1963). It was assumed that the non-migrating form
lived in the Yenisey River over 2300 km from the
Oznachennoe village to the city of Igarka (Podles-
nyi 1955). Sturgeon did not, apparently, migrate up-
stream from the Yartsevo village (1759 km from the
river mouth) (Podlesnyi 1955) or the town of Yeni-
seysk (Podlesnyi1958). They were caught rarely up-
stream from the city of Krasnoyarsk (2454 km from
the Yenisey mouth) (Podlesnyi 1963). In the past,
sturgeon migrated to the near-mouth parts of trib-
utaries of the middle Yenisey River, the Tuba and
Abakan rivers, but now, according to the informa-
tion received from local people, it is completely ab-
sent upstream from the Krasnoyarsk hydroelectric
dam (built in 1967). Therefore, the sturgeon range
in the Yenisey River has been reduced, and its
southern boundary moved tothe northby 500–600
km.
In the largeYeniseytributaries,such as theAnga-
ra, Podkamennaya andNizhnyaya Tunguskarivers,
thereweresmall populations of non-migrating stur-
geon(Podlesnyi 1955,1958);theupperboundary of
its range in the two latterrivers has notbeendeter-
mined. Thesturgeonoccurredalso in the lowertrib-
utaries of theNizhnyaya TunguskaRiver, theKo-
chechum,Vivi,Kuchumdek, and Tutokchanrivers
(Dryagin1949). It wasalsofound in theKureika
River in the19thcentury (Tretyakov 1869).
In the AngaraRiver thesturgeoninhabited an
areafromthe mouth up to theestuary of the Belaya
River (Dryagin 1949).Also,juvenileswerecaught
several times near the Angara River source and
near the city ofIrkutsk(Yegorov1941,1961). The
sturgeon occurred in the Angara River tributaries,
the Taseyeva(and its tributary Chuna) and Oka riv-
ers (Yegorov1963).
In LakeBaikal, Siberiansturgeonweremost
abundant in the area near the delta of theSelenga
River, aswell as in theBarguzinskii and Chivyrkuis-
kii bays.Sturgeonmovedfrom these mainhabitat
regions along the coast in the shallow-waterzone of
the lake to the mouths ofthe large tributaries of the
lake,fromwhichthey migrated intothese tributar-
ies. They were rare in the northern part of Lake Bai-
kal at the mouth of theVerkhnyayaAngara and
Kichera rivers. They migrated into the Selenga Riv-
er up to 1000 km, including its tributaries Chikoy
and Orhon rivers (Yegorov 1961), as well as into the
Tula andDelger-Murenrivers(Sokolov&Shatu-
novsky 1983). Also, they migrated into the Barguzin
Rivermore than 300 km upstream, and into the
VerkhnyayaAngaraRiver, up to100–150 km (Ye-
gorov1961).Siberiansturgeonwerealsofound in
smaller tributaries such as theTurkaRiver.
In the PyasinaRiverSiberiansturgeonwererath-
er rare(Dryagin1949).They were not caught in the
Pyasina Bay (Ostroumov 1937), but were found in
the Pyasina basinlakes, theLama and Melkoe (Be-
lykh1940,Logashov1940).
In the Khatanga River basinsturgeon were found
both in the estuary (Tretyakov 1869, Berg 1926) and
upstreamfromthe Khatanga River to the con-
fluence ofthe Kheta andKotuy rivers, whichform
the KhatangaRiver. Inthe Kheta River, they were
caught over 460 kmfrom themouth toVolochanka
village,althoughtheirmainhabitat inthis river is
from themouth to 350 km upstream(Lukyanchi-
kov 1967).Sometimes sturgeonwerenoticed in the
flood plainlakes of the Kotuy River, where they mi-
gratedwith thespringwater. Sturgeonwerefound
in the middle and low reaches of theAnabarRiver
(Kirillov1972).
In the Olenek River the sturgeon was ararefish
(Kirillov 1972). Usually itmigratedupstream up to
the Pur River mouthand,exceptionally, to the
mouth of theChemudakh brooklocated1020 km
from therivermouth.
Siberiansturgeoninhabited theLena Riverbasin
up from therivermouth and theNeyelova Bay
(Dryagin1948a,1949).Duringhigh-water years
they migrated into the Tiksi Bay andcoastal regions
of the Bulunkan andSogobays (Kirillov1950).
Within theLenaRiver,sturgeonmoved up to the
Korshunovovillage(Borisov1928,Dryagin1933,
1949, Karantonis et al. 1956, Dormidontov 1963, Ki-
rillov 1972), and the total length of its range was ap-
proximately3300 km inthisriver. Thetown of Ki-
rensk is considered as the southern boundary ofthe
sturgeon range in the Lena River.Earlier, in the
1840s, the southern boundary was at Makaryevskoe
villagelocated upstream from thetown ofKirensk
(Maak1886). A t the end of the19thcentury,stur-
geonalsoinhabited therighttributary of the Lena
River, the Kirenga River (Borisov 1928). Therefore,