黄河口盐碱地区稻蟹种养模式下中华绒螯蟹适宜放养密度的初探

Preliminary study on the suitable stocking density of Chinese mitten crab(Eriocheir sinensis)under rice-crab co-culture system in the saline-alkaline area of the Yellow River Estuary

为了探索盐碱地稻蟹种养中中华绒螯蟹(Eriocheir sinensis)适宜的放养密度,在黄河口盐碱地进行为期180 d的稻蟹共作试验(雌蟹∶雄蟹=1∶1),研究了不同放养密度(1.50、0.75和0.38只/m2,分别记为D150、D075和D038组)对中华绒螯蟹生长和养殖性能、可食组织系数、生化组成、生理代谢、饵料贡献和经济效益的影响。结果显示:(1)随着养殖密度的降低,中华绒螯蟹的增重率、特定生长率和成活率显著升高,而产量和饵料系数显著降低。(2)各密度组的中华绒螯蟹可食组织系数和总可食率无显著差异。(3)随着养殖密度降低,雌、雄蟹肌肉中粗蛋白含量显著降低,而雌蟹的肝胰腺总脂肪含量显著增加。(4)就生理指标而言,雌蟹肝胰腺中碱性磷酸酶、酸性磷酸酶活力随养殖密度降低而显著升高,而血清中总抗氧化能力和丙二醛含量呈显著下降趋势;类似地,雄蟹肝胰腺中碱性磷酸酶活力在D038组最高,而肝胰腺中丙二醛含量和血清中总抗氧化能力显著降低,在D038组最低。(5)不同放养密度下中华绒螯蟹的第一食物来源均为饲料(39.39%~52.33%),且随养殖密度的降低,食源中饲料占比呈上升趋势,而食源中本底蟹占比呈下降趋势。(6)各组的部分总收入和部分总利润无显著差异,D038组的投资回报率显著高于其他密度组。综上所述,虽高密度组获得最高的产量和收入,但低放养密度组的中华绒螯蟹取得最佳的生长性能和健康状况,且利润和投资回报率最高。因此,在本试验条件下,黄河口盐碱地的稻蟹模式中中华绒螯蟹适宜的放养密度为0.38只/m2。

A 180-day rice-crab co-culture experimental trial(female crab∶male crab=1∶1)was conducted in the saline-alkaline area of the Yellow River Estuary to find the suitable stocking density of Chinese mitten crab(Eriocheir sinensis).The effects of different stocking densities(1.50 ind./m2,0.75 ind./m2 and 0.38 ind./m2,indicated as D150,D075 and D038 groups,respectively)on the growth and culture performance,edible tissue indices,proximate composition,physiological metabolism,contribution of food and economic performance of rice-crab were studied.The results showed that:(1)The weight gain rate(WGR),specific growth rate(SGR)and survival rate(SR)of crab increased significantly with the decrease of stocking density,while the yield and feed conversion rate(FCR)decreased significantly.(2)There was no significant difference in edible tissue index and total edible rate among different stocking density groups,but the gonadosomatic index(GSI),hepatosomatic index(HSI)and total edible yield(TEY)of female crab increased slightly with the decrease of stocking density.(3)With the decrease of stocking density,the contents of crude protein in muscle of females and males decreased significantly,while the contents of crude lipid in hepatopancreas of females increased significantly.(4)In terms of physiological metabolism indices,the activities of alkaline phosphatase(ALP)and acid phosphatase(ACP)in hepatopancreas of females increased significantly with the decrease of stocking density,while total antioxidant capacity(T-AOC)and the contents of malondialdehyde(MDA)in serum decreased significantly.Similarly,ALP activity in hepatopancreas of males was the highest in D038 group,while the contents of MDA in hepatopancreas and TAOC in serum were decreased significantly and minimum value was found in D038 group.(5)The first food source of crabs under different stocking densities was formulated feed(39.39%-52.33%).With the decrease of stocking density,the contribution of feed in food sources was increased,while the contribution of background crabs was decreased.(6)There was no significant difference in partial return and partial gross and the highest profit of each group,whilst the return-on-investment(ROI)of D038 group was significantly higher than that of other density groups.In summary,although the crabs in high-density group had the highest total yield and partial return,the crabs in low stocking density group achieved the best growth performance,health status,profit and ROI.Therefore,under the condition of this experiment,the suitable stocking density of crabs is 0.38 ind./m2 under rice-crab co-culture system in the saline-alkaline area of the Yellow River Estuary.