鳗鲡循环水高密度养殖试验研究

利用室内封闭式循环水养殖系统对欧洲鳗鲡进行高密度养殖试验。结果表明,10 522尾平均体重为55.6 g(18P)的欧洲鳗鲡养殖159 d,成活率达99.7%,总重由584.6 kg增加到1478.0 kg,均重达143.2 g(7.0P),养殖密度从13.0 kg/m3提高到32.8 kg/m3,共投饵1 263.2 kg,鳗鲡增重893.4 kg,饵料效率达70.7%。采用添加营养液和低负载预培养生物膜,使鳗鲡进入系统后水质平稳变化,降低了养殖初期因水质变化剧烈而发生事故的风险。试验阶段养殖池水体氨氮0.03～1.28 mg/L、亚硝态氮0.02～0.75 mg/L、硝态氮1.21～99.60 mg/L,溶氧控制在5～7 mg/L、pH以碳酸氢钠调节稳定在7.0～7.7、水温在23.8～32.4℃间,系统的日换水量在5%内,各水质指标均处于鳗鲡适宜范围内。养殖期间发生2次指环虫病害,利用中草药和无残留药物进行防治,效果良好。利用循环水养殖系统养殖鳗鲡,创造最适的水环境理化条件,在快速生产绿色安全水产品的同时有效节水和减少污水排放。研究亮点:国内首次中试规模(养殖水体45 m3),高密度(32.8 kg/m3)进行了欧洲鳗鲡的循环水养殖试验。养殖试验时间达159 d,鳗鲡达到了商品规格。在中试规模条件下,联合运用预培养生物膜和低负载培养生物膜的方法快速构建了具有稳定硝化功能的生物过滤器。首次比较了不同日换水率条件下,循环水养殖欧洲鳗鲡水体氨氮、亚硝酸盐氮和硝酸盐氮的变化情况。

Research on the cultivating eel in a recirculating aquaculture system

The eel were cultivated in a recirculating aquaculture system(RAS).Result shows that after 159 days cultivating,10 522 eel survival rate was 99.7%.Total weight was increased to 1 478.0 kg from 584.6 kg.Stocking density was increased to 32.8 kg/m3 from 13.0 kg/m3.Total feed was 1 263.2 kg and the eel weight was increased by 893.4 kg.Feed conversion efficiency was 70.7%.By using adding nutrient solution and low stocking density,the water quality was stabilized after the eel stocking in the system.This method would reduce the risk value of preliminary stocking stage.The water quality parameters in the RAS were as follows: the ammonia nitrogen density 0.03-1.28 mg/L,the nitrite nitrogen density 0.02-0.75 mg/L,the nitrate nitrogen density 1.21-99.60 mg/L,DO 5-7 mg/L,pH 7.0-7.7,water temperature 23.8-32.4 ℃.The water exchange of the RAS was less than 5% in 24 hours.The water quality parameters in the RAS were suitable to eel.The eel dactylogyrosis was prevented and cured by using Chinese medicinal herb and nonpersistent pesticide.In conclusion,the RAS can maintain optimum water conditions to culture eel.This is a green,safe and water saving new culture mode.