长江口中华鲟幼鱼对底质的选择

Substrate preference of juvenile Chinese sturgeon Acipenser sinensis captured from Yangtze River estuary

采用单因子实验方法,研究了中华鲟幼鱼对沙(直径<0.2cm)、小砾石(直径1～2cm)、中砾石(直径4～5cm)、大砾石(直径13～15cm)4种底质类型的选择。结果表明:单尾鱼实验时,中华鲟幼鱼(体长283.0mm±18.6mm,体质量86.2g±17.8g,n=30)在4种底质中的时间百分比分别为沙51.50%±21.20%、小砾石20.27%±9.70%、中砾石18.03%±6.17%、大砾石10.20%±11.20%,幼鱼在沙底质中时间明显长于其它3种底质,且差异极显著(P<0.01);多尾鱼实验时,中华鲟幼鱼(体长278.0mm±14.3mm,体质量79.2g±19.6g,n=30)在4种底质中的数量百分比分别为沙46.25%±8.06%、小砾石19.38%±7.72%、中砾石18.75%±7.19%、大砾石15.63%±8.92%,幼鱼在沙质底质中的数量明显高于其它3种底质,且差异极显著(P<0.01);多尾鱼实验中,活动鱼(在水层中游动,不贴底)在4种底质中的数量无显著差异(P>0.05);非活动鱼(贴底游动或静止)在沙底质中的数量显著高于其它3种底质(P<0.01)。单尾鱼(从时间角度)和多尾鱼(从数量角度)实验均表明,中华鲟幼鱼明显选择沙底质。

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 ）.