Sturgeons are long-lived, late-maturing fishes with distinctive characteristics, such as aheterocercal caudal fin similar to those ofsharks, and an elongated, spindle-like body that is smooth-skinned, scaleless, and armored with five lateral rows of bony plates calledscutes. Several species can grow quite large, typically ranging 2–3.5 m (7–12 ft) in length. The largest sturgeon on record was abeluga female captured in theVolga Delta in 1827, measuring 7.2 m (23 ft 7 in) long and weighing 1,571 kg (3,463 lb). Most sturgeons areanadromousbottom-feeders, migrating upstream to spawn but spending most of their lives feeding inriver deltas andestuaries. Some species inhabit freshwater environments exclusively, while others primarily inhabit marine environments nearcoastal areas, and are known to venture into open ocean.
Several species of sturgeon are harvested for theirroe, which is processed into theluxury foodcaviar. This has led to seriousoverexploitation, which combined with other conservation threats, has brought most of the species tocritically endangered status, at the edge ofextinction.
Apparent cognates to Sturgeon might be found in Baltic, Germanic, Greek, Romance, and Slavic languages. The trade of sturgeon in ancient Europe would cause for the root word for these to spread across the region. Many potential reconstructions may place it as either a non-Indo-European substrate language,[6] possibly from around the Volga river where sturgeon could be caught and sold, while others reconstruct aProto-Indo-European source.
One reconstruction links Sturgeon to ultimately derive from Proto-Indo-European *str̥(Hx)yón-.[7]
Acipenseriform fishes appeared in the fossil record some 174 to 201 million years ago, during theEarly Jurassic, making them some of the earliest extantactinopterygian fishes.[8] Sturgeons must have diverged from their closest relatives, thepaddlefish, during theEarly Cretaceous (125-120 million years ago) or prior, as the earliest fossil paddlefish (Protopsephurus) is known from then.[9] True sturgeons appear in the fossil record during the UpperCretaceous, with amongst the oldest known remains being a partial skull from theCenomanian (100–94 million years ago) of Alberta, Canada.[10] In that time, sturgeons have undergone remarkably littlemorphological change, indicating their evolution has been exceptionally slow and earning them informal status asliving fossils.[11][12] This is explained in part by the long generation interval, tolerance for wide ranges oftemperature andsalinity, lack ofpredators due to size and bony plated armor, or scutes, and the abundance of prey items in the benthic environment. They do, however, still share several primitive characteristics, such as heterocercal tail, reduced squamation, more fin rays than supporting bony elements, and unique jaw suspension.[13]
Despite the existence of afossil record, full classification andphylogeny of the sturgeon species has been difficult to determine, in part due to the high individual andontogenic variation, including geographicalclines in certain features, such as rostrum shape, number of scutes, and body length. A further confounding factor is the peculiar ability of sturgeons to produce reproductively viablehybrids, even between species assigned to differentgenera. While ray-finned fishes (Actinopterygii) have a long evolutionary history culminating in the most familiar fishes, past adaptiveevolutionary radiations have left only a few survivors, such as sturgeons andgars.[14]
The wide range of the acipenserids and their endangered status have made collection of systematic materials difficult. The factors have led researchers in the past to identify over 40 additional species that were rejected by later scientists.[18] An effort is ongoing to resolve the taxonomic confusion using a continuing synthesis of systematic data andmolecular techniques.[12][19]
A fossil sturgeon (right) from theTanis fossil site, showing the longstanding morphological conservatism of this group
Sturgeons are a highly morphologically conservative group, to the extent that lineages that (based on molecular data) have been separate since theCretaceous period can physically appear very similar, and mistakenly classified as each other's closest relatives. In the classic taxonomic treatment, Acipenseridae was subdivided into 2 subfamilies;Acipenserinae, including the generaAcipenser andHuso, andScaphirhynchinae, including the generaScaphirhynchus andPseudoscaphirhynchus.[20] Under a phylogeny that exclusively incorporates morphological data, sturgeons appear to comprise two groups that diverged during the Cretaceous: aScaphirhynchus lineage, and aAcipenser+Huso+Pseudoscaphirhynchus lineage. The latter seemingly appears rather young compared to the age of the group as a whole, with much of its radiation only occurring during theLate Paleogene andNeogene.[2]
However, with the advent ofmolecular phylogenetics, multiple studies since the 1990s have recovered this arrangement asparaphyletic, instead findingA. oxyrhinchus andA. sturio to form the mostbasal clade among sturgeons, and all other species being in a separate clade, with the various other species ofAcipenser,Scaphirhynchus,Pseudoscaphirhynchus, andHuso to have varying levels of relationship with one another. The morphologically distinct "shovelnose" type sturgeons are deeply nested within the former "Acipenser" and "Huso" clades. The divergences within the group have also been found to be much deeper, withAcipensersensu stricto diverging from the rest of the group well into the Cretaceous. The other lineages were found to have diverged from one another during the Late Cretaceous and Paleogene.[21][19][22][23]
