The Amu Darya sturgeon or false shovelnose sturgeon (''Pseudoscaphirhynchus kaufmanni'') is a

critically endangered An IUCN Red List critically endangered (CR or sometimes CE) species is one that has been categorized by the International Union for Conservation of Nature as facing an extremely high risk of extinction in the wild. As of December 2023, of t ...

species of fish in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Acipenseridae 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 ...

. It is found in

Turkmenistan Turkmenistan is a landlocked country in Central Asia bordered by Kazakhstan to the northwest, Uzbekistan to the north, east and northeast, Afghanistan to the southeast, Iran to the south and southwest and the Caspian Sea to the west. Ash ...

Uzbekistan , image_flag = Flag of Uzbekistan.svg , image_coat = Emblem of Uzbekistan.svg , symbol_type = Emblem of Uzbekistan, Emblem , national_anthem = "State Anthem of Uzbekistan, State Anthem of the Republ ...

Tajikistan Tajikistan, officially the Republic of Tajikistan, is a landlocked country in Central Asia. Dushanbe is the capital city, capital and most populous city. Tajikistan borders Afghanistan to the Afghanistan–Tajikistan border, south, Uzbekistan to ...

and perhaps

Afghanistan Afghanistan, officially the Islamic Emirate of Afghanistan, is a landlocked country located at the crossroads of Central Asia and South Asia. It is bordered by Pakistan to the Durand Line, east and south, Iran to the Afghanistan–Iran borde ...

. It inhabits quite shallow flowing waters that are turbid and muddy.Birstein, V.J.; J.R. Waldman; and W.E. Bemis, editors (1997). Sturgeon biodiversity and conservation, pp. 377–378, 381–382. Kluwer Academic Publishing.

Appearance

Pseudoscaphirhynchus kaufmanni 1996 stamp of Kyrgyzstan

The Amu Darya sturgeon is a small sturgeon, but the largest species of ''

Pseudoscaphirhynchus ''Pseudoscaphirhynchus'' is a genus of relatively small, highly threatened sturgeons that are restricted to the Aral Sea system (although Local extinction, extirpated from the Aral Sea itself), including the Amu Darya and Syr Darya river basins, ...

'', reaching up to in weight and in total length, excluding tail filament. It has a long, thin tail filament. For example, two individuals that both had a length of about excluding tail filament were and including tail filament. The species occurs in two morphs: a relatively large, light-coloured and late maturing morph, and a small, dark-coloured and early maturing morph. The small morph is roughly of similar size to '' P. hermanni'', a species that lacks a tail filament.

Behavior

The Amu Darya sturgeon feeds on small fish and aquatic insect larvae, with large individuals being mostly

piscivorous A piscivore () is a carnivorous animal that primarily eats fish. Fish were the diet of early tetrapod evolution (via water-bound amphibians during the Devonian period); insectivory came next; then in time, the more terrestrially adapted rept ...

. Studies in the 1960s and 1970s showed that Amu Darya sturgeon reach maturity when 5–8 years old (slightly later in females than males), but in the 1990s the youngest mature individuals only were 4 years old, possibly due to environmental changes in their habitat. The breeding season is from March to May when the water is . During a season, a female of the large morph lays about 3,100–36,500 eggs and a female of the small morph about 1,000–2,000 eggs, but it is possible that they only do this every 4–5-year. The species can reach an age of more than 14 years. Historically, it was known to hybridize with ''P. hermanni'', with the offspring having features that are intermediate between the two species.

Conservation status

The Amu Darya sturgeon once occurred throughout the

Amu Darya The Amu Darya ( ),() also shortened to Amu and historically known as the Oxus ( ), is a major river in Central Asia, which flows through Tajikistan, Turkmenistan, Uzbekistan, and Afghanistan. Rising in the Pamir Mountains, north of the Hindu Ku ...

river basin, including its delta in the

Aral Sea The Aral Sea () was an endorheic lake lying between Kazakhstan to its north and Uzbekistan to its south, which began shrinking in the 1960s and had largely dried up into desert by the 2010s. It was in the Aktobe and Kyzylorda regions of Kazakhst ...

