Abstract:In order to establish artificial seeding techniques of Sargassum horneri, it was observed in this paper that release of eggs, embryology of zygotes, development and growth of juvenile sporophytes, and effect of culture conditions on germlings growth in laboratory culture. The results showed that the eggs released concurrently from the basal and middle section of female receptacles, and adhered to the surface of receptacles for fertilization and germination. Eight nuclei in a fresh released egg would intergrade after fertilization and then stated to nuclei fusion to form a larger central nucleus in the zygote. The zygote stated the first transverse division across the longer axis of the cell and produced a two-cell juvenile sporophyte, The second division transversely occurred near the one extreme of the juvenile sporophyte and produced a small cell named as “rhizoid original cell” which finally developed into rhizoids after several divisions. It took about 48 hours from the zygote to developed into multicellular germling with rhizoids through subsequent cell divisions. The mean length of Sargassum horneri germling was more than 3 mm and grew 2 leaflets within culture of 15 days. After 50 days of culture, these germlings grew up to 20 mm in the mean length and with 10 leaflets. During culture of the germlings, higher temperature and longer light length are of benefit to germling growth and increase of leaflet number. The germlings showed preferable growth at 21-24℃ under 40 μmol photons.m-2.s-1 and long-day (14L:10D).

Abstract:In order to deeply understand the effects of cryopreservation on the configuration of embryos, we chose the Eriocheir sinensis as the object, and observed the exterior shapes and interior structure of different developmental stages embryos after treatment with cryoprotectants and cryopreservation by means of microscope, slice and electron microscopy. Results showed that: (1) Cleavage embryos swelled clearly after treatment with vitrifying solutions by two-step methods, exterior shape of the embryos had no significant difference compared to the control group by three-step equilibration methods, some yolk overflowed from the inner cells and cells were damaged seriously after cryopreservation. (2) Exterior shape of gastrula stage embryos was similar to the control group after treatment with two-step equilibration methods, surface of gastrula stage embryo treated with cryoprotectants crinkled and shaped reticulation structure by scanning electron microscopy (SEM), white gobbet appeared in cells of embryos and fringe of cell was coarse and protuberant by transmission electron microscopy (TEM). After cryopreservation, color of embryos was pink, cell became opaque, the brim of cell membrane was blurry and shaped floss, segmental yolk was disintegrated into granule, the surface of embryos was sunken and wrinkled. (3) Cell membrane of embryos broke off, ice holes of different size appeared inside embryos, visible vacuoles appeared inside cells by slice observation. Ice holes in cells were very clear and some vacuoles appeared, about 80% mitochondria dissolved, breach of cells was very obvious by TEM. Exterior shape of the original zoea stage embryos had no difference compared to that of the control group after treatment with cryoprotectants by microscope and SEM. After cryopreservation, above 95% tissues shaped dispersion, partial yolk was disintegrated into granule, cell membrane of embryos broke off, ice holes appeared inside embryos. Surface of 90% embryos was sunken and wrinkled, but the cuticle of 10% embryos retained slick and intact by SEM. The results implied that the original zoea stage of embryos was the appropriate stage for cryopreservation.

Abstract:Research was made in this paper on the moisture, lipid content and fatty acid composition of muscle, liver and ovary of adult female Tridentiger trigonocephalus collected from the Yangtze Estuary at Ⅴ stage of ovary development. The results indicated that: (1) The moisture content in muscle, liver and ovary was reduced successively, and the value was significantly different among these three tissues (P<0.05). The total lipid content in these three tissues was (1.32%±0.08%), (7.75%±0.38%), and (26.73%±0.59%), respectively. There was significant difference in total lipid content among these three tissues, and the highest was in ovary, followed by liver, and the lowest was in muscle. (2) The content of SFA in muscle was significant higher than that in liver and ovary. There was significant difference in SFA content among three tissues (P<0.05). About the MUFA, C16:1 content of liver is the highest. The C16:1 content in muscle, liver and ovary were (11.90%±0.71%), (15.28%±2.42%) and (9.49%±0.37%) respectively, and there was significant difference among these three tissues (P<0.05). The content of PUFA, w3PUFA, w6PUFA in ovary was significantly higher than that in muscle and liver (P<0.05), but showed no significant difference between muscle and liver (P>0.05). The total content of EPA and DHA in muscle, liver and ovary were increased successively. The total content of EPA and DHA in these three tissues was (30.17%±1.02%), (30.53%±0.50%) and (34.33%±0.71%), respectively. The content of EPA and DHA in ovary was significantly higher than that in muscle and liver (P<0.05), but showed no significant difference between muscle and liver (P>0.05). The ratio of EPA to DHA (EPA/DHA) in these three tissues was 1.50, 1.75 and 1.59 respectively, and the ratio of total w3 polyunsaturated fatty acids to total w6 polyunsaturated fatty acids (∑w3PUFA/∑w6PUFA) in these three tissues was 6.44, 8.05 and 7.00, respectively. The ratios of EPA/DHA and ∑w3PUFA/∑w6PUFA were highest in liver, followed by ovary, and the lowest was in muscle.

