the Kolyma River upstream from this town, near
the mouth of the Popovka River (1085 km from the
Kolyma River mouth) (Ruban & Akimova 1993).
Sturgeon were caught only in two tributaries of the
Kolyma River, the Korkodon and Ozhogina River
(Dryagin 1948a).the Siberian sturgeon range in the Lena River was
reduced during the last 150 years by 300 km at the
expense of the upper reaches of the river (Figure 1).
The Siberian sturgeon also occurred in some Le-
na River tributaries: the Vitim, Olekma, Aldan, and
Vilyuy rivers (Dryagin 1949, Karantonis et al. 1956,
Kirillov 1972). In the Vitim River they were found
both in the lower (Kirillov 1972) and upper reaches
from the Tsipa River mouth(860 kmupstream from
the Vitim mouth) (Kozhov 1950), and sometimes
even farther upstream, up to the mouth of the Kala-
kanRiver (Kalashnikov 1978). Sturgeon were also
found in the Olekma River (Dryagin 1949, Kirillov
1972). According to my own observation, sturgeon
now migrate upstream the Olekma River approxi-
mately 30 km.
In the Aldan River, sturgeon inhabited the lower
and middle reaches and they were especially abun-
dant in the left tributary, the Amga River (Kirillov
1964). The upper boundaries of the range in the Al-
dan and Amga rivers are not known. According to
information from local people, sturgeon occur in
the Aldan River up to Ust-Mil village (Sokolov et
al. 1986). In the Vilyuy River sturgeon were found
from the mouth up to the Vava River, and they mi-
grated into its tributaries, the Chona, Malaya and
Bolshaya Botuobiya, Tyung, and Markha rivers
(Kirillov 1972). Before the flow regulation in the
late 1960s, it was most abundant in the Chona, Chir-
kuo, and Akhtaranda river mouths. After the im-
poundment of the Vilyuy water reservoir (the Vily-
uyskaya dam was built in 1965), the sturgeon moved
upstream (Kirillov & Solomonov 1979).
In the Yana River, sturgeon occurred from the
delta up to the Verkhoyansk settlement (Kirillov
1972). In the Indigirka River they were caught up-
stream up to the Krest-Maior settlement (850 km
upstream) and some individuals were found up to
the Zashiversk settlement (Kirillov 1953, 1972).
Only single specimens were caught in the Alazeya
River; they migrated to the mouth of its right trib-
Taxonomyandspecies structure of A. baeriiThe first description of the Siberian sturgeon,Aci-
penser baeriiBrandt 1869, was based on specimens
caught in the Ob and Lena rivers (Brandt 1869). Ac-
cording to Chapters31 and 33 of the International
Code of Zoological Nomenclature (1988)^1 , the ini-
tial spelling of this species name should be pre-
served and the widely used nameA. baeri(for in-
stance, Sokolov & Vasilev 1989) is incorrect (Ruban
& Panaiotidi 1994). Nikolskii (1896) described the
sturgeon from the Yenisey River asA. stenorrhyn-
chus,and a form from Lake Baikal as a variety of
this species,A. stenorrhynchusvar.baicalensis.Lat-
er Menshikov (1947) reduced the species,A. stenor-
rhynchus,to the rank of subspecies,A.barerii sternor-
rhynchus.According to Chapter 45 of the Interna-
tional Code of Zoological Nomenclature, the Bai-
kal variety of the sturgeon described by Nikolskii
(1896)should be considered as a subspecies,A. bae-
rii baicalensisNikolsky, 1896 (Ruban & Panaiotidi
1994).
The taxonomic status of another subspecies, the
Yakut sturgeon, A. baerii chatys Dryagin, 1948a, re-
mained unclear until recently (see, for instance, So-
kolov & Vasilev 1989). This form inhabits the rivers
of Yakutiya^2 from the Khatanga River in the west to
the Kolyma River in the east. Many ichthyologists
did not consider this form as a subspecies (Nikolskii
1939, Berg 1948, Andriyashev 1954). Comparative
analysis of morphological characters in large nun-
ber of individualsfrom theYenisey (A. baerii ste-utary, the Bor-Yuryakh River (Dryagin 1933).^1 International Code of Zoological Nomenclature, 1988, 3rd ed.
Nauka Press, Leningrad. 202 pp. (in Russian).(^2) Yakutiya (now sometimes referred to as Saha) is a huge north
central Siberian automomous republic within Russia which is
River on the east and the upper Lena and Aldan rivers at the
south.
In the Kolyma River, sturgeon occurred from the
delta region up to the Seimchan settlement (Drya-
gin 1933), i.e., within 1500 km, but mainly up to the roughIy bounded by the Anabar River on the west, the Kolyma
Verkhnekolmsk settlement (Dryagin 1948a). In
1988–1989 we found that sturgeon were abundant in