| Difference in economic characters between two populations, relationship between morphological characters and body weight, molecular phylogeny, and molecular identification were studied by molecular markers, morphological markers and other method.The difference of some productive traits between import and local population of Litopenaeus vannamei was compared during the breeding of the parental shrimp. The quantity of nauplius for average female shrimp per day of import shrimp is more than that of local shrimp, but the total yields of one month is fewer in 28℃temperature. The resistance of local shrimp under the high temperature (≥31℃) is weaker than the import shrimps'. Feeding rates of local parental shrimp decreased at least 50%. The spawn quantity, mating rates and incubation rates also declined rapidly. The fecundity of import shrimp still keeps at limited level. With higher acclimatization to local environment and breeding condition, local shrimps have advantage at mating rates, survival rates and the yield of nauplius in the condition of breeding and climate. Amplified fragment length polymorphism technique (AFLP) was used to amplify 3340 fragments. Fifteen different fragments between local and import strains were successful obtained. Based on local stocks and import strains, considering the excellent trait of local stock of Litopenaeus vannamei with higher acclimatization to local environment compared with import breeded strain of Litopenaeus vannamei, and combining molecular assistant selection with tranditional breeding will provide effective technique to obtain new productive resistant strain of Litopenaeus vanname.54 thirty-day-old portunus trituberculatus were collected for measuring the morphormetric attributes, including the body weight,carapace width,body weight,cheliped length, distance between frontal tooth, distance between lateral tooth. The correlation coefficients among the attributes were calculated,and then path analysis was conducted by taking the body weight as a dependent variable,and other five morphometric attributes as independent variables. The results showed that the carapace width weighted the most(P=0.799) to the body weight is a key effective factor. Cheliped length weighted the lesser (P=0.237) significant direct effect, and the indirect effect with carapace width is main effective factor.The multiple regression equation is: y=-15.616+3.418X1+1.645X3 (y: body weight, X1: carapace width, X3: Cheliped length). This experiment provides a theoretical tool to measure breeding crabs in aquaculture. The partial sequences of CO I and 16S genes were determined from portunus trituberculatus, and partial sequences of CO I was determined from sampled specimen. All homologous partial sequences of CO I and 16 S in Portunidae were collected from GenBank and aligned with the homologous sequences of Portunus trituberculatus. The NJ tree and MP tree were constructed used Kimura 2-parameter model. Homologous sequences (429 bp) of sampled specimen and genus Charybdis were aligned. The results show: The average content of AT is obviously higher than that of GC in both genes. Charybdis is a different group which separated from Portunus, Callinectes and Scylla. Charybdis should be included in subfamily Thalamitinae but not in subfamily Portuninae. Sampled specimen is identified as Charybdis acuta for its genetic distance and R value. The experiments focus on constructing the phylogenetic relationship of portunid crab and identifing of sampled specimen based on fragment of mitochondrion gene. It provides important information for the phylogeny reconstruction and species identification of portunid crab.
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