51813_Sturgeon biodioversity an.PDF

EnvironmentalBiologyofFishes48:209–219,1997.

© 1997KluwerAcademicPublishers. Printed in the Netherlands.

Present status of commercial stocks of sturgeons in the Caspian Sea basin

Raissa P. Khodorevskaya, Galina F. Dovgopol, Olga L. Zhuravleva & Anatolii D. Vlasenko

Caspian Fisheries Research Institute, 1 Savushkina st., Astrakhan 414056,Russia

Received 2.8.1994 Accepted 19.3.1996

Key words:beluga sturgeon,Huso huso,Russian sturgeon,Acipensergueldenstaedtii,stellate sturgeon,Aci-
penserstellatus,population size, artificial propagation, pollution, poaching

Synopsis

Catches for the last 25 years are analyzed for beluga Huso huso, stellate sturgeon A.stellatusand Russian

sturgeonAcipensergueldenstaedtii,which are the three commercially important species of sturgeons found in

the Caspian Sea Basin. Population sizes for generations born between 1961 and 1970 are estimated, and found

to depend on natural reproduction and the number of young fish stocked annually from sturgeon hatcheries

located in the Volga River Delta. A ban on sea fishing from 1962 to 1991 positively impacted the number and

total biomass of commercial stocks. Sturgeon growth rates depend on water levels in the Caspian Sea. In order

to preserve Caspian Sea sturgeon populations, it will be necessary to coordinate efforts of all countries sur-

rounding the Caspian Sea to achieve rational harvests, preserve juveniles, and produce at least 100 million

juveniles annually from hatcheries.

Introduction

Recently, 80 to 90 percent of the world’s sturgeon

catch was taken from the Caspian Sea Basin, mainly

from the Volga River (Barannikova et al. 1995). The

Volga River and Caspian Sea are home to three

commercial species, the beluga (Husohuso,see Pi-

rogovskii et al. 1989), Russian sturgeon (Acipenser

gueldenstaedtii,see Vlasenko et al. 1989a), and stel-

late sturgeon (A.stellatus,see Shubina et al. 1989),

in the Russian (northern) part of this basin. A

fourth commercial species, the Persian sturgeon (A.

persicus,see Vlasenko et al. 1989b), inhabits mostly

the southern (Iranian) part of the Caspian Sea and

the rivers entering into it. Acipenser persicus is not

discussed in this paper because of lack of data.

The natural reproduction of commercial stur-

geon species decreased in the Volga River after the

Volgograd Dam was built between 1958 and 1960

(Figure1).The dam prevents sturgeons from reach-

ing their main spawning grounds. At present, the

Ural River is the only large river entering the north-

ern part of the Caspian Sea in which natural repro-

duction still occurs. Sturgeons no longer use the Ku-

ra and Terek rivers, where spawning previously oc-

curred (Berg 1948). In this paper, we report on pop-

ulation changes in sturgeon stocks in the Caspian

Sea from the early 1960s until 1994 based on data

published in Dyuzhikov (1960), Shilov (1966), Kho-

roshko (1967,1970), VIasenko (1979,1990), Slivka et

al. (1982), Khodorevskaya (1986,1992), Veshchev &

Novikova (1988), Veshchev (1991a, b), Veshchev et

al. (1992), Raspopov (1992, 1993), Dovgopol et al.

(1993), Novikova (1993), Raspopov et al. (1994),

Khodorevskaya et al. (1995), and Levin (1995). Al-

so, the present status of natural reproduction in the

Volga and the Ural rivers is described.