池塘放养密度对施氏鲟幼鱼生长、摄食和肌肉组分的影响

在水温为14 ～ 17℃条件下,将大规格施氏鲟Acipenser schrenckii幼鱼（225.69 g±32.28 g）随机放入9个四边形水泥池（池底面积为18.23 m2）中流水饲养,分别设置5.5、8.0、11.0 kg/m3 3个放养密度组,每组设3个平行,养殖试验共进行70 d,观察并研究放养密度对施氏鲟幼鱼生长、摄食和肌肉组分的影响.结果表明：施氏鲟幼鱼的终末体质量、特定生长率、日增重和摄食率等均随养殖密度的增大而显著降低（P＜0.05）,饲料系数随养殖密度的增大而显著升高（P＜0.05）,密度为8.0 kg/m3的组生长效率最高;肌肉中的粗蛋白质和粗脂肪含量随养殖密度的增大而显著降低（P＜0.05）,雨水分和灰分含量的变化不明显（P＞0.05）;试验期间,水体中的溶解氧浓度随养殖密度的增大显著降低（P＜0.05）,而氨氮和化学耗氧量浓度则随养殖密度的增大而显著升高（P＜0.05）.研究表明,8.0 kg/m3的放养密度更适合大规格施氏鲟幼鱼的养殖,过高的放养密度会对施氏鲟幼鱼生长及其肌肉品质产生不利影响.

Effects and physiological mechanism of stocking density on growth and feeding in juvenile Amur sturgeon Acipenser schrenckii in a pond

The juvenile Amur sturgeon Acipenser schrenckii with body weight of （225.69 ± 32.28） g was reared in nine 18.23 m2 concrete tanks at water temperature of 14-17 ℃ at an initial density of 5.5,8.0 and 11.0 kg/m3 for 70 days to investigate the effects and physiological mechanism of stocking density on growth and feeding.The results showed that there were significant decrease in weight increment,specific growth rate,daily weight gain and food consumption rate and increase in the food conversion ratio in the juveniles with increasing stocking density （P〈0.05）,with the best growth at socking density of 8.0 kg/m3.At the end of the experiment,the crude protein content and crude lipid content were found to be significant decreases（P〈0.05） in muscles,without significant difference in moisture content and ash content （P〉0.05）.During the experiment,a significant decrease in dissolved oxygen level （DO） was observed as the stocking density was increased （P〈0.05）,while the ammonia-nitrogen content and COD were decreased with increasing stocking density （P〈0.05）,indicating that the poor growth derived from high stocking density is contributed to both crowding stress and water deterioration,as well as associated with reductions in food consumption.It is suggested that 8.0 kg/m3 be of suitable stocking density for Amur sturgeon at the size in the experiment.