Comparative Study On Two Cultivation Models Of Macrobrachium Nipponense

Deterioration of water quality and over-fishing have led to a sharp decline in the amount of wild resources of Macrobrachium nipponenses.Artificial stock enhancement has effectively improved this situation.However,in the process of proliferation and release stock enhancement,there has always been a problem of larvae shortage caused by its low emergence rate of Macrobrachium nipponenses.By comparison of production process including breeding facilities,the selection of parent shrimp,larval survival rate,water quality control,bait selection and feeding,disease control and nursery effects of cement pond breeding model and mud pond breeding model in Biayngdian lake and Hengshuihu lake,this thesis aims to find key technologies that affect the effects of two types of breeding model.The main results are as follows:The investigation of artificial breeding and semi-artificial breeding processes in the Baiyangdian found that during the larval development,the body length of each larvae development stage in the in mud ponds was greater than that in the cement ponds,and there were significant differences in the ? and ? stages.Larvae Survival rates from II to III,from IV to V,and from IX to post larvae in mud ponds decreased significantly compared with other periods.It could be seen that the II-V stage and IX-postlarval stage were the key nodes of artificial breeding of Macrobrachium nipponense.The average emergence rate in mud ponds(32%)was much higher than that in cement ponds(17.7%).The reason could be that the larvae in the mud ponds are mainly feeding natural baits,while in the cement pond are mainly feeding artificialfeed and the nutrient in the artificial feed could not meet the growth of the larvae;The change of living habits of postlarvae wass the direct reason to reduce the emergence rate in cement ponds.Experiments had shown that adding attachments to the cement pond could significantly improve the emergence rate of IX to postlarvae.The presence of aquatic plants in mud ponds wass an important reason for its high emergence rate.The emergence rate of Hengshui Lake in mud pond(29.9%)was greater than that incement ponds(24.9%),while the emergence rate of Hengshui Lake in cement ponds was higher than that of Baiyangdian Lake,and the difference in mud pond nursery model is insignificant.The reason was differences in t the choice and method of feed.By comparing the two nursery breeding models between Baiyangdian Lake and Hengshui Lake,the key optimization techniques are as follows:Cement pond artificial breding model: 1)Directly put the parent shrimp into the nursery pond and timely move off broodstockto reduce the mortality of the parent shrimp,and increase the hatching stage larvae output rate 2)To ensure the synchronization of shrimp larvae in each stages.3)Select suitable feed for satisfying nutrition of the juveniles and supplement the artificially cultivated natural bait.4)The behavioral changes of from IX to postlarvae is conducive to the survival rate of postlarvae by increasing attachments in the breeding ponds.5)Breeding in the cement pond is likely to cause water quality deterioration.However,strengthening water quality monitoring,such as and exchanging water,spraying EM and other microbial agents appropriately can regulate water quality.Semi-artificial nursery model of mud pond: 1)Water quality regulation.During the process of breeding,put in sediment and water quality improver,regularly exchange the pond water,to ncrease the survival rate of the postlarvae.2)aquatic plants density.In the process of breeding,the density of aquatic palnts should be maintained at about 30% to ensure the nutritional requirements of artificial bait and provide attachments for postlarvae.3)Feed optimization.Spay a certain amount of artificial bait in the early stage to improve the survival rate of larvae from the IIto the III stage.