Parliament approves a 554-hectare Rioni area to protect sturgeon

The bill is a government initiative. Deputy Minister of Environmental Protection and Agriculture Zurab Ezugbaia presented it to parliament. On 27 May parliament adopted it in the first reading under an expedited procedure; on 28 May it passed the third reading with 74 votes.

Parliament’s Georgian-language releases call the new unit “Rioni aghkvetili”. It lies in Samtredia Municipality, Imereti, covers 554 hectares and includes the section of the Rioni where sturgeon spawn.

The amendments do more. They update the boundaries of Kolkheti National Park and its marine area, and set the geographic coordinates of the Rioni area and of the Kolkheti Multiple-Use Area. They list the activities allowed there: scientific research, monitoring, restoration work and restricted transport movement. They also set special rules for fishing and for the use of watercraft. Parliament’s releases do not give the details of those rules.

The Rioni is the largest river in western Georgia, 327 km long. It is one of the main eastern tributaries of the Black Sea and one of the shortest rivers in which sturgeon spawn. Historically, 5–7 sturgeon species were known from Georgia. Tamar Beridze’s doctoral thesis, defended at Ilia State University in 2023, calls Georgia a global hotspot of sturgeon diversity.

Sturgeons are among the most endangered groups of animals. A 2022 paper in Conservation Genetics notes that all sturgeon species of the Rioni and the eastern Black Sea are listed as Critically Endangered, and some are locally extinct. For the Rioni, this matters most for the ship sturgeon (below).

The status below follows Beridze’s thesis (2023), which identified species with genetic markers. Spawning was shown by finding juveniles.

Russian sturgeon (Acipenser gueldenstaedtii): spawns in the Rioni; juveniles were found in the river and at its mouth. It is the most abundant species.

Stellate sturgeon (Acipenser stellatus): spawns in the Rioni, juveniles found, but it is much rarer. Natural hybrids with Russian sturgeon were found.

Ship sturgeon (Acipenser nudiventris): spawns in the Rioni and was found only in the river. Recorded fish measured 10 to 75 cm.

Beluga (Huso huso): persists in Georgia’s Black Sea waters, but only adults were found and no juveniles. Whether it still spawns in Georgian rivers is unknown.

Siberian sturgeon (Acipenser baerii): not native. Three fish were found in the Rioni and on the Black Sea coast at Grigoleti.

The same markers did not detect Acipenser sturio, Acipenser persicus colchicus or Acipenser colchicus.

The ship sturgeon is Critically Endangered on the IUCN Red List. In the 20th century it vanished from the Aral, Azov and Black Seas and almost disappeared from the Caspian. It was considered regionally extinct in the Black Sea basin and had not been recorded in Georgia for three decades.

In 2020–2022, 22 ship sturgeon sightings were collected on the Rioni, including 9 genetic samples from fin clips. All nine share one mitochondrial haplotype that differs from every ship sturgeon haplotype in GenBank: by two nucleotides from the Caspian Sea haplotype and by seven from the Ili River (Balkhash basin) haplotype. The samples showed no sign of hybridisation.

Beridze’s thesis adds that the Rioni haplotype also differs from known commercial ship sturgeon haplotypes, so the fish did not come from the Krasnodar sturgeon gene-pool centre or from farms. The 2022 paper in Diversity calls them a remnant of an older Black Sea population. The thesis concludes that the Rioni population is likely the last surviving wild ship sturgeon population in the world.

Dams. After the Vartsikhe hydropower cascade was built (1968–1987), the stretch of the middle Rioni suitable for sturgeon spawning shrank from an estimated 57 km to 9 km, about 16% of its former length. The thesis also names poaching, gravel mining and pollution as pressures.

Hybridisation. Among 94 samples collected in 2018–2020, four juveniles turned out to be hybrids between Russian and stellate sturgeon: the first evidence of natural hybridisation in the Rioni. This cross is not used in aquaculture and there is no stellate sturgeon hatchery in the area, so farm escape was ruled out. The authors suggest that the low density of stellate sturgeon makes it harder to find a mate of its own species. The thesis reports six such hybrids, all with a Russian sturgeon mother.

Non-native Siberian sturgeon. Of the three fish (two juveniles and one adult), the adult, a 90 cm male, was found in August 2020 near Samtredia, close to a likely spawning ground. It is a commercial species and may have escaped or been released from aquaculture. The thesis sees it as a possible threat to native sturgeon.

Illegal trade. Samples from Georgian fish markets and farms (2016–2020) contained four species: Russian sturgeon, stellate sturgeon, beluga and sterlet (Acipenser ruthenus). Russian sturgeon made up almost 92%. Genetic markers separated wild from farmed Russian sturgeon and showed that wild genotypes were sold in Georgian fish markets, especially in coastal markets of western Georgia. The thesis notes that such sales are illegal.

The category. Georgian releases use “aghkvetili”. Parliament’s English releases call the area “Rioni Managed Reserve” at the first reading and “Rioni Strict Nature Reserve” at the third. These are different categories. The final category is set by the official text of the law on matsne.gov.ge, which we have not yet checked.

Implementation. We have no information on whether the area is already managed or protected on the ground, or on the details of its fishing and watercraft rules.

The science. The sources used here give no estimate of sturgeon numbers in the Rioni. Whether beluga spawn in Georgia is unknown. Estimates of the lost spawning stretch differ: the thesis also cites a reduction from about 90 km to 9 km. “Last wild population” is the thesis authors’ cautious conclusion; an introduced population of Aral origin lives in the Ili River in Kazakhstan. The market study was a manuscript in preparation when the thesis was submitted.

Sturgeons are not in this atlas. See other news for more records.