The exact placement ofScaphirhynchus varies depending on the study and the methods used, with some placing it within the second-most basal clade comprising primarily Pacific species, whereas others place it in its own clade that is more derived than the secondmost basal clade but less derived than the most derived Atlantic and Central Asian clade. No studies have yet delineated a relationship between it andPseudoscaphirhynchus. In addition, the exact relationships of the members of the mostderived, primarily Atlantic clade vary, although most analyses at least find all the species in it to form a monophyletic clade. The placement ofA. sinensis also varies by the study, with some placing it as the only Pacific member of the otherwise Atlantic-based most-derived clade, whereas others place it with the rest of the Pacific sturgeons as a sister toA. dabryanus.[22][23]
Brownstein &Near (2025) used DNA sequencing and morphological data to establish 5monophyletic genera for Acipenseridae and mostly resolve the longstanding confusion over clade names. The 5 clades found wereAcipensersensu stricto,Scaphirhynchus,Pseudoscaphirhynchus,Huso, and the revived genusSinosturio, as well as moving species out ofAcipenser and into the latter two genera (including the kaluga, nowSinosturio dauricus).[1][2]
The following taxonomy is based on Brownstein & Near, 2025:[2]
TheAtlantic sturgeon (A. oxyrhynchus) is one of the mostbasal sturgeon speciesShovelnose sturgeons (Scaphirhynchus platorynchus) are morphologically atypical members of the groupThebeluga sturgeon (Huso huso) is one of the largest sturgeon speciesTheSyr Darya sturgeon (Pseudoscaphirhynchus fedtschenkoi) is likely extinct
Illustration of the dubious fossil species "Acipenser"gigantissimus from theLate Cretaceous (Maastrichtian) of Russia
Fossil sturgeons are known from the mid-lateCretaceous onwards. The earliest known sturgeon fossil is of an indeterminate partial skull from theCenomanian-agedDunvegan Formation of Alberta, Canada.[10] It was previously assumed that fromAsiacipenser kotelnikoviNessov, 1990 from theLate Jurassic of Kazakhstan was the earliest sturgeon, but these remains are non-diagnostic and it is unlikely that it represents a member of the family.[24] They become particularly diverse during theLate Cretaceous of North America, where multiple different genera are known.
Genus †PriscosturionGrande& Hilton, 2009 (=PsammorhynchusGrande & Hilton, 2006)[24]
†Priscosturion longipinnis(Grande & Hilton, 2006) (Late Cretaceous of Alberta, Canada)
Most fossil species placed in "Acipenser" are thought to benomina dubia, being based on fragmentary remains that do not display diagnostic traits.[24] The exceptions are"A."praeparatorum and"A."anisinferos from theHell Creek Formation, which are known from well-preserved remains.[25]A. praeparotorum may potentially represent a basal member of theHuso-Pseudoscaphirhynchus lineage.[2]
Throughout this extensive range, almost all species are highly threatened or vulnerable to extinction due to a combination ofhabitat destruction, overfishing, and pollution.[20]
No species is known to naturally occur south of the equator, though attempts at sturgeonaquaculture are being made inUruguay,South Africa, and other places.[31]
Most species are at least partiallyanadromous,spawning in fresh water and feeding in nutrient-rich, brackish waters ofestuaries or undergoing significant migrations along coastlines. However, some species have evolved purely freshwater existences, such as thelake sturgeon (Acipenser fulvescens) and theBaikal sturgeon (A. baerii baicalensis), or have been forced into them by human or naturalimpoundment of their native rivers, as in the case of some subpopulations ofwhite sturgeon (A. transmontanus) in theColumbia River[32] andSiberian sturgeon (A. baerii) in the Ob basin.[33]
Sturgeon skull – a, Rostrum; b, nasal capsule; c eye-socket; d, foramina for spinal nerves; e, notochord; g, quadrate bone; h, hyomandibular bone; i, mandible; j. basibranchials; k, ribs; l, hyoid bone; I, II, III, IV, V, branchial arches
Sturgeons retain several primitive characteristics from the bony fishes. Along with other members of thesubclassChondrostei, they are unique among bony fishes because their skeletons are almost entirelycartilaginous. To maintain structure, sturgeons are one of few vertebrates to retain a post-embryonicnotochord that acts like a soft spine running through the body. Notably, however, the cartilaginous skeleton is not a primitive character, but a derived one; sturgeon ancestors had bony skeletons.[13][34][35] They also lackvertebral centra, and are partially covered with five lateral rows of scutes rather thanscales.[36] They also have fourbarbels—sensory organs that precede their wide, toothless mouths. They navigate their riverine habitats traveling just off the bottom with their barbels dragging along gravel, or murky substrate. Sturgeon are recognizable for their elongated bodies, flattenedrostra, distinctive scutes and barbels, and elongated upper tail lobes. The skeletal support for the paired fins of ray-finned fish is inside the body wall, although the ray-like structures in the webbing of the fins can be seen externally.
