Abstract:Embryos and larvae of the prosobranch gastropod mollusk Rapana venosa were artificially incubated and hatched from egg masses under laboratory conditions,and morphological changes during the early development were observed.Fertilized eggs developed into veligers in about 16 days at temperature 25 ℃.Embryonic development included six stages:cleavage,blastula,gastrulae,trochophore in egg membrane,intra-membrane veliger,and veliger.The planktonic larval development was divided into five stages,including one-spiral whorl stage,two-spiral whorls stage(early,mid and late),early three-spiral whorls stage,mid and late three-spiral whorls stage,four-spiral whorls stage(early,mid and late).The highest growth rate of larvae was observed during the late two-spiral whorls stage with an increase of 44.45 μm in shell height per day,while the lowest was in early three-spiral whorls stage with an increase of 19.51 μm in shell height per day.The settlement and metamorphosis of veligers occurred in the mid-to-late four-spiral whorls stage with the shell height of 1 250-1 500 μm.Morphological changes during the settlement and metamorphosis of veligers could be summed up as:incrassation of edge of shell aperture,exstrophy of shell aperture,disappearance in the middle edge of shell aperture,degeneration of velum of veligers,and the broadened feet which could flex freely.

Abstract:A field experiment of different density of three shellfish ages was carried out in the sea of raft culture of Pationopecten yessoensis in Changhai County from August 2009 to July 2010 to study the self-thinning effect and to estimate the optimal culture density using the monthly data of the growth of shell length,wet weight growth and cumulative mortality.No statistical difference was found in the anniversary shell length growth(P>0.05)in different density for the surveyed scallop samples of every shellfish age.The shell length of the first-year scallop grew fastest with an average annual growth 29.53 mm,followed by 23.50 mm for the second-year shell growth and 15.47 mm for the third-year shell.The anniversary of wet weight growth was not significantly different(P>0.05)either,the wet weight growth of the first-year scallop,the second-year and the third-year scallop were 14.69,37.80 and 54.07 g,respectively.The difference in cumulative mortality of different density groups for second-year and third-year shellfish was not statistically significant(P>0.05) with the third-year shellfish mortality ranging from 76.30% to 83.33% and the second-year shellfish mortality rate ranging from 88.89% to 91.78%.The cumulative mortality of the first-year scallop with cultural density of 150 ind/layer was significantly different(P <0.05)from that of the density of 80 ind/layer and 50 ind/layer.Based on self-thinning model,the suitable raft breeding density is 4-5 ind/layer in third-year scallop,8-16 ind/layer in second-year,29-124 ind/layer in first-year,respectively.

Abstract:The present experiment simulated the temperature fluctuation during the culture period of grass carp(Ctenopharyngodon idellus)to examine the effects of the changes in temperature on the budgets of C,N and P nutrients.Grass carp were cultured at temperatures of 15,18,24 and 30 ℃ and the processes of C,N and P budgets were examined.The results showed that C,N,P nutrient budgets of grass carp were significantly different between the 4 temperature groups(P<0.05).The feed uptake rate,nitrogen excretion rate,phosphorus excretion rate and fecal production rate of grass carp were 3.405 7,7.533 4,0.000 8 and 0.601 3 mg/h at 15 ℃,respectively,which were significantly lower than other groups(P<0.05),and reached the maximum values at 24 ℃,which were 10.442 0,18.995 6,0.001 7 and 1.647 0 mg/h,respectively.The oxygen consumption rate(OR)increased with increasing temperatures(T)following the formula OR=0.005 9×T^1.2532(R²=0.84).The scope for growth(SFG)of C,N and P of grass carp were 1.064 9,0.126 4 and 0.018 8 mg/h at 15 ℃,respectively,which were significantly lower than other groups(P<0.05),and reached the maximum values at 24 ℃,which were 3.402 8,0.397 1 and 0.071 8 mg/h,respectively.The absorption efficiencies of C,N and P of grass carp were 81.38%,83.05% and 80.30% at 15 ℃,respectively,which were significantly lower than the 24 ℃ and 30 ℃ groups(P<0.05).

