盐度对奥尼罗非鱼仔、稚鱼生长、存活及其消化酶活力的影响

Effects of salinities on growth,survival and digestive enzymes activity of larval hybrid tilapia(Oreochromis niloticus×O.aureus)

研究了不同盐度对奥尼罗非鱼仔、稚鱼生长、存活和消化酶活力的影响。试验设计2、4、6、8、10和纯净淡水0(对照组)共6个盐度梯度组,仔鱼的初始体重0.008±0.001g。结果表明,不同盐度对奥尼罗非鱼仔、稚鱼生长有显著差异(P<0.05),盐度4和6时,仔、稚鱼的生长速度和绝对增重率最高,分别为0.08cm.d-1和0.033g.d-1;盐度10时较低,只有0.06cm.d-1和0.023g.d-1;仔、稚鱼的肥满度介于3.43～3.81,各组之间差异不显著(P>0.05);盐度0～10时,各组存活率介于92.3%～94.7%,幼鱼所占比例介于66.0%～67.3%,各组之间差异不显著(P>0.05);胃蛋白酶和胰蛋白酶活力随盐度升高而降低,均在盐度0时活力最高,10时最低;脂肪酶和淀粉酶活力在盐度4时达到最高,10时最低。根据试验结果,奥尼罗非鱼仔、稚鱼培育的盐度最好控制在4.6左右。

Influences of salinity on growth, survival and digestive enzymes of larval hybrid tilapia were investigated in the present study. Tilapia at an initial average weight of 0. 008 ± 0. 001 g were divided into triplicate groups and were observed at salinities of 2, 4, 6, 8, 10 and freshwater 0. The results showed that the effects of different salinities on tilapia growth were significant （P 〈0.05）, and larval growth was faster when salinities were 4 and 6 with a growth rate of 0. 08 cm·d^-1 and an absolute growth rate of 0. 033 g·d^-1. When the salinity was 10, the growth of larval tilapia was slower; the growth rate was 0. 06 cm·d^-1 and the absolute growth rate was 0. 023 g·d^-1. Since the condition factors of six groups were 3.43 -3.81, each group was not significantly different （P 〉0. 05）. Within the salinities of 0 - 10, the ratio of hybrid tilapia juvenile was 66.0% -67.3% and the survival rate was 92. 3% -94. 7% ; each group did not differ significantly （ P 〉 0. 05 ）. Moreover, the activities of pepsin and trypsin were weakening with increasing salinity, being the highest at salinity of O, while the activities of lipase and amylase were the highest at salinity of 4 and the lowest at 10. The results suggested that the suitable salinity for larval tilapia was about 4. 6.