Sturgeons are among the largest fish: somebeluga (Huso huso) in theCaspian Sea reportedly attain over 5.5 metres (18 ft) and 2,000 kilograms (4,400 lb)[37] while forkaluga (H. dauricus) in theAmur River, similar lengths and over 1,000 kg (2,200 lb) weights have been reported.[38] They are also among the longest-lived of the fishes, some living well over 100 years and attaining sexual maturity at 20 years or more.[30] The combination of slow growth and reproductive rates and the extremely high value placed on mature, egg-bearing females make sturgeon particularly vulnerable tooverfishing.
Sturgeons arepolyploid; some species have four, eight, or 16 sets of chromosomes.[39]
Sturgeons are long-lived, late maturing fishes. Their average lifespan is 50 to 60 years, and their firstspawn does not occur until they are around 15 to 20 years old. Sturgeons are broadcast spawners, and do not spawn every year because they require specific conditions. Those requirements may or may not be met every year due to varying environmental conditions, such as the properphotoperiod in spring, clear water with shallow rock or gravelsubstrate, where the eggs can adhere, and proper water temperature and flow foroxygenation of the eggs. A single female may release 100,000 to 3 million eggs, but not all will be fertilized. The fertilized eggs become sticky and adhere to the bottom substrate upon contact. Eight to 15 days are needed for the embryos to mature intolarval fish. During that time, they are dependent on their yolk sacs for nourishment.[40][41] River currents carry the larvae downstream into backwater areas, such asoxbows andsloughs, where the free-swimmingfry spend their first year feeding on insect larvae andcrustacea. During their first year of growth, they reach 18 to 20 cm (7 to 8 in) in length and migrate back into the swift-flowing currents in themain stem river.[42]
Sturgeons are primarilybenthic feeders, with a diet of shellfish, crustaceans, and small fish. Exceptionally, thebeluga sturgeon, thekaluga sturgeon, thewhite sturgeon and thepallid sturgeon all feed primarily on other fish as adults. They feed by extending their siphon-like mouths to suck food from thebenthos. Having no teeth, they are unable to seize prey, though larger individuals and more predatory species can swallow very large prey items, including wholesalmon.[43] Sturgeons feed non-visually. They are believed to use a combination of sensors, including olfactory, tactile, and chemosensory cues detected by the four barbels, andelectroreception using theirampullae of Lorenzini.[44]
The sturgeons' electroreceptors are located on the head and are sensitive to weak electric fields generated by other animals or geoelectric sources.[45] The electroreceptors are thought to be used in various behaviors such as feeding, mating and migration.[44]
Many sturgeons leap completely out of the water,[46] usually making a loud splash which can be heard half a mile away on the surface and probably farther under water. Why they do this is not known, but suggested functions include group communication to maintain group cohesion, catching airborne prey,courtship display, or to help shed eggs during spawning. Other plausible explanations include escape from predators, shedding parasites, or to gulp or expel air.[47] Another explanation is that it "simply feels good".[48] There have been some incidents of leaping sturgeon landing in boats and causing injuries to humans;[49] in 2015, a 5-year-old girl was fatally injured after a sturgeon leapt from theSuwannee River and struck her.[50]
In 1731, an observer of leaping sturgeon wrote:
...in May, June and July, the rivers abound with them, at which time it is surprising, though very common to see such large fish elated in the air, by their leaping some yards out of the water; this they do in an erect posture, and fall on their sides, which repeated percussions are loudly heard some miles distance....[48]
Beluga sturgeon at a caviar farm in South Korea.Woman selling sturgeon at a market inTürkmenbaşy, Turkmenistan
