不同草鱼池塘混养系统结构优化的实验研究

研究采用陆基围隔实验法,对草鱼(Ctenopharyngodon idellus)、鲢鱼(Hypophythalmichthys molitrix)、鲤鱼(Cyprinus carpio)和凡纳滨对虾(Litopenaeus vannamei)不同混养系统的养殖产量、投入产出比、氮磷利用率和综合养殖效果进行了研究。实验设置6个处理组,分别为草鱼单养(G)、草鱼和鲢鱼二元混养(GS)、草鱼、鲢鱼和鲤鱼按照不同比例放养的三元混养(GSC1和GSC2)和草鱼、鲢鱼和凡纳滨对虾按照不同比例放养的三元混养(GSL1和GSL2)。研究结果表明,各处理组总产量在770480—11492.50 kg/hm2之间;饲料系数在1.00—1.38之间,以GSC1最低,各处理组之间差异显著(P<0.05)。N、P总相对利用率在2.01—7.37之间,以GSL2最高,G最低;投入产出比在1:1.41—1:2.12之间,以GSL2最高,G最低;综合效果指标在0.59—1.39之间,以GSL2最高,G最小。研究结果表明,混养组能显著提高养殖系统的产量,降低饲料系数,提高N、P利用率,从而有效提高草鱼养殖的经济效益和生态效益。

AN EXPERIMENTAL STUDY ON STRUCTURE OPTIMIZATION FOR POLYCULTURE OF GRASS CARP WITH DIFFERENT SPECIES

This research was designed to find out the best polyculture mode of grass carp ponds.The outputs,total cost vs gross receipt and synthetic efficiency index of different ecosystems,in which Ctenopharyngodon idellus,Hypophythalmichthys molitrix,Cyprinus carpio and Litopenaeus vannamei cultured in different mono-and poly-culture treatments,were studied in land-based enclosures.There were six treatments: grass carp treatment(G);grass carp and silver carp treatment(GS);two treatments stocked grass carp,silver carp and common carp with different proportion(GSC1 and GSC2);two treatments stocked grass carp,silver carp and vannamei with different proportion(GSL1 and GSL2).The results indicated that the water quality objectives of poly-culture were better than G treatment;the Chl.a of G treatments were higher than other treatments.The results of single factor analysis of variance and Duncan multiple comparison analysis showed that the difference among each treatment was significant(P<0.05).The net output of grass carp ranged from 3738.09 kg/hm2 to 6548.30 kg/hm2 and the survival rates ranged from 98.67% to 100%;the net output of silver carp ranged from 1097.28 kg/hm2 to 3391.84 kg/hm2 and the survival rates ranged from 87.88% to 100%;the net output of common carp ranged from 1975.51 kg/hm2 to 2828.57 kg/hm2 and the survival rates were 100% totally;the net output of shrimp ranged from 718.80 kg/hm2 to 958.10 kg/hm2and the survival rates ranged from 40.96% to 47.17%;the total outputs of ecosystem ranged from 7704.80 kg/hm2 to 11492.50 kg/hm2;the net outputs ranged from 6548.30 kg/hm2 to 9958.50 kg/hm2,the G treatment was the lowest and GSC1 treatment was the highest,and the difference between each treatment was significant(P<0.05).The feed coefficient ranged from 1.00 to 1.38,GSC1 treatment was the lowest and GSL2 treatment was the highest,and the difference between each treatment was significantly(P<0.05).The total N input ranged from 372.56 kg/hm2 to 421.90 kg/hm2;the total P input ranged from 34.40 kg/hm2 to 38.96 kg/hm2;the total relative utilization rates of N and P ranged from 2.01 to 7.37,G treatment was the lowest and GSL2 treatment was the highest,and the difference between each treatment was significant(P<0.05).The total costs of each treatment were ranged from 4.77×104$/hm2 to 6.15×104$/hm2;the total benefits were ranged from 7.32×104$/hm2 to 12.61×104$/ hm2;the total cost vs gross receipt ranged from 1:1.41 to 1:2.12,the G treatment was the lowest and the GSL2 treatment was the highest,the difference between each treatment was significant(P<0.05).The synthetic efficiency index ranged from 0.59 to 1.39,the G treatment was the lowest and the GSL2 treatment was the highest,and the difference between each treatment was significant(P<0.05).The results showed that poly-culture could obviously improve outputs of ecosystem,reduce feed coefficient,increase utilization rates of N and P,and finally raise economic and ecological benefits of ecosystem.The conclusion could be made that the GSC1 and GSL2 treatments were better than other treatments,and the stocking density of GSC1 as that: grass carp,69.39 g/m2,silver carp,20.75 g/m2and common carp,54.08 g/m2;the stocking density of GSL2 as that: grass carp,69.39 g/m2,silver carp 56.46 g/m2and vannamei,14.80 g/m2.