Parent-offspring relationship recognition based on SSR and mtDNA confirmed resource supplement effect of Fenneropenaeus chinensis release

The resource of Fenneropenaeus chinensis has declined sharply due to excessive fishing intensity,ecological changes and diseases.In order to supplement the fishing yield and restore resources of F.chinensis,the relevant authorities have carried out the activities of stock enhancement and releasing.It can increase biomass and recover resources.However,compared with increasing biomass,there were still few reports on its effect on the recovery of resources.Resource recovery is a process related to whether the released individuals can form a reproductive population.Up to now,there has been a lack of evidence whether the released F.chinensis can complete the entire life history,and form reproduction population.In this study,gravid female shrimp after spawning migration were captured from coastal waters of Haiyang,Qingdao,and Yellow Sea.After identifying parentage relationships using simple sequence repeat(SSR)and mtDNA haplotype,it was finally confirmed that there were eight released individuals in the recapture samples.It was confirmed for the first time that at least part of the released F.chinensis can complete overwintering and reproductive migration,and maintain the migration habits as their wild counterparts.Therefore,we infered that the released shrimp can reproduce under natural conditions,these F.chinensis can form reproductive populations theoretically if without human intervention.These results indicated that enhancenment and release activities have a positive effect on resource recovery.

Molecular identification and biochemical characteristics of a delta class glutathione S-transferase gene(FcδGST)from Chinese shrimp Fenneropenaeus chinensis

Glutathione S-transferases(GSTs)are a superfamily of multifunction enzymes involved in the regulation of redox homeostasis and innate immune responses against various pathogenic infections in marine invertebrates.In the present study,a delta class GST gene(designated as FcδGST)was cloned from Fenneropenaeus chinensis using rapid amplification of c DNA ends(RACE)technology.The complete cDNA sequence of FcδGST was 780 bp in length,which includes a 27-bp 5′non-coding region(UTR),a 117-bp 3′UTR,a 636-bp open reading frame(ORF),and a polyadenylate signal site(AATAAA)presented at the upstream of poly A tail.The FcδGST gene encoded 211 amino acids peptide,including a GST_N domain and a GST_C domain,and exhibited high similarity with previously reported delta GSTs.The predicted molecular mass of FcδGST protein was 23.39 kDa,and its theoretical isoelectric point(pI)was 5.34.The FcδGST mRNA transcripts were ubiquitously expressed in all the tested tissues,with the highest expression level in hemocytes and hepatopancreas.During the stimulation of Vibrio anguillarum or white spot syndrome virus(WSSV),the m RNA expression of FcδGST in hemocytes and hepatopancreas revealed significant up-regulation.The purified recombinant FcδGST protein(designated as rFcδGST)exhibited specific catalytic activity against 1-chloro-2,4-dinitrobenzene(CDNB)substrate with relatively low stable enzymatic activities.These results indicated that FcδGST was a fragile but typical novel delta class GST member and potentially involved in the innate immune responses of F.chinensis.

Effects of Salinity and Dietary Chinese Herbal Medicine on Survival and Growth of Juvenile Fenneropenaeus chinensis

[Objective] The aim of this study was to provide theoretical basis for the large-scale breeding of Fenneropenaeus chinensis as well as the promotion of Chinese herbal medicine.[Method] The experiment was conducted to determine the effects of salinity（12‰,20‰ and 28‰）and dietary Chinese herbal medicine（CHM：0%,1%,2% and 4%）on survival and growth of juvenile F.chinensis with the average initial wet body weight of 0.027±0.005 g.The experiment lasted for 5 weeks.[Result] The survival rate,specific growth rate,food consumption and apparent digestibility coefficient was increased with CHM level increasing;when attained the critical value,the survival rate,specific growth rate,food consumption and apparent digestibility coefficient decreased with CHM level increasing.Food conversion ratio decreased with CHM level increasing,and then it increased after attained the critical value.At each CHM level,the survival rate,specific growth rate,food consumption and apparent digestibility coefficient were highest at salinity of 20‰,while food conversion ratio was lowest at salinity 20‰.[Conclusion] Salinity and CHM had a significant effect on growth of F.chinensis,which should be paid more attention in the breeding.

