The Caucasian sturgeon or Colchis sturgeon (''Huso colchicus'') is a highly endangered
species
A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
of
sturgeon
Sturgeon (from Old English ultimately from Proto-Indo-European language, Proto-Indo-European *''str̥(Hx)yón''-) is the common name for the 27 species of fish belonging to the family Acipenseridae. The earliest sturgeon fossils date to the ...
native to the eastern Europe and western Asia, where it is found in the southeastern
Black Sea
The Black Sea is a marginal sea, marginal Mediterranean sea (oceanography), mediterranean sea lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bound ...
& associated river basins, as well as the lower
Danube River
The Danube ( ; see also other names) is the second-longest river in Europe, after the Volga in Russia. It flows through Central and Southeastern Europe, from the Black Forest south into the Black Sea. A large and historically important riv ...
. It is named after the historic region of
Colchis
In classical antiquity and Greco-Roman geography, Colchis (; ) was an exonym for the Georgian polity of Egrisi ( ka, ეგრისი) located on the eastern coast of the Black Sea, centered in present-day western Georgia.
Its population, the ...
.
It was long considered a
subspecies
In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...
of the
Russian sturgeon
The Russian sturgeon (''Huso gueldenstaedtii''), also known as the diamond sturgeon or Danube sturgeon, is a species of fish in the family Acipenseridae. It is found in Azerbaijan, Bulgaria, Georgia, Iran, Kazakhstan, Romania, Russia, Turkey, Tur ...
(''H. gueldenstaedtii'') or the Persian sturgeon (''H. persicus''), which themselves were previously placed in the genus ''
Acipenser
''Acipenser'' is a genus of sturgeons, containing three species native to freshwater and estuarine systems of eastern North America and Europe. It is the type genus of the family Acipenseridae and the order Acipenseriformes.
Taxonomy
Prior t ...
''. However, recent phylogenetic studies have reclassified both into ''
Huso
''Huso'' is a genus of sturgeons from eastern Europe, Asia, and eastern North America. The genus name is derived from ''wikt:huso, hūso'', the Old High German and Medieval Latin word for "sturgeon", which is also ancestral to ''wikt:Hausen, Haus ...
'', and have affirmed the distinctiveness of the Caucasian sturgeon from both of these species. Phylogenetic evidence indicates that the Caucasian sturgeon is most closely related to the
Adriatic sturgeon
The Adriatic sturgeon (''Huso naccarii'') is a species of fish in the family Acipenseridae. It is native to the Adriatic Sea and large rivers which flow in it of Albania, Greece, Italy, Montenegro, Croatia, Bosnia and Herzegovina and Slovenia.
...
(''H. naccarii''). It cannot be properly differentiated from the Russian sturgeon by morphology alone, and very little has been studied about its phylogenetics.
It is known from
Romania
Romania is a country located at the crossroads of Central Europe, Central, Eastern Europe, Eastern and Southeast Europe. It borders Ukraine to the north and east, Hungary to the west, Serbia to the southwest, Bulgaria to the south, Moldova to ...
,
Bulgaria
Bulgaria, officially the Republic of Bulgaria, is a country in Southeast Europe. It is situated on the eastern portion of the Balkans directly south of the Danube river and west of the Black Sea. Bulgaria is bordered by Greece and Turkey t ...
,
Turkey
Turkey, officially the Republic of Türkiye, is a country mainly located in Anatolia in West Asia, with a relatively small part called East Thrace in Southeast Europe. It borders the Black Sea to the north; Georgia (country), Georgia, Armen ...
, and
Georgia
Georgia most commonly refers to:
* Georgia (country), a country in the South Caucasus
* Georgia (U.S. state), a state in the southeastern United States
Georgia may also refer to:
People and fictional characters
* Georgia (name), a list of pe ...
. It is found in the
Danube
The Danube ( ; see also #Names and etymology, other names) is the List of rivers of Europe#Longest rivers, second-longest river in Europe, after the Volga in Russia. It flows through Central and Southeastern Europe, from the Black Forest sou ...
,
Rioni
The Rioni ( ka, რიონი ; , ) is the main river of western Georgia. It originates in the Caucasus Mountains, in the region of Racha and flows west to the Black Sea, entering it north of the city of Poti (near ancient Phasis). The city ...
,
Enguri
The Enguri ( ka, ენგური, tr , , , ''Egry'') is a river in western Georgia (country), Georgia. It is long, and has a drainage basin of .Tskhenistskali, Coruh, Yeşilırmak, Kızılırmak and
Sakarya
Sakarya may refer to:
Places
* Sakarya (continent), a small continent 90 million years ago
* Sakarya, Ardanuç, a village in Artvin Province, Turkey
* Sakarya, Polatlı, a village in Ankara Province, Turkey
* Sakarya gas field, in the Black Sea
* ...
river basins. The primary remaining spawning area for the species is the Rioni River of Georgia. Even in this habitat, it is known to hybridize with the stellate sturgeon (''Huso stellatus''), although offspring are infertile. Spawning populations in the Danube, if they still exist, are thought to be very small. The
Colchic Rainforests and Wetlands
The Colchic Rainforests and Wetlands () is a UNESCO World Heritage Site in Georgia (country), Georgia, which comprises parts of the Colchis Lowland along some of western Georgia's Black Sea coastline. It was List of World Heritage Sites by year of ...
are an important refuge for the species. The species has been successfully raised in captivity in Georgia for both conservation purposes and
caviar
Caviar or caviare is a food consisting of salt-cured roe of the family Acipenseridae. Caviar is considered a delicacy and is eaten as a garnish or spread. Traditionally, the term caviar refers only to roe from wild sturgeon in the Caspi ...
production, with nearly 600 specimens being bred as of 2022.