1067-4136/02/3305- $27.00 © 2002
Russian Journal of Ecology, Vol. 33, No. 5, 2002, pp. 315–320. Translated from Ekologiya, No. 5, 2002, pp. 335–340.
Original Russian Text Copyright © 2002 by Veshchev.
The Volga is one of a few rivers of the Caspian basin
where stellate sturgeon reproduce under natural condi-
tions. From the mid-1960s to the late 1980s, the num-
bers of spawners that passed upstream of the zone of
commercial ﬁshing averaged 165 200 (Slivka and Pav-
lov, 1982; Dovgopol and Ozeryanskaya, 1997). This
provided for a sufﬁciently high parameters of spawning
in the stellate sturgeon (Veshchev, 1994). In the 1990s,
the Soviet Union and its integrated system of ﬁsh stock
protection ceased to exist, and the economic situation
worsened. This provided a basis for unprecedented
poaching in the Caspian Sea, along ﬁsh migration
routes, and directly on the spawning grounds (Khodor-
, 1994; Raspopov, 1999; Slivka
Ivanov, 2000). The numbers of ﬁsh on the spawning
grounds began to decrease rapidly and eventually
became critically small: 26 800–26 100 ﬁsh in 1997–
., 1998; Khodorevskaya
1999). Thus, a drastic decrease in species reproduction
occurred. The purpose of this study was to estimate the
efﬁciency of reproduction in stellate sturgeon in the
upper, middle, and lower spawning zones of the Volga
and ﬁnd the ways to improve this efﬁciency.
MATERIAL AND METHODS
The material was collected as described previously
, 1993) at nine transects in the lower
reaches of the Volga, from June to August (1979–1998).
The methods of setting cone nets, ﬁshing, and calculat-
ing the absolute numbers of larvae and the coefﬁcients
of commercial return were the same as in the previous
study (Veshchev, 1998). The stages of larval develop-
ment were determined according to Alyavdina (1951).
The mathematical treatment of long-term data by
decades (1979–1988, 1989–1998) was performed using
the STADIA applications software package. Over the
period of studies, 53065 samples were taken and
15710 stellate sturgeon larvae at different developmen-
tal stages were collected.
RESULTS AND DISCUSSION
During the period of observations, conditions
extremely unfavorable for stellate sturgeon spawning
occurred in the low-water years of 1982, 1984, and
1996. In these years, ﬂow discharge in the Volga during
the summer low-water season varied from 39.7 to
, averaging 43.6 km
. The duration of spring
ﬂood was 31 days, the period of water level of above
700 cm at the Svetloyarsk gage was seven days (Table 1).
Hydrologic conditions in the high-water years of
1979, 1981, 1985–1987, 1990–1991, 1993–1995,
1997, and 1998 were different: ﬂow discharge was
1.7 times as great as in low-water years, and the spring
ﬂood was twice as long. Due to high water levels main-
tained for a long time, stellate sturgeon spawned on
ridges located both in the riverbed and in the zone
ﬂooded in spring.
In the years 1980, 1983, 1988, 1989, and 1992, both
ﬂow discharge (54.9 km
) and water levels were inter-
mediate. Although the duration of spring ﬂoods was
fairly long (55 days), the period of the highest water
level was almost the same as in low-water years.
At present, 16 riverbed spawning grounds with a
total area of 248.4 hectares are found in the lower
reaches of the Volga. They may be divided into three
zones. The ﬁrst comprises ﬁve spawning grounds in the
Assessment of Present-Day Reproduction Efficiency
in Stellate Sturgeon
in Different Spawning
Zones of the Lower Volga
P. V. Veshchev
Caspian Research Institute of Fisheries, ul. Savushkina 1, Astrakhan, 414056 Russia
Received August 28, 2001
—Studies performed from 1979 to 1998 provided data on the efﬁciency of natural reproduction of the
in the upper, middle, and lower spawning zones of the Volga. A correlation
between the size of the progeny and environmental factors was revealed. Today, the main factors limiting the
efﬁciency of reproduction in the stellate sturgeon are the numbers of ﬁsh admitted to the spawning grounds
(especially in 1997 and 1998) and water level in the Volga during the summer low-water season. Measures to
support natural reproduction of the stellate sturgeon are proposed.
: reproduction, stellate sturgeon, limiting factors.