Effect Evaluation On Stock Enhancement Of Portunus Trituberculatus And Fenneropenaeus Chinensis Based On MtDNA Control Region

Both Portunus trituberculatus and Fenneropenaeus chinensis are very importantfishery resources in China, as well as the mean releasing species of Crustacea. Inpresent study, mitochondrial DNA control region was used to analyze the geneticdiversity of broodstock P. trituberculatus used in stock enhancement, and wildindividuals among recaptured populations were preliminarily excluded based on thecontrol region tags. Movement and growth of F. chinensis in releasing regions werealso studied, while genetic diversity and genetic structure of1broodstock F. chinensispopulation and4recaptured populations were revealed according to the sequences ofcontrol region. Besides, the effectiveness of control region using to estimate stockingeffect of F. chinensis was discussed according to the result. This study aims to offerbasic data and theoretical guidance to found a quantitive assessment system forreleasing actions, and to carry out releasing in a more scientific way. The results of thepresent study were as follows:1. Genetic diversity and population structure of10P. trituberculatus broodstockpopulations were revealed according to536bp mitochondrial control regionsequences. All of the10populations had abundant genetic diversity and similargenetic structure with the wild populations to supplemented, which reflected a goodquality of the germplasm resource. Furthermore, the population history demographyanalysis suggested that P. trituberculatus of the south Bohai sea and north Yellow seahad experienced a demographic or spatial expansion.2. Sequences of mitochondrial control region were used as a genetic tag toevaluate the effect of P. trituberculatus stock enhancement. Among880recapturesfrom Laizhou Bay and open sea of Rushan and Haiyang,49.20%were preliminarilyexcluded as wild individuals through haplotype comparison among all the mothercrabs and recaptured crabs. When haplotype comparison was respectively taken inLaizhou Bay group and Rushan-Haiyang group,50.15%and75.76%recaptures wereexcluded as wild individuals. The high exclusion rate indicated that mitochondrialcontrol region was an effective tag to evaluate releasing effect of P. trituberculatus. But because of common haplotypes, the mother of one specific releasing crab couldnot be identified exactly.3. The movement and growth of F. chinensis in stock regions were carried outthrough follow-up surveys and recaptured surveys in Weihe River and Laizhou Bay.The results reflected that F. chinensis populations moved out from Weihe River toshallow coastal waters after getting a bigger body, and then continued the movementtowards deeper waters along with the growth until they finally left the Laizhou Bay.The relationship of body-length (L) and body-weight (W) could be expressed asW=8.0×10-6L3.0611. Body-length and body-weight von Bertalanffy function were Lt=201.57×[1e-0.016(t-38.48)] and Wt=90.61×[1e-0.016(t-38.48)]3.0611. The growth inflectionpoint occurred when the shrimp was108days old on August15.4. Genetics study of F. chinensis among one broodstock population and4recaptured populations was carried out using sequences of mitochondrial controlregion. It was indicated that the haplotype diversity of F. chinensis was at a high levelwhile the nucleotide diversity got quite a low value. Compared with history recordsrevealed by control region, F. chinensis suffered an obvious decrease in geneticdiversity. Little genetic differentiation was observed in four geographical populations.Besides, the population history demography analysis suggested that F. chinensis hadexperienced a demographic or spatial expansion before19000~35000years.Effectiveness of mitochondrial DNA control region using to estimate stockingeffect of F. chinensis was discussed according to the result of haplotype comparison.890individuals among933recaptures got the same haplotypes with the broodstockshrimp, and more than90%samples of each recaptured population shared commonhaplotypes with the broodstoks. All the above reflected that control region could notidentify releasing shrimp effectively, and did not apply to releasing effect study oflarge-scale F. Chinensis stock enhancement. Uneven quantitative distribution ofrecaptures from different population in common haplotypes partly reflected differentcontribution of mother shrimps to reproduction.