Chongqing (Anonymous 1988). The Sichuan Fish-
eries Research Institute (1980) reported a spawning
ground near Yibing as evidenced by the capture of a
female with running eggs on 6 April 1980. The mean
diameter of the eggs, which were fully distended
with water, was 2.8 mm. The spawning site was de-
scribed as 500 m in length, consisting of sand in the
upper part and gravel or cobble in the lower part.
Spawning presumably occurred on 4 April 1980, at a
water temperature between 18.3 and 20.0°C, sur-
face water velocity of 0.72–0.94 m s–1and at a maxi-
mum water depth of about 10 m. They suggested
that the spawning period may be from late March to
early April. We think that natural spawning still ex-
ists in the upper reaches of Yangtze River because
juveniles have been found there since the construc-
tion of Gezhouba Dam (Liu 1992). Spawning in
reaches below Gezhouba Dam must have occurred
from 1983 to 1985, as evidenced by the occurrence of
juveniles in the Yangtze River estuary in the same
period (Zhu & Yu 1987, Yu et al. 1986). However, no
juveniles have been found below the Gezhouba
Dam since 1986, and we think that perhaps these
spawning grounds disappeared after 1986. The total
number of individual Chinese paddlefish recovered
below Gezhouba Dam has been declining since the
middle of the last decade (Figure 3), which suggests
that no recruitment to this population is occurring.
Artificial propagation of Chinese paddlefish has
not been successful. This is in marked contrast to
the ready availability of eggs and embryos of North
American paddlefish,Polyodonspathula(e.g., Be-
mis & Grande 1992). We have difficulties catching
broodstock because of the rarity of Psephurus.
Moreover, captive ripe males and females have
never been available at the same time. We also find
adultPsephurusdifficult to keep in captivity.Conservation efforts.—Before 1983, it was permis-
sible to takePsephurusthroughout the river. Thethe middle reach of the Amur River. tected stations for Chinese sturgeon and paddlefish
Agerange 12 - 20 22 - 40 42 - 44 47 54 were set up along reaches in Hubei and Sichuan
(years) provinces. Fishermen now usually release their in-
N 15 108 6 11 cidental catches. Several attempts to artificially
Percentage 11.5 82.4 4.6 0.75 0.75 spawn paddlefish were unsuccessful, and we haveymous 1988, Lin & Zeng 1987, also see Zhuang etal.
1996 for a map of the Yangtze River). Prior to 1980,
mature individuals only occurred in the upper
reaches of the Yangtze River, juveniles (4 cm TL)
occurred in the Jiangan-Fongdu section of the up-
per Yangtze River, and fingerlings (75 to 250 mm
TL, 5 to 95 g BW) occurred in the Xupu-Chongming
section of the lower Yangtze River (Anonymous
1988). Juveniles ranging 80 to 530 mm TL were
found on the eastern tidal beach of Chongming Is-
land (i.e., the Yangtze estuary) from 1983 to 1985.
Noreport on the population structure of paddlef-
ish is available. According to Lin & Zeng (1987), the
maximum weight is 500 kg. The total length of 17
specimens, which were incidental-catches or car-
casses found just below the Gezhouba Dam from
1981 to 1986, ranged from 148.8 cm to 262 cm TL
(Figure 2). Individuals 182 to 244 cm TL accounted
for 88.2% of this sample. The mean weight of 11 ripe
individuals taken in 1973 from upper reaches of the
Yangtze River was 37.5 kg (Anonymous 1988, aver-
age body weight 26.9 kg, range from 13.9 to 53.5 kg).
The relationship between TL and BW was:BW=
1.577 × 10–7TL3.5250(N = 19, R = 0.9863, FF =
607.702). Ages of spawning individuals ranged from
8 to 12 years. Males with gonads at stage IV account-
ed for 75% of the sample, and the remaining 25%
had testes at stage III (see Anonymous 1988). A sin-
gle female found on 20 November, 1984, was 10
years old, 244 cm TL and 41.5 kg BW, its ovaries
were at stage IV of development. It carried 338 000
eggs with average diameters of 2.45 mm. Yu et al.
(1986) described a female paddlefish found just be-
low the Gezhouba Dam, with gonads at stage IV
and egg diameters ranging from 2.8 to 3.8 mm.
Reproduction and present status. —The spawning
grounds for Chinese paddlefish are unknown. They
are probably scattered and limited to reaches aboveTable4.Age composition of spawning stock ofHusodauricusin species has been fully protected since 1983, and pro-