Globally, sturgeon fisheries are of great value, primarily as a source forcaviar, but also for flesh.[51] Several species of sturgeon are harvested for their roe which is processed into caviar—adelicacy, and the reason why caviar-producing sturgeons are among the most valuable and endangered of all wildlife resources.[52]
During the 19th century, the US was the global leader in caviar production, having cornered 90% of the world's caviar trade.[53] Atlantic sturgeon once thrived along the east coast from Canada down toFlorida. They were in such abundance in theHudson River that they werehumorously called "Albany beef" and sturgeon eggs were given away at local bars as an accompaniment to 5¢ beer.[54] White sturgeon populations along the US west coast declined simultaneously under the pressure of commercial fishing and human encroachment. Within the course of a century, the once abundant sturgeon fisheries in the US and Canada had drastically declined, and in some areas had been extirpated under the pressure of commercial overharvesting, pollution, human encroachment, habitat loss, and the damming of rivers that blocked their ancestral migration to spawning grounds.[53][55]
By the turn of the century, commercial production of sturgeon caviar in the US and Canada had come to an end. Regulatory protections and conservation efforts were put in place by state and federal resource agencies in the US and Canada, such as the 1998 US federal moratorium that closed all commercial fishing for Atlantic sturgeon.[55] It was during the 20th century that Russia grew to become the global leader as the largest producer and exporter of caviar.[53] As with the decline in sturgeon populations in the US and Canada, the same occurred with sturgeon populations in the Caspian Sea.[56]
Beginning with the 1979 US embargo on Iran,poaching and smuggling sturgeon caviar was big business but an illegal and dangerous one.[57] Officers with theWashington Department of Fish and Wildlife (WDFW) busted a poaching ring that was based inVancouver, Washington. The poachers had harvested 1.65 tons of caviar from nearly 2,000 white sturgeon that were poached from the Columbia River. The caviar was estimated to be worth around $2 million. WDFW busted another ring in 2003, and conducted an undercover sting operation in 2006–2007 that resulted in 17 successful attempts out of a total of 19.[58]
In response to concerns over the future of sturgeons and associated commercial products, international trade for all species of sturgeons has been regulated underCITES since 1998.[52]
Sturgeons are threatened by the negative impacts of overfishing, poaching,habitat destruction, and the construction of dams that have altered or blocked their annual migration to ancestral spawning grounds.[59][60][61] Some species of sturgeon are extinct, and several are on the verge of extinction, including theChinese sturgeon,[62] the highly prized beluga sturgeon,[63] and theAlabama sturgeon.[64] Many species are classified as threatened or endangered, with noticeable declines in sturgeon populations as the demand for caviar increases.IUCN data indicates that over 85% of sturgeon species are at risk of extinction, making them more critically endangered than any other group of animal species.[65][66]
In addition to global restocking efforts, the monitoring of populations and habitat, and various other conservation efforts by national and state resource agencies as applicable to their respective countries, several conservation organizations have been formed to assist in the preservation of sturgeons around the world. On a global scale, one such organization is theWorld Sturgeon Conservation Society (WSCS) whose primary objectives include fostering the "conservation of sturgeon species and restoration of sturgeon stocks world-wide", and supporting the "information exchange among all persons interested in sturgeons."[67] The North American Sturgeon and Paddlefish Society (NASPS)[68] and Gesellschaft zur Rettung des Störs e.V.[69] are WSCS affiliates. WSCS has been instrumental in organizing global conferences where scientists and researchers can exchange information and address the various conservation challenges that threaten the future of sturgeons.