Abstract:In order to investigate the relationships among growth,nitrogen budget,water temperature and fish size of cobia,by using the principles and methods of fish bioenergetics,a laboratory experiment was carried out to study the effects of water temperature(21,27 and 33 ℃)and fish size(about 10,20,50 and 100 g)on growth and nitrogen budget,and furthermore,the growth models in relation to water temperature and fish size and the nitrogen budgets at different temperature and size treatments were established in this paper.The results showed that:(1)Growth of cobia was affected significantly by water temperature and fish size as well as their interaction.The fastest growth rate occurred for cobia with initial body weight about 10 g at 33 ℃ and the lowest growth rate occurred for cobia with initial body weight about 100 g at 21 ℃ within the experimental temperature and size ranges.(2)In a given size group for cobia,SGR increased with temperature.At a given temperature,SGR decreased with fish size,and the relationships between SGR and W could be described as power functions for cobia.By using multiple regression analysis,the model,LnSGR=a bLnW cT dT² eTLnW,provided a good fit to the data of specific growth rate(SGR),water temperature(T)and fish size(W).(3)Within the experimental water temperature and body size weight ranges,food nitrogen,feces nitrogen,excretion nitrogen and growth nitrogen of cobia were influenced significantly by water temperature and fish size,and increased with temperature but decreased with fish size.(4)Nitrogen budgets differed as water temperature and fish size changed,and were more sensitive to water temperature than to fish size.In a given size group the proportion of food nitrogen allocated to growth at 27 and 33 ℃ was much higher than that at 21 ℃,but contrary to the proportion of food nitrogen lost in excretion.At a given temperature the variation of nitrogen budgets among different size groups was small.(5)More than 68% of food nitrogen was lost in excretion.So it could be concluded that relatively low water temperature made an obviously depressed impact on cobia growth,and nitrogen excretion was the main way of nitrogen expenditure from food for cobia,and nitrogen budgets of cobia were relatively constant at 27-33 ℃ within the experimental temperature and size ranges.

Abstract:The specific growth rates(SGR),growth hormone(GH),survival rate,feed intake ratio,feed conversion efficiency(FCE)and body composition in muscles of juvenile turbot(Scophthalmus maximus)［body weight of(7.16±0.07)g］,which had been reared at salinities 12,18,24,30 and 36 for 60 days,were investigated.The results showed that the SGR of the fish reared at salinity 18,24,30 and 36 were 1.97,1.87,1.87 and 2.00 %/d,respectively,with a survival rate of 100%for these groups(P>0.05).However,the SGR and survival rate of the fish reared at salinity 12 were 1.45 %/d and 80.77%,respectively,both of which had significant differences in comparison with those of the control(salinity 30)(P<0.05).GH was the lowest in the fish reared at salinity 12 and the highest at salinity 36,both of which had significant differences in comparison with that of the control(P<0.05).FCE and feed intake ratio were 1.12%-1.38% and 1.19-1.28 %/d,respectively.FCE was the lowest in the fish reared at salinity 12,and the highest at salinity 36,both of which had significant differences in comparison with that of the control(salinity 30)(P<0.05);while feed intake ratio was the highest at salinity 30,and the lowest at salinity 12,with significant differences compared with that of the control(P>0.05).Although SGR had not significantly correlative with salinity,SGR increased with the rise of FCE and GH.The crude protein decreased with the rise of water salinity and showed significant difference between groups(P<0.05).Fish reared at salinity 12 had the lowest crude fat and highest ash content ,both of which were significantly different from the control(P<0.05).Moisture had no significant differences between groups(P>0.05).Thus,the results indicated that the changes in salinity could have significant impacts on SGR,GH,FCE,feed intake ratio and protein in muscles of juvenile turbot.Rearing in brackish water can enhance growth performance and flesh quality of the fish,and the proper salinity is 18.The results from this study provide important reference for salinity selection in turbot mariculture.