, today it is found in the middle Amu Darya River (between

Kerki Kerki is a city in and capital of Kerki District, Lebap Province, Turkmenistan. It was formerly known as Zamm and, between 1999 and 2017, as Atamyrat. Geography It is situated on a plain on the left bank of the Amu Darya river. Nearby towns a ...

and Chardzhou (modern name is Turkmenabad) in Turkmenistan and also lower in Kyzylrabat area (Uzbekistan), also in more lower Amu Darya River (between Pitnak and Urganch in Khorezm province, Uzbekistan) and in the lower Vakhsh River (an Amu Darya tributary) in Tajikistan. It has declined because of habitat loss, pollution and poaching, and is rated as

by the

IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...

. Despite its threatened status, strong decline and range contraction, it can be locally fairly common and overall it is the least rare species of ''Pseudoscaphirhynchus'' ('' P. fedtschenkoi'' is possibly extinct and ''P. hermanni'' only survives in very small numbers).Salnikov, V.B.; V.J. Birstein; and R.L. Mayden (1996). The contemporary status of the two Amu Darya River shovelnose sturgeons, Pseudoscaphirhynchus kaufmanni and P. hermanni. The Sturgeon Quarterly 4(3): 10–14. In general the status of the Amu Darya sturgeon is poorly known and further surveys are necessary. A part of its range is in the Amudarya State Nature Reserve. Although the Amu Darya sturgeon is a fully protected species throughout its range,Mikodina, E.; and A. Novosadova (2015). Rare Acipenserids in Russian Aquaculture. ВОПРОСЫ РЫБНОГО ХОЗЯЙСТВА БЕЛАРУСИ 31: 38–51.

illegal fishing Illegal, unreported and unregulated fishing (IUU) is an issue around the world. Fishing industry observers believe IUU occurs in most fisheries, and accounts for up to 30% of total catches in some important fisheries. Illegal fishing takes pl ...

is widespread and fisheries management in the region is very poor.UNEP-WCMC. (2013). UNEP-WCMC, Cambridge. The species has been listed on

CITES Appendix II CITES (shorter acronym for the Convention on International Trade in Endangered Species of Wild Fauna and Flora, also known as the Washington Convention) is a multilateral treaty to protect endangered plants and animals from the threats of inte ...

since 1998. This restricts international trade in the species, but two were legally exported from Uzbekistan to Russia for zoological purposes in 2002–2012, and in 2013 Uzbekistan set the export quota to twenty individuals. Many sturgeon species have been bred in captivity and this often forms the basis for restocking the wild populations. In the 1980s there were attempts of doing this with the Amu Darya sturgeon. Although some progress was made, captive breeding ultimately failed because the embryos died. Since 2010, Eurasian Regional Association of Zoos and Aquariums (EARAZA) together with various Russian and Uzbekistan institutes as well as officials of Tajikistan) has attempted to start a breeding program for the Amu Darya sturgeon, but as of 2021 it has not succeeded (in 2020 Khorezm Mamun Academy in Khiva (Khorezm province branch of Academy of Sciences of Uzbekistan) - the main partner in the program) has temporary stopped shovelnose conservation project because of lack of financial support) although some progress was made (the eggs were incubated in the field in 2012 but the embryos died).

Taxonomy

The

karyotype A karyotype is the general appearance of the complete set of chromosomes in the cells of a species or in an individual organism, mainly including their sizes, numbers, and shapes. Karyotyping is the process by which a karyotype is discerned by de ...

of the Amu Darya sturgeon consists of roughly 118–120

chromosome A chromosome is a package of DNA containing part or all of the genetic material of an organism. In most chromosomes, the very long thin DNA fibers are coated with nucleosome-forming packaging proteins; in eukaryotic cells, the most import ...

s; it is classified as a low-chromosome group acipenserid fish. Studies of its

genetics Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinians, Augustinian ...

and karyotype show clear differences compared to the shovelnose sturgeon (''Scaphirhynchus platorhynchus''), indicating that the usually recognized subfamily

Scaphirhynchinae Sturgeon (from Old English ultimately from 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 Late Cretaceous, and are desce ...

polyphyletic A polyphyletic group is an assemblage that includes organisms with mixed evolutionary origin but does not include their most recent common ancestor. The term is often applied to groups that share similar features known as Homoplasy, homoplasies ...

