Environmental Engineering Reference
In-Depth Information
Water temperature is an essential factor for hatching; flow velocity influences the distribution of eggs
and their cohesiveness on the river bed. Excessive suspended sediment concentration may cause sturgeon
eggs to debond, which then affects fertilization and hatching. According to Chang (1999), 90% of sturgeon
eggs suffer predation. The data sources used to develop the SIS are listed in Table 10.8, and the SI curves
are shown in Fig. 10.46. The value of V 10 (the ratio of estimated brood sturgeon to eggs-predatory fish) is
not shown in the figure, because it depends on the physical conditions and the number of the eggs-
predatory fish in the previous year. In the modeling the value of V 10 is assumed equal to 1.0, i.e. the amount
of eggs-predatory fish is the lowest in the record.
T able 10.8
Eco-factors for Chinese Sturgeon (after Yi et al., 2007)
Variables
Eco-factors
Results of previous research
The Chinese sturgeon can survive temperatures between 0-37 ć ; 13-25 ć is suitable
for growth, and 20-22 ć is optimum. The sturgeon becomes anorexic and stops
growing when temperatures fall to 9-6 ć (NERCITA, 2004a). Research results indicate
that the Chinese sturgeon grows well under a wide range of temperatures; feeding has
been recorded from 8-29.1 ć (Guo and Lian, 2001). Yan (2003) found that Chinese
sturgeon prefer tepid water, anorexia results and growth almost stops when temperatures
are < 6 ć and > 28 ć , growth rate slows when temperatures are near 10 ć . 18-25 ć is
an optimum range for growth; sturgeon will die when temperature is >35 ć . The
optimum temperature for juvenile sturgeon is 22-25 ć (Zhang, 1998).
Water
temperature
(adults and
juveniles)
V 1
The Chinese sturgeon is distributed in areas with 9.3-40 m water depth; 90% of
individuals are distributed at depths from 11-30 m; 11 Chinese sturgeons detected in the
Yanzhiba to Gulaobei reach were distributed at depths from 9-19 m (Wei, 2005).
Water depth
(adults)
V 2
Juvenile and adult Chinese sturgeons have similar substrate choices as with short-nose
sturgeon in the US. Experiments show that juvenile short-nose sturgeon prefer habitat in
sand-mud substrate or gravel substrate (Pottle and Dadswell, 1979). Chinese sturgeon
prefer to cruise along river channels with deep trenches and sandy dunes, and are fond of
resting in pools, backwaters, and places varied terrain (Guo and Lian, 2001).
Substrate
(adults)
V 3
The spawning temperature for sturgeon is 17.0-20.0 ć ; spawning will stop when
temperature < l6.5 ć (Hu et al., 1992). The average temperature in the reaches downstream
of the Gezhouba Dam during the sturgeon spawning period is 15.8-20.7 ć . About 79.31%
of fish are spread in the range of 17.5-19.5 ć ; the average temperature of the original
spawning sites in the upper reaches of the Yangtze River is 17.0-20.2 ć . Therefore, the
suitable spawning temperature for Chinese sturgeon is 17.0-20.0 ć (Wei, 2005).
Spawning occurs when temperature is 15.3-20.5 ć ; the suitable range is 17.0- 20.0 ć ,
and the optimum is 18.0-20.0 ć (Yang et al., 2007).
Water
temperature
(spawning)
V 4
More than 20 years' of monitoring indicates that the length of new spawning sites is
about 30 km from the tail water area of Gezhouba Dam to Gulabei, with 10-15 m water
depth (Guo and Lian, 2001). The “stable spawning site of Chinese sturgeon” determined
by Deng et al. (1991) has a water depth in a range from 4-10 m.
Water depth
(spawning)
V 5
Gravel and pebbles are present in Chinese sturgeon spawning sites of (Li, 1999). The
substrate of new spawning sites are composed of sand, grave with sand, gravel and stone,
and gradually coarsen from left to right bank (Hu et al., 1992). The substrate of the
original centralized spawning sites of Chinese sturgeon was mainly composed of stones
and gravels (Xing, 2003).
Substrate
(spawning
and hatching)
V 6
The suitable temperature for hatching is 16-22 ć , the optimum is 17-21 ć . The hatching
rate decreases when at temperature < 16 ć ; deformity rate increases at temperature > 23 ć .
The temperature should be stable when zoosperms are hatching, abnormal fetation or
death will occur with even small fluctuations in temperature of 3-5 ć (NERCITA,
2004b). Water temperature for cultivating fries should be between 12-29 ć ; the most
suitable temperature is 16-24 ć (Wang et al., 2002).
Water
temperature
(hatching)
V 7
Search WWH ::




Custom Search