【作者】 孙金辉；

【导师】 沈建忠； 万成炎；

【作者基本信息】 华中农业大学 ， 水生生物学， 2006， 硕士

【摘要】 云龙湖水库位于徐州市郊区，是一座具灌溉、防洪、旅游、水产养殖、城市冲污等多功能的中型水库。为维持水资源的可持续利用，发挥整体综合效益，云龙湖水库今后发展的方向是控制水体富营养化趋势，改善水质。渔业在云龙湖水资源综合利用中占有一定地位，因此，如何避免鱼类放养的不利影响，而利用鱼类的下行效应调节水质，发展生态渔业，便成为持续合理利用水资源的研究课题之一。作者于2004—2005年对云龙湖水库主要放养种类—鲢、鳙生长情况进行了调查分析，作为评价当前放养密度及比例是否合适的间接依据；对水体浮游生物进行了采样调查，通过浮游生物现存量估算了鲢、鳙鱼产潜力及理论放养比例，作为合理放养的参考依据；同时在云龙湖设置了6组原位围隔，分别为单放鳙、鲢鳙比1∶3、1∶1、3∶1、单放鲢和无鱼的对照组，投放密度为20g／m~3，每组设一个平行，意欲通过比较围隔系统内水质理化指标、浮游生物的变化情况及鱼体的生长情况，分析放养鲢、鳙以及不同比例对水质可能造成的影响。为云龙湖合理规划渔业，保护水质，合理开发利用水资源和加强水环境的生态学管理提供科学依据。主要结果如下：1．放养的鲢、鳙在云龙湖中生长较为缓慢，鲢1龄—5龄实测体长、体重分别为22.74cm、0.27kg，28.26cm、0.54kg，33.54cm、0.87kg，39.01cm、1.30kg，41.60cm、1.65kg；鳙2龄—6龄体长、体重分别为29.75cm、0.74kg，34.53cm、1.09kg，40.76cm、1.79kg，52.77cm、3.78kg，58.79cm、4.77kg。养成一般商品规格(鲢750g，鳙1250g)需要3—4年。2．在大库中采集到的浮游植物分属6门28属，平均密度为4.925×10~6ind／L，平均生物量为1.62mg／L；浮游动物分属29属，包括原生动物11属、轮虫10属、枝角类4属、桡足类4属，平均密度为3.04×10~4ind／L，平均生物量2.59mg／L。由此估算鲢鳙鱼产潜力为83639.7kg。其中鲢生产潜力为15603.64kg，鳙生产潜力为68036.06kg。按起水规格鲢750g、鳙1250g计算，鲢、鳙鱼种理论放养比例约为4∶11。3．与没有放养鱼类的对照围隔相比，放养鲢、鳙围隔水体的SD均高于对照组，以鲢、鳙比为1∶1的围隔最高；从TN、TP、COD及Chl-a这4个反映水质营养状况的综合指标来看，实验组围隔水体的富营养化指标均低于对照组，鲢、鳙比例在1∶3和1∶1的实验组富营养化分值较低；放养鲢、鳙围隔内浮游生物个体向小型化发展，易消化种类数减少，不易消化种类数增多，各实验组相比较，鲢、鳙比例在1∶3的围隔浮游生物的生物量相对较低，优势种类数多，数量变化较稳定；各实验组中鲢的生长快于鳙，鱼体总增重量随鲢放养比例的增加而增大。根据调查和试验结果，作者认为，在云龙湖水库放养鲢、鳙，有利于改善水质，但目前鲢、鳙放养密度过高，比例不适合。建议鲢、鳙投放密度控制在20g／m~3以内，鲢、鳙放养比例为1：3，以缩短养殖周期，提高经济效益，有利于改善云龙湖水质。更多还原

【Abstract】 Yunlonghu Reservoir is situated in the suburb of Xuzhou. It is a medium-sized reservoir with multiple functions such as irrigation, flood control of tourism, aquaculture and low flow augmentation. In order to maintain the sustainable exploitation of water resources in the reservoir, it is necessary to curb eutrophication and improve water quality. Because aguaculture has a certain importance at the reservoir, the research question is how to utilize the top-down effects of stocked fishes to control water quality and also to enhance fisheries. In 2004-2005, the research team investigated the growth of the two main stocked fishes, silver carp (Hypophtyalmichthys molitrix) and bighead carp (Aristichthys mobilis).The potential production and the corresponding theoretic stocking ratio of silver carp and bighead carp were estimated based on plankton standing crops to revaluate if the current stocked density and ratio was rational. Twelve in situ exclosures for five experimental treatmnets stocked with bighead carp only, silver carp to bighead carp ratio 1:3, 1:1, 3:1 and silver carp only, respectively, and one control without fish were built. Trophic indics such as water transparency (SD), concentations of N, P, and chlorophyll and plankton composition and biomass and the growth of fish were measured to evaluate the effects of stocking and different ratios of silver carp and bighead carp on the water quality and plankton community structures. Based on research results, proposals were made for developing fisheries in Yunlonghu Reservoir while protecting water quality and rational exploition and integrated management of the water resource. The main results are as follows:1. The growth of both silver carp and bighead carp were relatively slow in Yunlonghu Reservoir. The body length and body weight for age 1-5 of silver carp is 22.74cm and 0.27kg, 28.26cm and 0.54kg, 33.54cm and 0.87kg, 39.01cm and 1.30kg, 41.60cm and 1.65kg, respectively. The body length and body weight for age 2-6 of bighead carp were 29.75cm and 0.74kg, 34.53cm and 1.09kg, 40.76cm and 1.79kg, 52.77cm and 3.78kg, 58.79cm and 4.77kg respectively. The time to reach commercial size for the two fishes (silver carp: 750g, bighead carp: 1250g) was 3-4 years.2. 28 genera of phytoplaknton belong to 6 phylums were collected from Yunlonghu Reservior during the experiment periot. The mean density is 4.925×10~6 ind/L and the biomass was 1.62mg/L. 29 genera of zooplankton were collected, with protozoa 11 genera, 10 genera of rotifer, 4 genera of cladocera and 4 genera of copepoda. The mean density was 3.04×10~4ind/L and the biomass is 2.59mg/L. The potential productivities of silver carp and bighead carp assessed by biomass of plankton was 83639.7kg, in which, 15603.64 kg of silver carp and 68036.06kg of bighead carp. If the catch size of silver carp and bighead carp were 750g and 1250g, the theoretic stocking ratio of silver carp to bighead carp was 4:11.3. Compared with the control, the water SD in the experimental groups stocked with fish, especially in the group with silver carp to bighead carp 1:1, increased. The integrated trophic index including TN, TP, COD and Chla in the experimental enclosures stocked with fish were lower and the scores of trophic index in enclosures stocked with the silver carp to bighead carp ratios of 1:3 and 1:1 were lower than the others. In the enclosures stocked with sliver carp and bighead carp, the size of plankton got smaller and the number of easy-to-be-digested kinds decreaed. In the group with silve carp to bigheae carp 1:3, the biomass decreased mostly remarkedly and the change in biomass and density of plankton was relatively stable and had more dominant species. In all experimental exclosures, silver carp grew faster than bighead carp and the total output of of fish increased with higher ratio of silver carpIn view of the results, we think stocking silver carp and bighead carp in Yunlonghu Reservoir could improve the water quality. The stocking density of silver and bighead in the past, however, was higher and the ratio was not suitable. It was suggested that the appropriate stocking density of silver carp and bighead carp was 20g/m~3 and the ratio was 1:3 for the benefit of shortening the period of culture and raising the income and improving the water quality as well.更多还原