Abstract:To study the germplasm resources and genetic diversity in the wild population of Orithyia sinica,the mitochondrial DNA 16S rRNA and COⅠ gene sequences were obtained from O.sinica wild populations by PCR amplification.A T base content of 16S rRNA and COⅠgene sequences were 67.7% and 61.4%,respectively,which were significantly higher than G C base content.From 515 bp of 16S rRNA gene sequences,4 haplotypes and 4 polymorphic sites were detected,and they were all singleton variable sites.As for 653 bp of COⅠ gene sequences,11 haplotypes and 23 polymorphic sites were detected,including 18 singleton variable sites and 5 parsimony informative sites.COⅠ gene sequences have more variations than 16S rRNA gene sequences,indicating that COⅠ gene sequences were suitable for analysis of genetic diversity of O.sinica.The results of genetic distances and phylogenetic analysis of 16S rRNA and COⅠ gene sequences were consistent with each other,showing that O.sinica have much closer relationship with crabs of Portunidae,and crabs of Grapsidae were together with that of Ocypodidae,which were consistent with classical taxonomy.Differentiation time of 11 species of crabs and vertebrates was deduced based on the genetic distance of 16S rRNA gene sequences,and the results showed that the radiation differentiation time of four families of crabs was between Paleocene and Eocene.This study is expected to provide important information for the protection and utilization of O.sinica resources of China.

Abstract:Dense phase carbon dioxide(DPCD)is a promising non-thermal processing technology that affects microorganisms and enzymes through molecular effects of CO₂ under pressures below 50 MPa and temperature below 60 ℃.DPCD could affect food physical,nutritional,sensory qualities.In these experiments,compared with fresh shrimp(Litopenaeus vannamei),the effects of dense phase carbon dioxide(DPCD)and heat treatment on the nutrient components,mass loss,pH value,water-holding capacity,texture,protein and flavor components of shrimp meat were investigated.The results were as follows:compared with fresh shrimp,the water and crude fat content of shrimp meat treated by DPCD decreased significantly(P<0.05)and the crude protein content of that had no significant change(P>0.05),while the crude protein and fat content of shrimp meat treated by heat decreased significantly(P<0.05);the mass loss of shrimp meat treated by DPCD was 16.02%±1.90%,but DPCD had no significant effect on pH value of shrimp meat(P>0.05);DPCD and heat treatment could induce shrimp protein denaturation,which caused water holding capacity of shrimp meat decreased significantly(P<0.05),from(84.79±5.25) g/100 g to (65.18±2.06) g/100 g and (65.58±2.08) g/100 g respectively;DPCD treatment has no significant effect on hardness of shrimp meat(P>0.05),while heat treatment caused hardness of shrimp meat to increased significantly(P<0.05),from (3.48±0.49) N to (7.37±0.76) N;DPCD and heat treatment caused springiness of shrimp meat to decrease significantly(P<0.05),from 0.88±0.08 to 0.71±0.03 and 0.78±0.03 respectively;except for betaine,PO^3-₄ and Cl^-,the contents of other taste-active components(free amino acids,ATP related compounds,organic acid,and glycogen etc.)had no significant difference(P>0.05)between DPCD treated and fresh shrimp,but heat treatment led to significant loss of shrimp meat taste-active components(P<0.05).These results indicated that negative effects of DPCD treatment on shrimp meat qualities were less than those of heat treatment.

Abstract:Ten cultivated strains of Pyropia yezoensis were studied in this research in order to identify the effects of the strain difference and the harvesting time difference on the fatty acid composition and content of P.yezoensis. The results showed that the fatty acid composition of these ten P.yezonsis samples was not affected;however,the content of each fatty acid was affected and the difference among ten samples was significant.The saturated fatty acids (SFAs)were mainly composed of 13∶0,16∶0,18∶0 with 16∶0 as the highest component(about 20%).The unsaturated fatty acids(UFAs)included 18∶1 n-9,18∶2 n-6,18∶3 n-3,20∶1 n-9,20∶2 n-7,20∶3 n-7,20∶4 n-6(AA),20∶5 n-3(EPA)and the major componet was EPA(about 50%).Samples harvested during the lowest water temperature period(February)contained the highest total fatty acids and EPA concentration;the result indicates that the low water temperature has advantages in accumulating fatty acids especially UFAs of P.yezoenis.P.yezoensis is rich in UFAs(especially EPA).The n-6/n-3 ratios ranged from 4.9 to 7.7 during the whole study period,and this range is consistent with the recommended diet ratio of WHO/FAO.

