鲻混养密度与网箱围隔对鱼虾混养效果和水质的影响

【目的】研究鲻鱼混养密度与网箱围隔对鱼虾混养效果和水质的影响,为今后发展推广鱼虾混养模式提供科学依据。【方法】分别在3.2 m×3.2 m的室内水泥池放养800尾虾苗（处理I）、800尾虾苗＋1.0 kg鲻鱼（处理II）、800尾虾苗＋2.0 kg鲻鱼（处理III）、800尾虾苗＋3.0 kg鲻鱼（处理IV）、800尾虾苗＋2.0 kg鲻鱼（处理V）,处理V用网箱将鲻鱼隔离在网内而对虾可通过,探讨凡纳滨对虾与鲻鱼混养对鱼虾生长、饲料效率、能量效率和蛋白质效率及水质的影响。【结果】收获时,凡纳滨对虾的体长、体重、产量、增重率、特定生长率及鲻鱼的体重、增重率、体重特定生长率均随鲻鱼混养密度增加而呈下降趋势;采用网箱围隔相对其他混养处理能够明显改善对虾的生长状况,但仍显著低于单养对虾处理（P〉0.05,下同）。【结论】凡纳滨对虾混养鲻鱼能有效提高饵料利用率,但由于鲻鱼抢食虾料而影响对虾生长;采用网箱围隔混养在一定程度上能改善对虾生长,却未能提高饵料利用率。因此,凡纳滨对虾混养鲻鱼时,二者间的合理放养密度有待下一步探究。

Effects of gray mullet density and net enclosure on polyculture and water quality

【Objective】The effects of gray mullet density and net enclosure on polyculture and water quality were studied to provide references for extending the polyculture mode of fish and shrimp. 【Method】The study was conducted in 3.2 m×3.2 m indoor cement tanks by stocking 800 shrimps postlarvae and 0kg fingerlings（I）, 800 shrimps postlarvae with 1kg fingerlings（II）, 800 shrimps postlarvae with 2 kg fingerlings（III）, 800 shrimps postlarvae with 3 kg fingerlings（IV） and 800 shrimps postlarvae with 2 kg fingerlings in net（V）. Fish were in the net and shrimp could enter or get away from net in treatment V. 【Result】The harvested shrimp length,weight and production,weight gain rate and specific growth rate of shrimp, and the weight, weight gain rate, specific growth rate of fish all decreased with the increase of gray mullet density. The growth of shrimp in treatment V were obviously improved than that of other polyculture modes, but significantly lower than that of monoculture（P〈0.05, the same hereinafter）. In polyculture treatment II-IV,the feed coefficient was significantly lower than that of monoculture（P〈0.05, the same hereinafter）,and the feed conversion efficiency, protein efficiency and energy efficiency were effectively improved. Compared with monoculture, the utilization of feed in treatments V was not improved significantly（P〉0.05, the same hereinafter）. The whole trend of water changes was basically identical with monoculture, except some individual water indexes presented obvious changes in different periods. 【Conclusion】The utilization ratio of food can be effectively improved by adding Mugil cephalus in Litopenaeus vannamei culture, but the growth of shrimp is influenced because of fish’s snatching behavior.The growth of shrimp can also be improved using net enclosure, but the utilization ratio of food remains the same.Therefore, reasonable densities of fish and shrimp require further investigation.