mous 1988). Asample of 54 femaleswithstageIV
gonads had:no gonadal fat; GSI11.77–25.95%
(mean 19.11%); and egg diameter 4.0x4.2–4.5 × 5.0
mm. However, since the damming, this situation
has changed. In Table 6 we report data on the devel-
opmental status of theovary for 10 females sampled
in October1984.Only in individual 4 the ovary was
in stage IVofdevelopment. For theother 9 speci-
mens, GSI and egg diameter still had not attained
conditions typical of stage IV even though the gona-
dal fat was exhausted. The shape andcolor ofeggs
weredifferent, and sections showedthat the yolk
was being re-absorbed(Keet al. 1985),sothat the
ovarieswereregressing or degenerating. A similar
phenomenon has beenobserved inothersturgeons
(Kozlovsky1968).In1984,malesalsoexhibited go-
nadal degeneration. Since 1984, we have investigat-
ed further thegonadal degeneration ofspawning
males and females (Figure 6). The absolute number
ofindividualsexhibitinggonadal degeneration va-
ries from year to year but the percentage offish
showing gonadal degenerationhasdecreased from
the 1984 high.
Spawning.–Before the dammingofthe Yangtze
River by Gezhouba Dam in January 1981, spawning
areas forA.sinensisweredistributed in the section
from the upper Yangtze aboveHuling to the lower
Jingsha River below Xingshi, covering atleast 800
km of river length. At least 16 historical spawning
sites are known (Anonymous 1988). However, only
one major spawning site has been found below the
dam.Itis in a narrowarea about 5 kmlong, just be-
low the dam.Aminor spawning site was also found
at Huyiatan, 15 kmbelow thedam, on 23 October
1986 and 14 November 1987. Spawning sites are usu-
allylocated at abend in theriver where the riverFigure 6. Annual variation in gonadal degeneration of the
spawning population of Chinese sturgeon, A. sinensis.bottom consists of gravel or rocks. Typical spawning
sites have a complex substrate, with water depth
ranging from 3 to 40 m, although we believe that
shallow areas are the preferred spawning sites. In
1993, an area 4 to 10 m deep was used for spawning
(Kynard et al. 1995). Spawning occurs in a short pe-
riod from middle of October to middle of Novem-
ber when water temperature is between 15.2–
20.2°C (Anonymous 1988). In general, spawning
occurs twice during the period.
We documented 19 spawning that took place be-Table 6. Reproductive condition of ten female Acipenser sinensis from the Yichang section sampled in October 1984.