Abstract:Carbon tetrachloride(CCl₄)has been widely used as a kind of classic liver poison in constructing mammalian liver injury model and screening liver protecting drug.To investigate toxicity effects of CCl₄ on hepatocyte DNA of Cyprinus carpio var.Jian,the alkaline single-cell gel electrophoresis(comet assay),histopathological examination of liver and the measuring of biomarkers of hepatocyte damage were performed respectively after low,middle and high concentrations(6.25% and 12.50% and 15.00% CCl₄ in olive oil,v/v)of CCl₄ at a volume of 0.01 mL/g of body weight being injected intraperitoneally into C.carpio var.Jian for 72 h.Meanwhile,the Real-time PCR was carried out to elevate the effects of CCl₄ on CYP3A mRNA expression.Results showed that the group injected with 6.25% of CCl₄ for 72 h has no obvious change(P>0.05)on histopathological examination,serum hepatase activities and mRNA expression of CYP3A,compared to the control,however,the comet assay results of hepatic cells showed that tail length,tail DNA(%),tail moment and olive tail moment increased significantly(P＜0.01).With the increase of concentrations,histological changes such as cell swelling,extensive vacuoles degeneration,karyopyknosis and karyolysis were observed.The groups injected with 12.5% and 15% of CCl₄ could significantly elevate the serum levels of glutamate oxalate transaminase(GOT)and glutamate pyruvate transaminase(GPT)(P<0.01 or P<0.05),and the group with 15.00% of CCl₄ produced a significant effect in the case of lactate dehydrogenas(LDH)and malondialdehyde(MDA)(P<0.05).All damage indexes of comet assay also increased with the increase of CCl₄ concentrations(P<0.01).At the same time,the expressions of CYP3A of the groups injected with 12.5% and 15% of CCl₄ were significantly reduced(P<0.05).Overall results proved the toxicity effects of CCl₄ on hepatocyte DNA of C.carpio var.Jian.Within the range of experimental concentrations,CCl₄ could inhibit CYP3A mRNA expression.And the results of serum hepatase activities,histopathological examination and comet assay were observed not only in a dose-dependent manner but also having good coherence with the increase of CCl₄ concentrations.The technique of comet assay showed higherr sensitivity.

Abstract:In order to assess the changes of the intestinal microbial community after the feeding conversion of grass carp(Ctenopharyngodon idellus),we analyzed the intestinal microbial communities of grass carp by PCR-DGGE.The results indicated that there were significant differences among the intestinal microbial communities from the grass carps caught in different months.However,the sample size and fullness were not detected to have significant correlation with the intestinal microbial community,which were generally recognized as the factors influencing the intestinal microbial community.These results implied that environmental difference probably is the most important factor influencing the intestinal microbial community in a short-term.Our results will provide the basic information to elucidate the change rule of intestinal microbial community of grass carp,and the action mechanism of the intestinal probiotics,the relationship between intestinal microbes and the fish diseases.

Abstract:In this study,using the methylation sensitive amplified polymorphism(MSAP)method,we globally assessed the effect of low temperature adaptation on the level and variations of cytosine methylation alterations at CCGG sites of genomic DNA in Nile tilapia(Oreochromis niloticus)strains with good cold-resistance characters developed by the successive and directional selection breeding of multi-generations.Total of 849 fragments were identified by 18 pairs of se1ective primer combinations of which 411 and 438 were detected in cold-resistance tilapia strain and the control,respectively.Among these fragments,the methylation sites were 72 and 104,and the corresponding total-methylation levels were at 17.52% and 23.74%,respectively.The full methylation sites at the internal Cs were 37 and 65,and the corresponding full methylation levels were at 9.00% and 14.84%,respectively,and the hemi methylation sites at the external Cs were 35 and 39,and the corresponding hemi-methylation levels were at 8.52% and 8.90% in cold-resistance tilapia strain and the control,respectively.Further analysis of DNA methylation indicated that a statistically decrease in the overall level of total-methylation levels and both methylation types was detected in cold-resistance tilapia strain compared with the control(decrease at 6.22%,5.84% and 0.38%,respectively),and the changes of DNA methylation pattern were recognized mainly in the full methylation sites.The level of decrease in DNA methylation suggested that the levels of genomic DNA methylation were changed during the successive cold stress of multi-generations in tilapia,and it also indicated that DNA methylation alteration in tilapia treated with cold stress was mainly through de-methylation that occurred in some CCGG sites.All these results implied that the change of DNA methylation was closely associated with cold tolerance of tilapia.The present findings are valuable to further explore the application potential of DNA methylation alteration in tilapia genetic improvement and provide a new method and theoretical basis for fish stress resistance breeding.