Estimates of Heritability and Genetic Correlations for Growth Traits in Chinese Shrimp Fenneropenaeus chinensis

[Objective] The aim was to estimate the heritability and genetic correlations of growth traits of Chinese shrimp Fenneropenaeus chinensis so as to provide basis and technical parameters for the breeding and selecting of Chinese shrimp.[Method] 51 full-sib families（including 35 half-sib families）of the Chinese shrimp F.chinensis were obtained by artificial insemination.Four growth traits of these families were measured,including body length,cephalothorax length,abdorminal segment length and body weight.According to quantitative genetics theory,the heritability of each growth trait,genetic and phenotypic correlation among these traits was statistically studied.[Result] The heritability was 0.36-0.51 for body length,0.14-0.24 for cephalothorax length,0.25-0.50 for abdominal segment length,and 0.04-0.29 for body weight.High and positive genetic correlations were obtained among growth traits.The genetic correlation between body weight and abdominal segment length was the highest（0.92）,followed by body length and abdominal segment length（0.91）,body length and body weight（0.88）,body weight and cephalothorax length（0.87）,abdominal segment length and cephalothorax length（0.86）,while the genetic correlation between body length and cephalothorax length was the lowest（0.83）.[Conclusion] The phenotypic correlation of body length,cephalothorax length,abdorminal segment length and body weight of Chinese shrimp F.chinensis were from 0.80 to 0.90 with extremely significant difference（P0.01）among the four growth traits by t-test.

Effects of salinity fluctuation in different ranges on the intermolt period and growth of juvenile Fenneropenaeus chinensis

Experiments were conducted to examine the effects of salinity fluctuation on the intermolt period and growth of Fenneropenaeus chi- nensis with an initial body weight of (0.553 2±0.000 1)g (mean plus or minus SE). The salinity (S0) of the control treatment is 30 throughout the experiment, while the treatments S2, S4, S7 and S10 are subjected to different salinity fluctuations, and the ranges are 2, 4, 7 and 10, respectively. After a 30-day feeding trial, the longest and the shortest intermolt periods of the shrimp occur under Treatments S10 and S2, respectively (difference 37.14%). The special growth rates (SGR) of the shrimp under the five treatments are ranked as S7> S4> S2> S10> S0, and the SGR of the shrimp under Treatment S0 is lower than that under Treatments S4 and S7 by 22.36% and 28.11%, respectively (P< 0.05). The minimal feed intake (FI) of the experimental animals occurs in Treatment S0 (84.04% and 88.54% of that under Treatments S4 and S7, respectively) (P< 0.05). There are no significant differences in the food conversion efficiency (FCE) of the shrimp under the five treatments (P> 0.05).

Cloning,characterization,and expression analysis of the DEAD-box family genes,Fc-vasa and Fc-PL10a,in Chinese shrimp (Fenneropenaeus chinensis)

RNA helicases of the DEAD-box and related families are involved in various cellular processes including DNA replication, DNA repair, and RNA processing. However, the function of DEAD-box proteins in aquaculture species is poorly understood at molecular level. We obtained the full-length cDNA sequences of two genes encoding helicase-related proteins, Fc-vasa and Fc-PL10a, from the testes of Chinese shrimp, Fenneropenaeus chinensis. The two predicted amino acid sequences contain all the conserved motifs characterized by the DEAD-box family and several RGG repeats in the N-terminal regions. Homology and phylogenetic analyses indicate that they belong to the vasa and PLIO subfamilies. The three-dimensional structures of the two proteins were predicted with a homology modeling approach. Both core proteins consist of two tandem RecA-like domains similar to those of the DEAD-box RNA helicase. Using reverse transcription-polymerase chain reaction （RT-PCR） and real-time PCR we found that Fc-vasa was expressed specifically in the adult gonads. Transcription decreased in the ovary but increased in the testis during gonadal development. Fc-PL10a expression was widely distributed in the tissues we examined. Using in situ hybridization, we demonstrated that the Fc-vasa transcript is localized to the cytoplasm of the spermatogonia and oocytes. Thus, our results suggest that Fc-wasa plays an important role in germ-line development, and has utility as a germ cell lineage marker which will help to generate new insight into the origin and differentiation of germ cells as well as the regulation of reproduction in F. chinensis.

