轮叶黑藻对罗氏沼虾养殖效果影响的现场试验

Field Test on Effect of Aquatic Plant Hydrilla verticillata on Production Performance of Giant Freshwater Prawn Macrobrachium rosenbergii

水温稳定在25℃以上时,在面积0.47~0.62 hm^(2)的4口池塘中放养体长为0.7~0.8 cm的罗氏沼虾(Macrobrachium rosenbergii)"南太湖2号",密度为37.5万尾/hm^(2);同时,截取长约15 cm鲜嫩轮叶黑藻(Hydrilla verticillata)枝条,距离池边5 m扦插,株距约2.5 m,行距约3 m,水草种植区面积约占池塘面积的20%,常规投喂饲养,研究池塘中种植轮叶黑藻对罗氏沼虾的成活率、每公顷产量、饵料系数及养殖水质(氨氮、亚硝酸盐、pH)的影响。1^(#)、2^(#)、3^(#)池塘为平行试验组,4^(#)池塘没有种植轮叶黑藻作对照组。结果显示:试验组罗氏沼虾的成活率比对照组高8%,每公顷池塘产量增加约172.5 kg,饲料系数降低7%。单因素方差分析表明:试验组之间、试验组与对照组之间罗氏沼虾的体长、体质量差异均不显著(P>0.05),但试验组的每公顷养殖效益高于对照组。在罗氏沼虾池塘中种植轮叶黑藻能稳定养殖水体的水质,减少病害发生,提高其成活率、每公顷产量,降低饲料系数,增加养殖效益。

Juvenile giant freshwater prawn(Macrobrachium rosenbergii)“South Taihu Lake 2”with body length of 0.7~0.8 cm were stocked in 4 ponds with an area of 0.47~0.62 hm;at a stocking density of 375,000 ind./hm^(2)at water temperature of above 25℃.At the same time,the about 15 cm long branches of fresh aquatic plant(Hydrilla verticillata)were planted in the ponds at 5 m from the sides,plant spacing about 2.5 m,row spacing about 3 m,with the aquatic plants planting area accounting for about 20%of the pond area,conventional feeding and management to investigate the effects of the plants in the pond on the survival rate,yield per hectare,and food conversion ratio of giant freshwater prawn and culture water quality(ammonia nitrogen,nitrite,pH).Ponds 1^(#),2^(#),and 3^(#)were parallel test groups,and pond 4^(#)was a control pond without Hydrilla verticillata planting.The results showed that there were increase in survival rate by at least 8%,and in yield of per hectare by about 172.5 kg,and decrease in food conversion ratio by 7%in the test groups than those in the control group.SPSS 22.0 software analysis revealed that the higher economic benefits were found in the tests groups than that in the control group,even though without significant differences in body length and body weight of the giant freshwater prawn between the test groups and the control group(P>0.05).Therefore,the aquatic plant planting led to improve survival rate,yield per hectare,reduced the food conversion ratio,and to increase the culture efficiency in giant freshwater prawn ponds,with stable and good water quality of aquaculture water.