| Chinese shrimp Fenneropenaeus chinensis was one of the important penaeus. However, since 90 times the pond survival and the total output of F. chinensis have been in a low level because of the breakout of many diseases and the deterioration of the cultural environment. Nowadays the reasonable selection breeding program should be built immediately to product seedling with the rapid growth, the strong resistance to disease and adverse. In 2004, Yellow Sea Fisheries Research Institute of Chinese Fishery Sciences Academy (YSFRI) in collaboration with National Fisheries Technical Extension Center (NFTEC) and Akvaforsk Genetic Center (AFGC) initiated"Selective breeding program of Fenneropenaeus chinensis"to demonstrate the advanced selective breeding technology, as applied to develop the Norwegian salmon in Norway and GIFT tilapia in the Philippines. 57 full-sib families (representing 26 paternal half-sib families), which were cultured in the controlled environment were challenged with White Spot Syndrome Virus (WSSV). In this thesis many key questions, i.e. WSSV resistance and the hemolymph analytes, of different populations were tested. And heritability and genetic correlations of many characters were evaluated. Moreover, effects of outbreeding and inbreeding were compared in this study. The following is the results in detail.1 Genetic (co)variation of body weight and resistance to WSSV in young F. chinensisWSSV has been one of the most economically significant pathogens affecting hatchery-reared and wild shrimp world-wide. The survival time, i.e. from all animals contacted virus to their death, and their body weight were recorded in this study. The estimate of heritability (h2±S.E.) for WSSV resistance was 0.10±0.03 when the average body weight of F.Chinensis was 1.56g. Estimated heritability of body weight was 0.18±0.04. Phenotypic correlation between survival time and body weight was different significantly, but genetic correlation between them was not significant. And their correlation coefficients were 0.15±0.00 and 0.08±0.23, respectively. Combining with the results of growth and pond survival ratio, composite breeding value had been computed by the selective index 60:5:35(body: pond survival: resistance to WSSV). The average survival time of all families was 108.83h, which was higher than that of the selected familes 101.27h.2 Comparison resistance to WSSV among the different geographic populations and their hybridization of F. chinensisChinese shrimp is distributed along the coasts of the northern seacoast of China and the Korean Peninsula. According to their migration routes, spawning and overwintering places, F. chinensis are divided into many geographic variety populations. These populations represent potentially different genetic resources in their economical traits important to aquaculture and for their contribution to hybridization breeding programs. To determine their characteristics of resistance to WSSV, mates were made between and within five populations (Rushan population (RS), Qingdao population (QD), Rizhao population (RZ), the wild population in south coast of Korean Peninsula (SKW) and the cultured population in south coast of Korean Peninsula (SKC)) belong to four geographic variety populations, two breeding populations (Huanghai NO.1 (HH1) and Jikang98 (JK98)), and the offspring was reared to 1.51g. The results indicated that the mating combination of SKW♂×JK98♀is best in resistance to WSSV among all populations, and the average survival time is 103.87h post infecting WSSV. QD population is best in resistance to WSSV among intra-population, and the average survival time is 101.73h. RZ population is most sensitive to WSSV in all populations, and the average survival time is 85.53h. The results of this study suggest that hybridization is an important tool to increase resistance to WSSV of cultured shrimps.3 Effects of inbreeding on growth and WSSV resistance of the juvenile Chinese shrimpTo date, few studies had investigated the effects of inbreeding on growth and disease resistance, although inbreeding depression of such traits could play an important role in the evolution and ecology in Chinese shrimp. Effects of inbreeding on body weight and survival time post infection WSSV of juvenile shrimp were quantified on this study. All families were reared under the similar environment conditions, and the differences of growth time between two groups were not significant. The mean body weight and mean survival time of the wild shrimp group were 1.58±0.01g and 100.43±0.68h, and those of the shrimp group with inbreeding coefficient 25% were 1.43±0.04g and 85.84±1.70h, respectively. The differences of body weight and survival time post infection WSSV between two groups were all extremely significant (P<0.01). The difference of phenotypic correlation was not significant (P>0.05) between body weight and WSSV resistance of the wild shrimp group, which is 0.16±0.00, and the inbred shrimp group, which is 0.20±0.00. On this study the estimated inbreeding depression coefficient was -3.80±0.17% for body weight and -5.81±0.11% for survival time post infection WSSV per 10% increase in inbreeding coefficient. Results were consistent with viewpoint that inbreeding could reduce growth and disease resistance. Those highlight the need to maximize the genetic diversity in base population, and consider rate of inbreeding in selective breeding programs and wild resource protection.4 The heritability and genetic correlation of six hemolymph analytes in Chinese shrimpThe modulation of some hemolymph analytes may function as an important indicator of disease resistance, where precise assessment of genetic parameters is crucial to ensure the success of a selective breeding program. In this study, 51 full-sib families (representing 23 paternal half-sib families) were produced and cultured in the controlled conditions, and the genetic parameters, including the heritability, genetic and phenotypic correlation, of total serum protein concentration (PC), hemocyanin concentration (HC), phenoloxidase (PO) activity, superoxide dismutase (SOD) activity, acid phosphatase (ACP) activity and alkaline phosphatase (ALP) activity in the serum of shrimp F. chinensis were investigated. The results showed that when the average body weight of the shrimp was 7.64g, the concentration of six hemolymph analytes were 153.88±1.65mg/ml, 36.04±0.71 U/ml, 165.24±4.93 U/ml, 333.33±2.74 U/ml, 52.51±2.15 U/100ml and 61.68±2.61U/100ml, respectively. And there were not differences between male and female of all immune parameters and their variation coefficients (P>0.05). Evaluations of heritability (h2) were 0.00±0.13, 0.09±0.22, 0.03±0.20, 0.30±0.20, 0.63±0.32 and 0.39±0.25, respectively, for the traits studied. The results also manifested that rearing the families separately in different tanks affected greatly the common cultured condition, indicated by the effects common to full-sibs other than additive genetics as c2, which were 0.10±0.06, 0.20±0.11, 0.21±0.10, 0.00±0.00, 0.02±0.01 and 0.04±0.01 of the six hemolymph analytes, respectively. In this study, the genetic, environmental and phenotypic correlations among the traits were generally positive except those of SOD activity. Results indicated that immunological parameters of Chinese shrimp could be increased by selective breeding programs though heritability of some traits was quite low. Moreover, genetic correlations between the survival time post affecting WSSV of the young prawn and six immunity analytes of the adult were evaluated according to the phenotypic correlations of their breeding values. Results showed that genetic correlations between the survival time and PC, PO and ACP activities were weak positive. The correlative coefficients were 0.093±0.516, 0.058±0.687 and 0.044±0.760, respectively. And genetic correlations between the survival time and HC, SOD and ALP activities were negative. The correlative coefficients were -0.179±0.209, -0.268±0.057 and -0.110±0.441, respectively. These indicated that the correlation between the young resistance-WSSV and the adult immunity was not significant. These had maybe related to the different tested samples, also maybe related to the different expressed mechanism while being affected and the normal grown.5 Heterosis of Hemolymph Analytes of Two Geographic Populations in Chinese ShrimpTo evaluate heterosis of PC, HC, PO, SOD, ACP and ALP activities, mating was produced between and within Yellow and Bo sea (YB) population and southern seacoast of Korean Peninsula (SK) population, and the offspring of 49 families was reared to 8.09g in the controlled environment. Results showed that the content of all hemolymph analytes of SK population was higher than that of YB population, and the differences were significant except of PC and SOD activity. And the immunocompetence of all hybridizations was higher than that in YB♂×YB♀except of HC and SOD activity in YB♂×SK♀. Almost hybridizations had manifested positive heterosis in 6 hemolymph analytes. Heterosis of SK×YB was all positive, and this hybridization was better than YB×SK in HC, PO and ALP activities. The results suggested that the hemolymph analytes of YB and SK populations had many genetic differences, and hybridization was an important tool to increase immune reaction and adverse resistance.6 Inbreeding impacts on some hemato-immunological parameters of F. chinensis, reared under controlled environmentThis study quantified the effects of inbreeding on PC, HC, PO, SOD, ACP and ALP activity of F. rearing in the standard condition. Results showed all traits of shrimp with inbreeding coefficient 25% were lower than those of shrimp without inbreeding, and their difference was highly significant in PO activity, ACP activity and ALP activity (P<0.01). The estimated inbreeding depression coefficients of six traits were -1.74±0.13%, -4.75±0.23%, -10.50±0.31%, 0.62±0.09%,-25.42±0.21% and -21.06±0.30% per 10% increase in inbreeding coefficient, respectively. Results indicated that inbreeding could cause the depression of immunological vigor as that of growth and disease resistance.
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