Effect Of Stocking Density On Feeding And Growth And Physiological Function Of Juvenile Hybrid Sturgeon

These studies were focused on the subject of juvenile hybrid sturgeon(Acipenserbaerii×Acipenser schrenckii), we have studied the feeding, growth, bloodbiochemistry and immunity changes of hybrid sturgeon whose initial average weightwas （64.4±0.21） g.Fish was grouped four different densitys which is500fish/pond(3.9kg/m3)、800fish/pond (6.3kg/m3)、1100fish/pond (8.7kg/m3)、1400fish/pond (11.0kg/m3).The result is as follows:1. The experiment results showed that juvenile hybrid sturgeon stocking densityaffected the water quality. In the whole experiment, the water temperatureshowed a decreasing trend, pH first rose and then declined. The stocking densitywas negatively correlated with dissolved oxygen. Higher density result inmore low dissolved oxygen.The ammonia nitrogen content and COD significantlyincreased with the increase of stocking density.Results indicated that highstocking density had negative effect on the water quality.2. Higher density resulted in higher mortality, FR and FCE. Final weight, specificgrowth rate (SGR), daily weight gain (DWG) were significantly decreased withthe increase of stocking density（P<0.05）. At the end of the experiment, Moisturecontent and ash content in muscles of fish were increased, but crude proteincontent and Crude lipid content in muscles showed a contrary trend. Theseresults showed that high stocking density had negative influences on mortality,feeding and growth of juvenile hybrid sturgeon.3. The experient studied the effects of high stocking density on Physiological andbiochemical of juvenile hybrid sturgeon. The red blood cells,white blood cellsand blood platelet increased as the density increases，but hemoglobin in differentdensity groups were not significant. In the early of experiment, the Glu and TP ofjuvenile hybrid sturgeon decreased as the density increases, but it was opposite inthe later period of experiment. In the later period of experiment, the glycerin trilaurate showed a decreasing trend as stocking density increase, but ALT andALP had opposite trend.4. The experiment studied the effects of high stocking density on the content ofcortisol， malondialdehyde (MDA) and the activity of superoxidedismutase(SOD),lysozyme of hybrid sturgeon. At the end of the experiment, thecontent of cortisol and MDA increased significantly in high stocking density,while SOD instead. During the whole experiment, lysozyme activityincreased first and then decreased, there was a significant differences in differentdensity groups at10d and80d（P<0.05）.