Ultrastructure and Protein Composition Changes during Acrosome Reaction in the Sperm of Chinese Shrimp, Fenneropenaeus Chinensis

Egg water was used to induce acrosome reaction in mature sperm of Fenneropenaeus chinensis .Transmission electron microscope and SDS PAGE were used to study the ultrastructure and protein changes of the sperm in F.chinensis ,which has undergone acrosome reaction.The results demonstrated that the sperms from female thelycum could be induced acrosome reaction in vitro by egg water,which was a kind of egg jelly released from oocyte into seawater during oocyte activation.More than fifty percent of sperm finished acrosome reaction during the first 30 min, in vitro .The whole event consists of the retraction of the spike and acrosome exocytosis.Spike was retracted and fused to acrosome cap followed by the release of acrosome granules.When the original egg water was diluted 5 and 10 times,The diluted egg water also have the ability to induce sperm acrosome reaction,but the acrosome reaction rate is much lower than that of the original egg water in the same time.Capillary zone electrophoresis was used to detect the biochemical components of egg water.Egg water was composed of two different components,which were also demonstrated by SDS PAGE.The molecular weights of the two kinds of egg jellies are both about 200kDa.Gelatin substrate SDS PAGE results did not show any hydrolytic enzyme activity in egg water.After acrosome reaction,many sorts of proteins in sperm are degraded.When the reacted sperms were examined with gelatin substrate SDS PAGE,there were six major peptide bands with hydrolytic enzyme activity were detected.Their molecular weights are 200kDa,130 kDa,66 kDa,53 kDa,48 kDa and 41 kDa respectively.These hydrolases cannot be detected in the sperms before acrosome reaction.The acrosome reaction of Chinese shrimp, F.chinensis is much different to that of the sperm in the shrimp, Sicyonia ingentis ,which the acrosome reaction was clearly studied.There is not filament formation during the acrosome reaction in Chinese shrimp.The time of exocytosis in the sperm of Chinese shrimp is also much longer than that of the sperm of Sicyonia ingentis .

Heat-shock protein 70 expression in shrimp Fenneropenaeus chinensis during thermal and immune-challenged stress

Using western immunoblotting, we obtained heat-shock protein 70 (HSP70) induction data and distribution in different tissues from shrimp Fenneropenaeus chinensis during thermal and immune-challenged stresses. This is probably the first report of the effects of various stressors on the expression of HSP70 in shrimp. HSP70 was prominently induced in hepatopancreas and gills, but not in muscle, eyestalk and hemolymph, when the shrimp were exposed to heat shock and Vibrio anguillavium-challenged stresses. Cold shock and WSSV treatment had no significant effects on the levels of HSP70 expression in all tissues examined. HSP70 induction was greatest after 2 h exposure to heat shock stress, which was elevated after acute heat shock exposure of 10℃ above ambient temperature.

Genetic parameters for cold tolerance and body weight of Chinese fleshy prawn,Fenneropenaeus chinensis

The inability of Fenneropenaeus chinensis to tolerate low temperatures is of major economic concern in temperate climates,as it reduces their growing season and leads to over-winter mortality.In this study,the heritability of body weight under low grow-out temperature and cold tolerance in F.chinensis were first investigated and estimated using 88 ful-sib families,which might provide crucial information in Chinese fleshy prawn breeding programs.The heritability for body weight under suitable and low temperature of F.chinensis were both moderate（0.158 0±0.307 5 and 0.132 0±0.026 9 respectively）;the large coefficient of variation（approximately 21%） and moderate estimate of heritability for body weight indicated substantial potential for selective breeding.The heritability estimate for cold tolerance was low（0.019 2±0.023 5）,and showed no significant differences from zero（P〉0.05）.A weak genetic correlation between cold tolerance and body weight was also estimated in the present study,also showing no significant differences from zero（P〉0.05）.Thus,more research needs to be conducted on the more accurate heritability estimate of cold tolerance and genetic correlations between traits in F.chinensis to further improve the achievement of breeding goals.

