51813_Sturgeon biodioversity an.PDF

November) from 1981 through 1993, and in the

spring of 1984. Sturgeons are caught by fishermen in

accordance with our requirements. In the Amur

River, the fishermen use three-layer gill nets (see

Zhang 1985 for description). In the Yangtze River,

sturgeons are taken using row hooks (Deng et al.

1991). Chinese paddlefish are caught incidentally in

gill nets set for copperfish,Coreius heterodom.Our

main sampling location forAcipenser sinensisis in

reaches just below the Gezhouba Dam (Figure 1).

Specimens were measured to the nearest cm (total

length, TL, body length, BL, fork length, FL) and

weighed to the nearest 0.25 kg (body weight, BW).

Since 1983, we have taken Chinese sturgeons,A.

sinensis,from the Yangtze River for artificial propa-

gation and population analysis. We removed the

pectoral fin rays, clavicles and cleithra for age de-

termination, and examined the condition of the go-

nads. Each aging method was read at least twice,

and the results were usually in agreement (Anony-

mous 1988, the age based on annular counts of the

first pectoral fin ray was used in cases of disagree-

ment). Methods used to determine the degree of

gonadal development were taken from Anony-

mous (1988) and Deng et al. (1991). Several speci-

mens in each sample collected since 1982 exhibited

abnormally developed gonads, and we calculated

gonadosomatic indices (GSI = gonadal weight/BW)

to study this. We identified the time and general lo-

cation of spawning for Chinese sturgeon by exam-

Province. Also starting in the 1970s were two long
term investigations of the two species of sturgeons
and the paddlefish in the Yangtze River. The first
project was done between 1972–1975, directed by
the Yangtze River Fisheries Research Institute
(Anonymous 1988). The second project began in
1980, prompted by the construction of Gezhouba
Dam(Fu1985, Ke et al. 1984,1985). These research
programs provide the basis for fisheries manage-
ment and conservation of the three species of Aci-
penseriformes native to the Yangtze River. So far,
A. baerii, A. ruthenus andA. nudiventris from Xing-
jiang Province in northwestern China have hardly
been studied.
In the last thirty years, all stocks of sturgeons de-
clined due to overfishing, construction of hydro-
electric dams, and pollution. The Pearl River pop-
ulation ofA.sinensisand populations ofA.dabrya-
nus andPsephurus gladiusin the Yangtze River
have been severely impacted. This paper reviews
the sturgeons and paddlefish in the Amur and
Yangtze rivers, and discusses conservation strate-
gies.

Materials and methods

Investigations on sturgeons of the Amur River

were conducted from 1978 to 1979. Studies on the

Yangtze River were made each fall (October and

Table 1. Composition of spawning stock of Acipenser schrenckii in the middle reach of the Amur River as related to river location.

(^1) From Heihe to Luobei; see Figure 1.
(^2) FromZhaoxing to Qingdeli; see Figure 1.
SD = standard deviation.
N = number of samples (individuals).