Environmental Biology of Fishes 48:381-383, 1997.
© 1997 Kluwer Academic Publishers. Printed in the Netherlands.
Threatened fishes ofthe world: Pseudoscaphirhynchusspp.(Acipenseridae)
Vadim J. Birstein
The Sturgeon Society, 331 West 57th Street, Suite 159, New York, NY 10019, U.S.A.
Pseudoscaphirhynchuskaufmanni(Bogdanov,
1874)Common names:Large Amu-Dar shovelnosesturgeon(E),
Grand nez-pelle delAmoudaria(F),Bolshoi Amudarinskii
Lzhelopatonos(R),Sumrai orBeltkumys(Karakalpakian),
ElanLuiryk or TuchkanKuiryk(Uzbek and Turkmen).
Conservation status: Endangered (Uzbek SSR Red Data Book
1983, USSR Red Data Book 1984, Turkmen SSR Red Data Book
1985,1996 IUCN Red List).
Identification:D 25–37, A15–24rays,10–15dorsal scutes,28–40
lateralscutes, and5–11ventral scutes.Veryunusalappearance.
Body is fusiform, thefore part ratherthick.Headends in a broad
spade-likesnout.There are 2–4backward pointing spines on the
tip of the rostrum. Twosimilarspines are located on theupper
side of thehead in front ofvery smalleyes. Thesnout is flattened
on its uppersurface and completelyflat on thelower surface,
wherethere are twopairs of barbels.Headshields arevisible.
The upper lip of thetransversemouth isdivided in the middle,
the lower lip isbroaderthan theupper and isalso slightly divid-
ed. Regularly distributed granulationslyingbetween thescute
rows.Below the dorsal fin base and above theanal finbasethere
are smallflat scutes. All pairedfins and theanal fin are rounded.
Pectoralfinshave averystrong and sharpfirst ray. Thecaudal is
prolonged on itsupperheterocercal lobe in alongfilament. His-
torically, the maximal size of the fish was 75 cm and the 2 kg in weight. In the 1960s, the average size was 37 cm, and 241 g weight. Two forms
were described in the1960s:common and dwarf.Dwarfadults were smallerthan thecommonones andtheir dorsal,anal, andventralfins
were located closer to thetailthan incommon form. In the early1990s, the dwarfform predominated in the population. Dorsumfrom grey
to almostblack,ventrumwhite.William E .Bemis modified thefiguresfromoriginalspublished byNikolskii (1938).
Distribution:Endemic to the Amu Darya River and its tributaries (Central Asia). Historically, P. kaufmanni was distributed along the
riverfrom the upperreaches(Pyandzh River) to the delta.Presently,there are twopopulations: in theVakhshRiver, and the middle
reaches of the AmuDaryaRiver. In the early1990s, only a few individualswererecorded in thelower reaches of the AmuDarya River.
Abundance:No exact estimations. Habitat and ecology: P. kaufmanni live at a depth of 1.0–1.5 m in highly turbulent muddy water. Fish
inhabitshallow-water parts of theriver withfastcurrent,sandy orstony-pebblegrounds.Adults feedmainly on smallfish,with insect
larvae forming the rest of the diet.Reproduction:Takesplace in late March-early May at awater temperature of14–16 C .Males become
mature at 5–7years, and females, at 6–8 years. Intervalsbetweenspawning periodspossiblylast 4–5 years. Fecundity is3127–36558
(common form) or996–1910(dwarfs).Hybridization:Historically, easily hybridized with theotherspecies ofPseudoscaphirhynchus, P.
hermami.Threats:Changes in theenvironmentcaused by the drying out of theAral Sea.Presently, the AmuDaryaRiverdoes notreach
the AralSea.Dams andchannels constructed in the1970s–1980saffected the water regime of the river. Also, thelevel ofwater pollution in
the river is very high.Conservationaction:An internationalrecovery project isplanned byscientists ofKarakalpakstan (a part of
Uzbekistan), Turkmenistan, the United States,and,possibly,Russia.