Pedigree tracing of Fenneropenaeus chinensis by microsatellite DNA markers genotyping

Two microsateUite DNA loci were used to trace the pedigree structure of six families in the shrimp Fenneropenaeus chinensis. Four of the families were natural mating, and the others were mated by artificial insemination. Eleven alleles were acquired at two microsatellite DNA loci （locus RS0622 and locus EN0033 ） by investigating 145 offsprings and 11 parents. Five alleles were acquired from locus RS0622 and six from locus EN0033. As analyzed, the gene frequencies were between 0. 024 1 and 0. 493 1, the heterozygosity was 0.652 2 and 0.688 8, and the polymorphism information content （PIC） was 0.585 7 and 0.652 9 for the locus RS0622 and the locus EN0033, respectively. Twenty-three genotypes were detected and the genotypes of the losing parents were also inferred. The pedigrees of three F1 and three F2 generations were determined by matching the genotype at each locus.

Establishment of microsatellite-based triplex PCR for parentage analysis of Chinese shrimp Fenneropenaeus chinensis

Through exploring the microsatellite primers from the random genome sequences of Chinese shrimp （Fenneropenaeus chinensis）, some microsatellite primers were obtained with rich polymorphic genetic information, and a triplex PCR was established using three primers （RS1101, RS0683 and H081 primers）. By adjusting the final concentration of Mg^2＋, dNTP and primers, and using a touch-town PCR program, the optimum amplification parameters of PCR system were obtained, which could successfully amplify the three primers in a PCR reaction. In the denatured PAGE gel, the amplified DNA fragments of three primers RS1 101,RS0683 and H081 could be easily identified each other. For the triplex PCR system, the PPE （probabilities of paternity exclusion） is 0.967 9,and the DP （discrimination power） is 0.999 327.Using the triplex PCR to test ten individuals of a parentage and their parents, an individual was excluded from the parentage in all of the three microsatellite loci, which might be mixed into the parentage for some unknown reason such as factitious misplay. The triplex PCR will be of great practical value in identifying the parentages of F. chinensis.

Isolation, cloning and sequencing of AFLP markers related to disease-resistance traits in Fenneropenaeus chinensis

Amplified fragment length polymorphisms (AFLP) technique was used to analyze the fingerprint- ing of four successive generations of Fenneropenaeus chinensis to reveal their disease-resistance traits. Some loci showed quite different genetic frequencies due to artificial selection, which implied that these fragments were putative markers related to the disease-resistance trait. We developed a simple and effective method to fur- ther characterize these AFLP fragments. Specific AFLP bands were cut directly from polyacrylamide gels, re-amplified, cloned and sequenced. Eight putative genetic markers were sequenced and their sizes ranged from 63 to 209 bp. The sequences were submitted to dbGSS (database of Genome Sequence Survey); and the BLAST analysis showed low similarity to the function genes, indicating these markers were tightly linked to a dis- ease-resistance trait but were not functional genes.

Nitrogen and Phosphorus Budget of a Polyculture System of Sea Cucumber(Apostichopus japonicus), Jellyfish(Rhopilema esculenta) and Shrimp(Fenneropenaeus chinensis)

The nitrogen(N) and phosphorus(P) budget and the ecological efficiency of a polyculture system of sea cucumber(Apostichopus japonicus), jellyfish(Rhopilema esculenta) and shrimp(Fenneropenaeus chinensis) were studied in a cofferdam, 120.2 ha in size. The nutrients were supplied by spring tide inflow. In total, 139600 kg N yr-1 and 9730 kg P yr-1 input to the system; while 118900 kg N yr-1 and 2840 kg P yr-1 outflowed from the system concurrently, thus the outflow was 85.7%(N) and 29.2%(P) of inflow. The production of N and P was 889.5 kg yr-1 and 49.28 kg yr-1(sea cucumber) and 204 kg yr-1 and 18.03 kg yr-1(jellyfish and shrimp), respectively. The utilization rate of N and P by polycultured animals was 7.8‰ and 6.9‰, respectively, 21.9% and 38% higher than that of monocultured sea cucumber. Our results indicated that the polyculture system was an efficient culture system of animals and a remediation system of coastal environment as well; it scavenged 14.3% and 70.8% of N and P, respectively. Such an ecological efficiency may be improved further by increasing either the stocking density or the size of sea cucumber or both.