Abstract:Vibriospecies are the causative agents for vibriosis,the most serious aquaculture disease worldwide.Probiotics are well known to have the potential for broad use in aquaculture environments.In this study,the aim is to screen the probiotic candidate strain from the intestinal tract of healthy,aquaculture-raised large yellow croaker(Pseudosciaena crocea)for the aquaculture.We identified the strain by rapid identification system and 16S rDNA gene sequence analysis.Based on the both identification results,strain X93 was identified as Bacillus pumilus(GenBank accession No.HM137033).We also checked its antagonistic activities against pathogenic Vibrio parahaemolyticus (Vp-1.2164)and Vibrio alginolyticus (Va-Y)by the dot-inoculating method and tested the effects of temperature,salinity,pH,proteinase K and FeCl₃ on the antibacterial activity of the extracellular products.The results indicated that strain X93 could strongly inhibit indicator bacterial strains,such as Vibrio parahemolyticus,Vibrio alginolyticus,Edwardsiella tarda and Aeromonas hydrophila,exhibiting a very broad antibacterial spectrum.The cell-free antibacterial extracellular products secreted by strain X93 most strongly inhibited Vibrio parahemolyticus(Vp1.2164)and Vibrio alginolyticus(Va-Y)when X93 was cultured at 28 ℃ and 5 salinity for 48 h.Our data suggest that strain X93′s antibacterial extracellular products exhibit a fairly broad tolerance to pH,temperature,salinity,and FeCl₃.The antibacterial activity of the extracellular products,however,is proteinase K-sensitive,indicating that the active components are proteinaceous.In summary,the results presented here demonstrate that Bacillus pumilus strain X93 can be considered a probiotic since its secreted extracellular products are able to inhibit pathogenic Vibrio,which could have useful antibacterial applications.On a broader level,these results point to the potential for isolating bacteria with novel antibacterial activity from cultivated large yellow croaker.Most importantly,these results provide the necessary data for further development of probiotic products that inhibit pathogenic bacteria in aquatic environments.

Abstract:16 selected populations were injected with bacteria(Vibrio alginolyticus)suspension to know deeply about disease resistance of Macrobrachium rosenbergii.Bacterial challenge experiments demonstrated that there were big differences in disease resistance among the 16 selected populations.Some families exhibited strong disease resistance to bacterial infection,while some families were not resistant to bacterial challenge.Among the 16 selected populations,3 populations(population SCR11-6,SCR11-11 and SCR11-16)with strong disease resistance with a survival rate of 80% were identified,7 populations with secondly strong disease resistance,4 populations with normal disease resistance with a survival rate of 65%-70%,and 2 populations with low disease resistance with a survival rate of 49.53% and 35.0% were identified.The genetic structure of 16 selected populations was analyzed assessed by 8 microsatellite markers.The results showed that the number of total alleles was 53.The numbers of allele at each locus ranged from 5 to 9 with an average of 6.625,and polymorphic information content(PIC)was 0.629 4-0.829 4,and the average was 0.732 3.The mean polymorphism information content in 16 selected populations was 0.493 2-0.695 6.The average observed and expected heterozygosity of the 16 selected populations varied from 0.506 2 to 0.651 3 and from 0.551 9 to 0.733 2,respectively,and the average genetic similarity coefficient and genetic distance between them was 0.655 2 and 0.434 4,respectively.Besides,after PCR amplification on the individuals of DP and SP populations,differential bands were calculated and the correlation between growth trait and microsatellite loci was established.The results showed that 5 loci were correlated with disease resistant trait,of which MRMB11 had extreme significance of 0.282.These results indicated that 4 of 16 selected populations had strong disease resistance and high genetic diversity.The development of these 8 populations lays foundation for selective breeding of M.rosenbergii with disease resistance.