[70] Conservation efforts at the grass roots level are also instrumental in helping to preserve sturgeon populations, such as Sturgeon For Tomorrow[71] which was founded in 1977, consists of volunteers and a sturgeon guarding program to monitor known spawning sites. The organization has grown exponentially over the years and has become "the largest citizen advocacy group for sturgeon in the world", and has expanded with affiliate chapters in other states that have sturgeon populations.[72][73] Other projects focus on specific local issues, such as the We Pass project, seeking a solution to the migratory impasse represented by theIron Gates in the Danube River Basin.[74] For example, currently all anadromousDanube sturgeon (all species except the predominantly freshwater sterlet) are now classed as Critically Endangered or extirpated from the upper and middle reaches of the Danube River above the dams.[75]
The Jewish laws ofkashrut, which only permit the consumption of fish with both scales and fins, forbids sturgeon, as they haveganoid scales instead of the permittedctenoid andcycloid scales. While allOrthodox groups forbid the consumption of sturgeon, someConservative groups do allow it.[77] The theological debate over its kosher status can be traced back to such 19th-century reformers asAron Chorin, though its consumption was already common in European Jewish communities.[78]
Sturgeons were declared to be aroyal fish under a statute dating back to 1324 by KingEdward II of England. Technically, the British monarchy still owns all sturgeons,whales, anddolphins that inhabit the waters aroundEngland andWales.[79][80] Under the law of theUnited Kingdom, any sturgeons captured within the realm are personal property of the monarch.[81]
Similar laws reserving sturgeon for the king were enforced in late medieval Denmark. An archaeological example of sturgeon in a royal context comes from the wreck of the Danish-Norwegian flagship,Gribshunden, which sank in June 1495 while King Hans sailed from Copenhagen to Kalmar, Sweden for a diplomatic summit. Archaeologists recovered from the wreck a cask containing a butchered sturgeon, probably intended for the king's table during feasts in Kalmar.[82]
In heraldry, a sturgeon is the symbol on the coat of arms for SaintAmalberga of Temse.[83]
^abMurray, Alison M.; Brinkman, Donald B.; DeMar JR, David G.; Wilson, Gregory P. (March 3, 2020). "Paddlefish and sturgeon (Chondrostei: Acipenseriformes: Polyodontidae and Acipenseridae) from lower Paleocene deposits of Montana, U.S.A.".Journal of Vertebrate Paleontology.40 (2) e1775091.Bibcode:2020JVPal..40E5091M.doi:10.1080/02724634.2020.1775091.ISSN0272-4634.
^Laurin, M.; Reisz, R.R. (1995). "A reevaluation of early amniote phylogeny".Zoological Journal of the Linnean Society.113 (2):165–223.doi:10.1111/j.1096-3642.1995.tb00932.x.
^Sato, Hiroki; Murray, Alison M.; Vernygora, Oksana; Currie, Philip J. (July 4, 2018). "A rare, articulated sturgeon (Chondrostei: Acipenseriformes) from the Upper Cretaceous of Dinosaur Provincial Park, Alberta, Canada".Journal of Vertebrate Paleontology.38 (4): (1)–(15).Bibcode:2018JVPal..3888137S.doi:10.1080/02724634.2018.1488137.ISSN0272-4634.
^abMurray, Alison M.; Nelson, Luke E.; Brinkman, Donald B. (January 2, 2023). "A new sturgeon from the Upper Cretaceous Horseshoe Canyon Formation in central Alberta, Canada".Journal of Vertebrate Paleontology.43 (1) e2232846.Bibcode:2023JVPal..43E2846M.doi:10.1080/02724634.2023.2232846.ISSN0272-4634.
^abBerg, L.S. (1962). Freshwater fishes of the U.S.S.R. and adjacent countries. volume 1, 4th edition. Israel Program for Scientific Translations Ltd., Jerusalem. (Russian version published 1948).
^abZhang, X.; Song, J.; Fan, C.; Guo, H.; Wang, X.; Bleckmann, H. (2012). "Use of electrosense in the feeding behavior of sturgeons".Integrative Zoology.7 (1):74–82.doi:10.1111/j.1749-4877.2011.00272.x.PMID22405450.
^Area, Jam (March 12, 2012)."Reports on past conferences".W.S.C.S., World Sturgeon Conservation Society. RetrievedApril 19, 2019.
^"Sturgeon Spearing".Fond du Lac and the Lake Winnebago Region, Wisconsin, Tourism and Conventions in Fond du Lac, WI. Archived fromthe original on April 19, 2019. RetrievedApril 19, 2019.
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