Expression profiles of penaeidin from Fenneropenaeus chinensis in response to WSSV and vibrio infection by real-time PCR

Penaeidin from Chinese shrimp (Fenneropenaeus chinensis) has proved to be one of the most important antimicrobial peptides in the bodies of animals. The relative quantitative real-time PCR method is developed to study through time, the mRNA expression profile of penaeidin in the muscle and haemocyte tissue of Chinese shrimp infected with vibrio (Vibrio anguillarum) and WSSV (white spot syndrome virus). Research results showed that the same pathogens infection experiments produced similar gene expression profile in different tissues while different expression profiles appeared in the same tissues infected by different exterior pathogens. In vibrio infection experiments, a 'U' like expression profile resulted. Expression levels of penaeidin increased and surpassed the non-stimulated level, indicating that penaeidin from Chinese shrimp has noticeable antimicrobial activities. In WSSV infection experiments, the expression profile appeared as an inverse 'U' with the expression of penaeidin gradually decreasing to below baseline level after 24 h. The expression of antimicrobial peptides gene in mRNA level in response to virus infection in shrimp showed that international mechanisms of virus to haemocytes and microbial to haemocytes are completely different. Decline of penaeidins expression levels may be due to haemocytes being destroyed by WSSV or that the virus can inhibit the expression of penaeidins by yet undiscovered modes. The expression profiles of penaeidin in response to exterior pathogen and the difference of expression profiles between vibrio and WSSV infection provided some clues to further understanding the complex innate immune mechanism in shrimp.

The Complete Sequence of Mitochondrial COII Gene of Fenneropenaeus chinensis and Its Applicability as a Marker for Phylogenetic Analysis

The complete mitochondrial cytochrome oxidase subunit Ⅱ （COⅡ） gene of Penaeinae shrimp Fenneropenaeus chinensis was cloned and sequenced. The gene is 688 bp in length and codes for 229 amino acids. It shows 83.2%, 87.0% and 83.8% sequence similarity to Marsupenaeus Japonicus, Penaeus monodon and Farfantepenaeus notialis, respectively. The A＋T content of the whole gene and that at the third position of codons are 64.7% and 78.2%, respectively. The phylogenetic relationship between F. chinensis and three other species representing genera Farfanatepenaeus, Marsupenaeus and Penaeus was analyzed. Results showed that the genetic distances among the four taxa ranged from 0.144 0 to 0.200 5, exceeding those estimated with COⅠ and partial 16S rRNA gene sequences among Marsupenaeus, Litopenaeus and Melicertus, and being therefore larger than the value among subgenera. It has been suggested that the COⅡ gene has a faster evolutionary rate than that of the COⅠ gene and partial 16S rRNA gene and could be used for phylogenetic analysis at genus or species level. The results of the present study indicated that Farfantepenaeus, Fenneropenaeus, Marsupenaeus and Penaeus are at a higher phylogenetic level than subgenus, which supports the opinion of the elevation of phylogenetic status of the four subgenera to genus level.

