The grouper Epinephelus awoarea with an initial body weight of (108. 7±4) g were reared in a recirculat-ing system at stocking rate of 10 ,20 ,or 30 kg/m3 for 50 days with triplication to evaluate the effects of stocking den-sity on growth, enzyme activity in liver and gill,and blood physiological indices. The results showed that; 1) There were significantly lower weight gain( WG) and specific growth rate (SGR) at a stocking density of 30 kg/m than at 10 kg/m3 and 20 kg/rn3(P<0. 05), with the maximal food conversion ratio at stocking density of 30 kg/m3. 2) The glutamate-oxaloacetate transaminase (GOT) and glutamate-pyruvate transaminase (GPT) activities in the ser-um and the GPT activities in the liver and gill were found to be increased with the stocking density, with signifi-cantly different between the two groups (P<0.01). 3) There was an increase in the plasma cortisol level as the culture density was increased (P<0.01) , while the count of red blood cells was found to be decrease(P<0. 01). There was significantly lower hemoglobin level in 30 kg/m group than that in other two groups (P<0.05). 4) There was no significant difference in muscle nutrition compositions among three groups ( P>0.05 ) . Conclusively, over high density is unfavorable to the growth of the grouper, and 20 kg/m3 is considered as optimum stocking den-sity in terms of the economical profits.%研究了循环水养殖模式下,不同养殖密度对青石斑鱼Epinephelus awoara生长及肝脏、鳃相关酶活性和血液指标的影响.试验设10、20、30 kg/m3 3个养殖密度组,每组设3个重复,在闭合循环水养殖系统(70 cm×40 cm×40 cm)中养殖初始体质量为(108.7±4)g的青石斑鱼50 d.结果表明:1)10、20 kg/m3养殖密度组青石斑鱼的增重率、特定生长率均高于30 kg/m3密度组(P＜0.05),但30 kg/m3密度组鱼的饲料系数高于其他两组(P＜0.05);2)各组试验鱼血清的谷丙转氨酶(GPT)、谷草转氨酶(GOT)活性及肝脏和鳃的GPT活性均随着养殖密度的增加而明显升高,且组间有极显著性差异(P＜0.01);3)各组试验鱼血清中的皮质醇含量随着养殖密度的增加而明显升高(P＜0.01),而红细胞数则明显减少(P＜0.01),30 kg/m3密度组鱼的血红蛋白含量低于10、20 kg/m3密度组(P＜0.05);4)各组鱼的肌肉营养组成均无显著性差异(P＞0.05).本试验结果表明,养殖密度过高对青石斑鱼生长不利,但从经济收益角度考虑,适宜的养殖密度应为20 kg/m3.
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