Abstract:In this study,two bacteria strains SX01 and SX02 were isolated from diseased Acipenser schrenckii and the carps(Carassais auratus gibelio)were artificially challenged to test the pathogenicity of the strains.Morphology profiles were observed,physical and biochemical characteristics were tested,and molecular analysis was combined to identify the isolated strains,also antibiotics drug resistance genes were detected.The results showed,the strains were pathogenic to the carps,with the 96 h LD₅₀=1.02×10⁹cells/mL.The strains were Gram negative,short rods,nearly sphere,oxidation test and motility negative,catalase positive,showed the profiles of Acinetobacter genus.16S rRNA gene sequence of the strains shared 100% identity with those published data of A.junii in GenBank,and rpoB sequence of SX01 showed 99% identity with those of A.junii,were well identified the strains to A.junii.A β-lactam enzyme coding gene TEM-1 and acetamide transferase gene Aac(3)Ⅱ were detected in the strains,suggesting possible clinical contamination.Enough attention must be paid to guard against the drug-resistant A.junii in aquaculture and food sanitation.

Abstract:Glucose regulated protein 78 ku(GRP78)was one member of heat shock protein 70(HSP70)family.As a molecular chaperone,GRP78 plays important roles in regulating the protein folding and maintaining the stability of endoplasmic reticulum.In this study,we firs cloned the full-length cDNA sequence of GRP78 from mud crab,Scylla paramamosain using RT-PCR and RACE.The full-lengty of GRP78 cDNA is 2 284 bp with 1 962 bp open reading frame encoding 653 amino acids.The homologous analysis indicated that the deduced amino acids contained the signature sequences of HSP70 and the endoplasmic reticulum retention sequence in the C-terminal domain.The deduced amino acid sequence shared high identity with previously reported GRP78s.RT-PCR indicated that GRP78 was expressed in various tissues.When S.paramamosain juveniles exposed to different temperatures and salinities after 12 hours,the expression of GRP78 gene increased with the rise of environmental temperature and a high expression of GRP78 was detected in high salinity(30).So we infer that GRP78 in S.paramamosain might participate in protein folding and the response to environmental stress.

Abstract:Acute viral necrosis virus(AVNV),which caused mass mortality of scallops Chlamys farreri,is a DNA virus.In the present study,the detection of AVNV was conducted on culture scallops from different culture modes and seeds to search appropriate culture modes and seeds which could reduce mortality of culture scallops.Ten adult scallops were sampled regularly from scallop single-cultured system(Liuqing River,Qingdao)and scallop-kelp co-cultured system(Sanggou Bay,Rongcheng)per month,both contained scallops originating from wild-seed and artificial-seed(March 2010- April 2011,total 480 scallops were sampled).The scallops were taken to the lab at low tempreture.Mantle tissue DNA was extracted and used as the template for nest-PCR to evaluate infection of AVNV.The results showed that the infection rates of AVNV for cultured scallops from wild-seed and artificial-seed were 21.1% and 18.9% in Liuqing River,while in Sanggou Bay the infection rates were 11.1% and 5.6%.In both sampling sites,high infection rates were detected in July and August.Highest infection rate in Liuqing River reached 80%,while in Sanggou Bay that was only 40%.The present study indicated that scallop-kelp co-cultured system and artificial-seed could effectively decrease the infection rate of AVNV,which could be useful methods to control occurrence of scallop disease.

