养殖密度对日本黄姑鱼幼鱼生长及非特异性免疫的影响

Effects of different stocking densities on growth performance and non-specific immunity of juvenile Nibea japonica

以初始体质量(7.67±0.85)g的日本黄姑鱼(Nibea japonica)为实验对象,研究了不同养殖密度对日本黄姑鱼幼鱼生长和非特异性免疫的影响:将其随机分为5组,每缸(200 L)分别放养50、100、150、200、250ind幼鱼,密度分别相当于1.9、3.8、5.7、7.6、9.0 kg·m-3,依次记为G1、G2、G3、G4、G5,养殖时间为30 d。结果显示,G5组幼鱼增重率显著低于其它各组(P<0.05),其成活率也较低。血清溶菌酶活性、皮质醇含量随着养殖密度的增加分别表现出降低、增加的趋势,但各组间差异不显著。不同养殖密度下日本黄姑鱼幼鱼的肾脏、肝脏、肌肉及鳃中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、碱性磷酸酶(AKP)和酸性磷酸酶(ACP)活力有所不同,但总体上没有明显差异。结果表明,本实验条件下,不同实验密度组间日本黄姑鱼幼鱼生长及存活出现了差异,但其非特异性免疫性能并未受到明显影响。

The experiment was conducted to evaluate the effect of stocking densities on growth of juvenile Nibea japonica and growth performance and non-specific immunity for 30 d cultivation with initial body weight （7.67±0.85） g. The fish were randomly divided into 5 groups, and stocked in each cylinder （200 L） for 50, 100, 150, 200, 250 ind per tank, respectively. The densities were equivalent to 1.9 kg·m^-3,3. 8, 5.7,7.6,9.0 kg and marked as G1 ,G2 ,G3 ,CA and GS, respectively. Each group had three replicates. The results showed that the weight gain rate of G5 was significantly lower than that of the other groups （P 〈 0.05 ） and its survival rate was also lower. With the increasing stock density, activity of lysozyme and concentration of cortisol showed an increasing and decreasing trend, respectively, but no significant difference was found among all groups. On the whole, there was no significant difference in the activity of superoxide dismutase （SOD）, catalase （CAT）, alkaline phosphatase （AKP） and acidphosphatase （ACP） in kidney, liver, muscle and gill of juvenile Nibea japonica among the groups. The results indicated that there were differences in growth performance and survival rate among all stock density groups, but the non-specific immunity of juvenile Nibea japonica appeared unaffected by the experimental stocking density under the present condition in this study.