Figure 1. The range of the Siberian sturgeon, Acipenser baerii. Areas where sturgeon are still common, rare, or extinct are indicated by
shading.
Sturgeonbecame cut off fromapproximately Bay tributaries: the Messo-Yakha, Anti-Payuta,
40% of theirspawninggrounds in the ObRiver af- and Ader-Payuta rivers. It inhabits the lower
ter the Novosibirsk hydroelectric dam was con- reachesofthe Pur Riverupto 100 km from the
structed in1957, and in theIrtyshRiver afterbuild- mouth(Chupretov&Slepokurov1979).Historical-
ing the Ust-Kamenogorsk hydroelectric dam in ly, Siberiansturgeonalsooccurred in the Gyda Bay
1952 (Votinov et al.1975). Thesituationbecame and Gyda and Yuribey rivers (Burmakin 1941,
evenworseafter theShulbinsk hydroelectric dam Dryagin1949).
was constructed in1985 on theIrtysh River down- The Shirokaya bay of theYenisey Gulfisthe
streamfrom the Ust-Kamenogorskdam. The mi- northernboundary of theSiberiansturgeons range
gratingform of the sturgeon cannotswim to the in theYeniseyRiverbasin,whileOznachennoe vil-
spawninggroundslocatedupstream. lage was considered as the southern boundary of
In the Taz River, the Siberiansturgeon was found the range beforeconstruction of the hydroelectric
upstreamupto 300 km from the mouth. Italso oc- dam. Thedistancebetween these twogeographic
cursthroughout Taz Bay and in the mouths of Taz points is more than 3100 km (Podlesnyi 1955,1958,