Abstract: With singlefactor test, the substrate preference of juvenile Chinese sturgeon Acipenser sinensis captured from Yangtze River estuary was examined in laboratory. Four kinds of substrates were tested, i.e., sand (diameter < 0.2 cm), small gravel (diameter 1-2 cm), medium gravel (diameter 4-5 cm), and large gravel (diameter 13-15 cm). The results showed that both the individuals and the groups of juvenileA. sinensis preferred sand significantly, compared with other three substrates. In the individual experiments, the percent of time staying on different substrates was 51.50%±21.20% (sand), 20.27%±9.70% (small gravel), 18.03%±6.17% (medium gravel), and 10.20%±11.20% (large gravel) (n=30), and the time of juvenile A. sinensis staying on sand was significantly longer than on other substrates (P<0.01). In the group experiments, the percent of juvenile A. sinensis number on different substrates were 46.25%±8.06% (sand), 19.38%±7.72% (small gravel), 18.75%±7.19% (medium gravel), and 15.63%±8.92% (large gravel) (n=30), and the amount of juvenile A. sinensis was significantly higher on sand than on the other substrates (P<0.01). The number of inactive fish (relatively motionless on a particular substrate) was significantly more on sand than on the other three substrates (P<0.01), while that of active fish (off the bottom and swimming in water column) had no significant differences on the four substrates (P>0.05).

Key words: Myzus persicae, Erigonidium graminicola, Spatial structure, Models