. Further karyological research on the Amu Darya sturgeon may help in determining

polyploid Polyploidy is a condition in which the biological cell, cells of an organism have more than two paired sets of (Homologous chromosome, homologous) chromosomes. Most species whose cells have Cell nucleus, nuclei (eukaryotes) are diploid, meaning ...

evolution in acipenserid fish.

References

External links

Large Amu Darya Shovelnose Sturgeon (Pseudoscaphirhynchus kaufmanni) digital morphology

Large Amu Darya Shovelnose Sturgeon (Pseudoscaphirhynchus kaufmanni) at FishBase

Large Amu Darya Shovelnose Sturgeon (Pseudoscaphirhynchus kaufmanni) in the lower Amu Darya River (Uzbekistan)

Large Amu Darya Shovelnose Sturgeon (Pseudoscaphirhynchus kaufmanni) in the lower Vakhsh River (an Amu Darya tributary) in Tadjikistan

Large Amu Darya Shovelnose Sturgeon (Pseudoscaphirhynchus kaufmanni) in the middle Amu Darya River (Uzbekistan)

Large Amu Darya Shovelnose Sturgeon (Pseudoscaphirhynchus kaufmanni) in the middle Amu Darya River (Turkmenistan)
* V.B. Sal’nikov, N.V. Akimova, G.I. Ruban, R.L. Mayden, B.R. Kuhajda. Reproductive System of Amu-Dar Shovelnoses - Big Shovelnose Pseudoscaphirhynchus kaufmanni and Little Shovelnose P. hermanni (Acipenseridae). Journal of Ichthyology, Vol. 43, No. 7, 2003, pp. 516–527. Translated from Voprosy Ikhtiologii, Vol. 43, No. 4, 2003, pp. 499–510: http://life-on-earth.ru/images/Salnikov-Amudarya_Shovelnose_Reproductive_System.pdf * V.B. Sal’nikov, R.L. Mayden, B.R. Kuhajda. Tagging of the Big Amu-Dar Shovelnose Pseudoscaphirhynchus kaufmanni (Acipenseridae). Journal of Ichthyology, Vol. 44, No. 9, 2004, pp. 778–782. Translated from Voprosy Ikhtiologii, Vol. 44, No. 6, 2004, pp. 832–836: http://life-on-earth.ru/images/Salnikov-Amudarya_Shovelnose_Tagging.PDF * Bernard R. Kuhajda (University of Alabama, USA), Richard L. Mayden (St.Louis University, USA), Vladimir. B. Sal’nikov (National Institute of Deserts, Flora and Fauna, Turkmenistan). Evolutionary and Conservation Studies of Imperiled Sturgeon Species of the Genus Pseudoscaphirhynchus in Central Asia. Report, 2007. Copyright 2016, All Rights Reserved: http://life-on-earth.ru/images/Lopatonosy-Turkmenistan/Salnikov-Amudarya_Shovelnose_Sturgeon_Eng.pdf * C. B. Dillman, R. M. Wood, B. R. Kuhajda, J. M. Ray, V. B. Salnikov, R. L. Mayden. Molecular systematics of Scaphirhynchinae: an assessment of North American and Central Asian Freshwater Sturgeon Species. Journal of Applied Ichthyology, 23 (2007), pp. 290–296: http://life-on-earth.ru/images/Lopatonosy-Turkmenistan/Molecular_systematics_of_Scaphirhynchinae.pdf {{Taxonbar, from=Q1507886 Pseudoscaphirhynchus Freshwater fish of Asia Fish of Central Asia Fauna of Tajikistan Critically endangered fish Critically endangered fauna of Asia Taxonomy articles created by Polbot Fish described in 1877 Amu Darya