Partial Sequence Analysis of Mitochondrial COI Gene of the Chinese Shrimp,Fenneropenaeus Chinensis

Eight hundred and thirty eight base pair fragment of mitochondrial COI gene of wild and cultured populations (CP1, CP4, CP5 and CP6) of Fenneropenaeus chinensis was amplified and sequenced. The A, T, G and C contents of the sequence were 235bp(28.0%), 307bp(36.6%), 138bp(16.5%) and 158bp(18.9%), respectively. Furthermore, 556bp fragment of the sequence was used to discuss the phylogenetic relationship among 14 Penaeidae species using Alpheus armillatus as the outgroup. From the molecular phylogenetic tree constructed by neighbor-joining method, we obtained three large shrimp groups:Farfantepenaeus, Litopenaeus and Fenneropenaeus group. The results also indicated that there were a closer genetic relationships between F. aztecus and F. paulensis, L. schmitti and L. setiferus, F. indicus and F. merguiensis, and the genus Farfantepenaeus was closer to Litopenaeus.

Using SSR Marker to Trace Chinese Shrimp Fenneropenaeus chinensis Released in Natural Sea-A Feasible Strategy for Assessment of Release Effect in Natural Resources Recovery Program

Enhancement release has been proven effective in natural resources recovery of Chinese shrimp Fenneropenaeus chinensis in the last several decades in China, however, to assess the effectiveness of enhancement release, we still need to develop a high-efficient and easy-operational method to replace those physical-tagging release method with labor intensive, size-and number-limited. In the present study, single(with maternal known) parentage identification using eight simple sequence repeat(SSR) markers genotype fingerprint was used to trace Chinese shrimp released in Bohai Bay in 2013. A total of 884 shrimp spawners were collected from two hatcheries in Tianjin City respectively after enhancement release of shrimp larvae in May 2013. A total of 844 shrimp samples were recaptured around the release location approximately 4 months after the shrimp larvae were released into the natural sea. Genotype data of 8 SSR loci of the 1,726 samples were used for maternal-offspring parentage identification using CEervus 3.0 software. The allele number in each locus ranged from 8 to 68 with an average value of 33.25, which produced the cumulative exclusion probability with one parent known of all these sight loci up to 99%. Among the 844 recaptured shrimp samples, 448(♂:♀=212:232, gender information was lost for 4 samples) were successfully traced to their 337 maternal parents using a logarithm of odds(LOD) > 3.0 threshold. Among these 337 maternal parents, 253 had a single offspring, 62 had two offspring, 18 had three offspring, 3 had four offspring, and 1 had five offspring. For the first time, a large number of released shrimp were identified from recapture samples, and this study showed that it is possible to trace all released Chinese shrimp without using any type of physical tag in enhancement release activities. This not only means more precise recapture ratio assessment than ever expected, but also this method demonstrates an effective method for large-scale hatchery release as well as for organisms used in hatchery enhancement which are not suitable for physical tagging.

Effects of Salinity Fluctuation Frequency on the Growth, Molting Rate and Hemolymph 20-Hydroxyecdysone Concentration in Juvenile Chinese shrimp, Fenneropenaeus chinensis

This experiment was conducted to examine the effects of salinity fluctuation frequency on the growth, molting rate and hemolymph 20-hydroxyecdysone （20-HE） concentration for juvenile Fenneropenaeus chinensis with an initial wet body weight of 1.115 g±0.012 g. The salinity of the control treatment （represented by DO） was 28 throughout the experiment, whereas treatments D2, D4, D6 and D8 were subjected to different salinity fluctuation frequencies of 2, 4, 6 and 8 d, respectively. The range of salinity fluctuation was 4. The salinity in treatments D2, D4, D6 and D8 was kept at 28 for 2, 4, 6 and 8d, respectively; each original salinity was decreased abruptly to salinity 24, which first lasted for another 2 d and was then raised to its initial value 28. This constituted a salinity fluctuation cycle and afterwards the cycle repeated. It was found that： 1） The weight gain of shrimp in treatment D4 was 202.9% and significantly higher than that in treatment DO （P〈0.05）. The molting rate in treatment D2 was the lowest, while that in treatment D6 was the highest and significantly higher than those in treatments DO and D2 （P〈0.05）. 2） The hemolymph 20-HE concentration of shrimps in all treatments was at low levels and increased first gradually during the inter-molt period and then increased sharply. It reached a peak value during the pre-molt stage, and then decreased abruptly during the post-molt stage when the lowest level occurred. 3） During the post-molt stage, the hemolymph 20-HE concentration in treatment D2 was 7.47pg μL^-1 and significantly higher than that in treatment DO （P〈0.05）. There were, however, no significant differences in hemolymph 20-HE concentration among all five treatments during the inter-molt stage （P〉0.05）. During the pre-molt stage, the hemolymph 20-HE concentration in treatment D6 was significantly higher than that in treatment DO （P〈0.05）, whereas the hemolymph 20-HE concentration in treatment D2 was significantly lower than that in other treatments （P〈0.05）. Adequate salinity fluctuation promoted the molting rate through increasing hemolymph 20-HE concentration at the pre-molt stage.

