963 to 36 tonnes in 1979, with an average catch of 63.5 tonnes per year (CITES 2000). In the middle and lower Danube the species is subject to a commercial fisheries ban which began in 2016. Catches are often unreported, therefore catch data are uncertain. Ten tonnes were reported annually for the late nineties in Hungary, with a sharp decline after the construction of Gabcikovo Dam (Guti 2011). Surveys (Juvenile Production Index) show annual reproduction and recruitment in the Romanian Danube and in the Serbian section of the Danube upstream the dams (Paraschiv et al. 2006, Knight et al. 2010) while reproduction in the Hungarian and Slovakian part seems to have dropped to a very low level (Pekarik pers. comm., Guti pers. comm.). In the middle Danube the species supported large scale fisheries at the end of the 19th century. Over the past 20 years a substantial decline was observed in this section of the Danube, which has not been estimated reliably. Remaining populations are fragmented by numerous dams without appropriate fish passage facilitation. Although separated by dams, recent genetic data showed that the Danube harbours a panmictic population (Friedrich et al. 2022) and should be managed as whole therefore.

Release programmes are supporting populations in the Ukrainian river (Dnjester, Dnjeper, and Don), while natural reproduction and harvest are reported to still be ongoing (WWF Ukraine).

The species is abundant in the Volga and Kuban rivers, with massive stocking programmes in place to support the latter.

The Sterlet is found in large rivers, usually in the current and in deep water. As water level rises, it moves to flooded areas to feed. It spawns on gravel in strong-current habitats.

The Sterlet is a potamodromous freshwater species. Males reproduce for the first time at three to five years, and females at five to eight years. The average age at first reproduction is about six years. Females reproduce every one to two years and males every year in April-June when the temperature rises above 10 °C.

Across its global distribution, Sterlet has generation lengths within the range 17.6–26 years; three generations for the species is somewhere between 53 and 78 years.

This species is largely sedentary; undertaking only short spawning migrations (322 km reported from the Danube). There was a migratory population with large-growing individuals in the Volga River until the end of the 19th century, feeding in the northern Caspian Sea and moving upriver in autumn. The Sterlet feeds on a wide variety of benthic insect larvae and molluscs.

Bycatch and overfishing, mostly for meat, are the major threats to the species. Modifications of river hydromorphology led to a loss of habitat and productivity in many rivers throughout its range, decreasing the carrying capacity.

Dam construction, which began in the 1930s, led to the loss of spawning grounds across the species' range, limiting migration and genetic exchange. Now, spawning success is reliant upon the remaining available habitat and the discharge being released by hydroelectric power stations.

Pollution, including oil products, phenols, PCBs and mercury, as well as nutrients, has threatened the species in the Danube, Volga system and Siberian rivers.

Outbreeding between populations induced by unregulated releases, as well as hybridisation, are an additional risk for the species. For example, the Danube population is affected by released or escaped fish of Caspian origin (Reinartz et al. 2011, Friedrich et al. 2022). In addition, hybridisation with non-native Siberian Sturgeon (Acipenser baerii) was found in the Danube River (Ludwig et al. 2009).

This species is exploited for caviar and meat for human consumption. It is also widely distributed in the ornamental fish trade.

Most range states have legislation regulating or banning the catch of the species, and there are stocking programmes for the Danube and Drava rivers. Restocking of the species is reported in Austria, Germany, Bulgaria, Hungary, Romania, Slovakia, Ukraine, and Russian Federation. This species was listed on CITES Appendix II in 1998. The species is included in the Pan European Action Plan for Sturgeons as well as the EU Flora-Fauna Habitats-Directive, the Bern Convention, the Bonn Convention and the EU regulation of trade of flora and fauna.