Abstract:As an important source of air pollution,pollution emissions of fishing boats caused widespread concern in the international community.As a clean,renewable energy which has the similar performance to petroleum diesel that can be mixed for use in a diesel engine,biodiesel can be a better alternative energy in the post-oil era with significant emission reduction effects.This paper explored the reduction strategies of fishing boats using biodiesel based on evolutionary game theory.This paper analyzed the dynamic changes of the proportion of fishermen,fishermen and enterprises that adopted different strategies with bounded rationality,as well as the conditions for stable strategy.This paper considered that subsidy policy of the government,supervision of the fishing department and effective implementation of carbon trading can change the fishermen’ benefit matrix to induce fishermen to reduce emissions by using alternative energy sources.This paper estimated the cost abatement of Chinese fishing vessels.The results showed that fishing boat engine blended 5 percent biodiesel would result in an average annual increase in cost by nearly 3000 yuan per boat.If the government is able to develop biodiesel subsidy policy and establish an effective carbon trading system,with no increase in the cost,the fishermen will gradually tend to use biodiesel for fishing boats emission reduction.

Abstract:The Pacific oyster Crassostrea gigas,naturally occurring in Japan,China and Korea,is a major global aquaculture species.It is economically important and has had the highest worldwide production in any cultured aquatic animal species since 1993.China produced over 3.5 million tons of cultured oysters,and C.gigas is one of the most important species.In view of the importance of this species,conventional selections have been carried out worldwide in order to increase growth rate,and to improve survival.However,nearly all the broodstock of oyster used remains unselected in China.In order to improve the productivity traits of C.gigas,a selective breeding program for faster growth was initiated in 2006.From 2007,successive generation of mass selection for fast growth in shell height was conducted in three C.gigas stocks from China,Japan and Korea.The progeny of the third generation of the three C.gigas breeding lines(CS3,JS3,and KS3)were compared with the controls in a 420-day farming experiment.Mean shell height and mean total weight of the oysters from all three selection lines were significantly greater than those of controls(P<0.05),respectively.At harvest on day 420,the increase in shell height for the three selection lines over the controls were 13.4%,10.1% and 10.5%,the increase in weight were 18.5%,13.4% and 11.6%.In the third generation of three C.gigas breeding lines,the realized heritability of shell height were 0.447±0.226,0.471±0.297 and 0.367±0.167.In addition,the genetic gain of total weight for the CS3,JS3,and KS3 was 16.01%±3.82%,15.03% ±5.21% and 11.57%±5.15%,respectively,demonstrating that total weight had been improved markedly during selection for shell height.These results indicate that the selection for fast growth achieved encouraging progress in the third generation of C.gigas breeding lines.

Abstract:Animal behavior is a direct response of animal to external stimuli and is one of the most important properties of animal life.The behavior of animals often provides first clue of environmental degradation.Animal behavior is one of most fundamental disciplines of biology,which is applied to all aspects of aquaculture,including domestication and captive rearing,selective breeding,health monitor,preparing formulated feed,feeding,reproduction,larval metamorphosis,habitat selection,fighting and aggression,polyculture,and rearing system design.

Abstract:6 strains of Pyropia yezoensis (Ueda)M.S.Hwang et H.G.Choi were analyzed using SRAP(sequence-related amplified polymorphism)markers in order to identify the germplasm.DNAs from conchocelis of 6 strains were screened with 35 primer combinations,of which 11 primer combinations gave stable and reproducible amplification patterns.Among the total 131 fragments,125 fragments(95.42%)were polymorphic.The genetic distances of 6 strains were between 0.364 3 and 0.867 9,and the average was 0.593 0.Cluster analysis of UPMGA showed a good and true relationships among the 6 strains.The results demonstrated that SRAP could be a useful tool in germplasm identification of P.yezoensis strains.From the total 131 fragments,4 fragments amplified by 1 primer combination were used to develop the DNA fingerprints of 6 strains of P.yezoensis.One specific fragment of TM-18 was obtained in the fragments amplified by primer combination ME1/EM6.According to the DNA sequence of the fragments,a specific pair-primer was designed and it achieved stable amplification of a 340 bp specific band in both DNA of conchocelis and blades of TM-18.The specific marker could be used in fast identification of TM-18 strain.