Genetic diversity analysis of spawner and recaptured populations of Chinese shrimp(Fenneropenaeus chinensis)during stock enhancement in the Bohai Bay based on an SSR marker

Eight microsatellite markers were used to analyze genetic diversity, level of inbreeding, and effective population size of spawner and recaptured populations of Chinese shrimp（Fenneropenaeus chinensis） during stock enhancement in the Bohai Bay in 2013. A total of 254 and 238 alleles were identified in the spawner and recaptured populations, respectively, and the numbers of alleles（N_a） were 8–63 and 6–60, respectively. The numbers of effective alleles（N_e） were 2.52–21.60 and 2.67–20.72, respectively. The polymorphism information content ranged from 0.529 to 0.952. The observed heterozygosity（H_o） values（0.638–0.910 and 0.712–0.927） were lower than the expected heterozygosity（H_e） values（0.603–0.954 and 0.625–0.952）, which indicated that the two populations possessed a rich genetic diversity. In 16 tests（2 populations×8 loci）, 13 tests deviated from the HardyWeinberg equilibrium. F_（is） values were positive at seven loci and the inbreeding coefficients（F） of the two populations estimated by trio ML were 13.234% and 11.603%, suggesting that there was a relatively high degree of inbreeding. A certain level of inbreeding depression had occurred in the Chinese shrimp population. F_（st） values ranged from 0 to 0.059, with a mean of 0.028, displaying a low level of genetic differentiation in the two populations. Effective population sizes（3 060.2 and 3 842.8） were higher than the minimum number suggested for retaining the evolutionary potential to adapt to new environmental conditions. For enhancement activity in 2014,the ideal number of captured shrimp spawners should have ranged from 7 686 to 19 214 to maintain genetic diversity and effective population size. Further strategies to adjust the balance of economic cost, fishing effort and ideal number of shrimp spawners to maintain a satisfactory effective population size for ensuring the sustainability of Chinese shrimp are proposed.

Research in migration route of hatchery released Chinese shrimp(Fenneropenaeus chinensis) in the Bohai Bay using method of SSR marker

This study provides new insights for the hatchery released Chinese shrimp(Fenneropenaeus chinensis),including proportion,dynamic migration route,after they were released into nature for stock enhancement using a new strategy quite different than ever.Chinese shrimp were sampled at 22 survey stations during two investigation voyages acrossing 74 survey stations in the Bohai Sea from July 16 to August 9 in 2015.Among 289 sampled individuals during the second voyage,totally 155 shrimps were identified as hatchery shrimp released into the Laizhou Bay at mid-May in 2015 based on finger-print of eight SSR(simple sequence repeats)markers,and the proportion of hatchery released shrimp in recapture samples were from 41.30%–85.71%in each station with an average value 53.63%,which verified a previous view point that up to 90%of autumn season Chinese shrimp landing in the Bohai Sea were composed of hatchery released.Meanwhile,the dynamic migration route of hatchery released shrimp revealed that part of released shrimp migrated heading northwest along the west coast of the Bohai Sea up to the Bohai Bay but just remained at the Laizhou Bay until over-wintering migration at midOctober when they initiate over-wintering migration.Present unnatural spring season shrimp fishing model cut the throat of spawner shrimp chance to swim back to their respective spawning plants at each spring,it still no chance to clarify whether the hatchery released shrimp could replenish to the reproduce population and complete a whole life cycle as same as their natural relatives.