Abstract:To investigate the effect of meal size on postprandial metabolic response and excess post-exercise oxygen consumption (EPOC) in juvenile rock carp (Procypris rabaudi)[( 13.05±0.17) g, n=44], experimental fish were lightly anaesthetized and force-fed with compound feed (meal sizes: 0%, 0.5%, 1% and 2% body weight) at (25 ±0.5)℃. After diet offered, oxygen consumption rates at different intervals were measured. Variables of postprandial metabolic and EPOC responses were calculated. The results of present study showed that resting metabolic rates (RMR) were not significantly different among all groups. The postprandial metabolic rate first increased and then slowly decreased to pre-fed level. The time to peak metabolic rate and the energy expended on Specific dynamic action (SDA) in 0.5% and 1% meal size groups were lower than that of 2% meal size group (P<0.05). The peak metabolic rates (PMR) and the SDA coefficients were not significantly different among 0.5%, 1% and 2% meal size groups. Pre-exercise metabolic rate in feeding group was significantly higher than that of fasting group (P<0.05). Peak post-exercise metabolic rate, metabolic rate increment and excess post-exercise oxygen consumption magnitude were not significantly different between feeding group and fasting group. The maximum metabolic rate (MMR) and MMR/RMR were significantly higher than PMR and PMR/RMR (P<0.05). The fish fulfilled the increased energy demand during digestive process by means of prolonged SDA duration with the increase of meal size. EPOC was not influenced by feeding in the fish.

Abstract:Turbot (Scophthalmus maximus), a flatfish of deep water species, is a high-nutrition and economic-valued species and currently cultured widely in China. In recent years, however, serious germ plasm degeneration has come into being due to the lack of the long-term and effective broodstock management programmes, production of farmed turbot became highly unstable and total output declined gradually. Therefore, large-scale family selection programs recurring to PIT tag have been used to initiate the genetic improvement of turbot since national eleventh five-year plan by the Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Science. At present，F₂ population has been finished. In order to obtain new strains (or new varieties) and the extension of fine families,it was highly important, in the process of selective breeding, to obtain fine families with universality and fine families with exclusiveness. Thus, we carried out genotype-environment interaction analysis. In this paper, ten families from turbot selective breeding F₂ were dispatched in randomized block design to five farms in different locations (Liaoning, Jiangsu, Fujian, Shandong-1, Shandong-2) representing a wide variety of environmental conditions and data of body weight were collected. AMMI (Additive Main and Multiplicative Interaction) Model was used to analyze data collected. The results showed that G×E interaction for body weight was significantly different (P< 0.01) and G×E effects on body weight was higher than those of families genotype. The former was equal to 1.44 times of the latter. The yield of family G₅ and G₈ was comparatively high (844.796 g and 868.888 g) and the stability parameter of the two families was the lowest (1.154 975 and 2.668 016). Obviously, family G₅ and G₈ had a high and stable yield and wide adaptability and the two kinds of genotypes were beneficial to selective breeding of new variety (or new strain). Five test locations were divided into three environment groups , i.e., Group E₃, Group E₅ and Group E₁-E₂-E₄, at the same time, family G₆, G₁₀ and G₂ should be dispatched to the environment Groups E₃, E₅, E₁-E₂-E₄, respectively, based on “Which- won- where” view of the AMMI biplot (the yield of family G₆, G₁₀ and G₂: 851.768 g, 911.664 g and 784.764 g). The conclusion of the study can provide theoretic basis for selective breeding of new strains (or new varieties) and the extension of fine families.

Abstract:The abalone Haliotis diversicolor supertexta is the most important aquatic species in many marine farms in China. For the purpose of qualitative observation on the variation of immune defense and natural resistance of animals, the abalones were put into waters with different dissolved oxygen and some immune effectors involved in defense were detected. In this paper the immune response of the abalone and susceptibility to pathogen Vibrio parahaemolyticus under hypoxia stress condition were described. The abalones with an average body weight (14.25±2.21) g could tolerate 120 hours for exposure to a hypoxic condition when dissolved oxygen was reduced from (7.49?0.14) mg/L to( 2.53?0.16) mg/L without onset mortality occured at a water temperature (22.1 ?1.3) °C, and a salinity level of 30.72?0.54, and pH 8.20?0.14, but they suffered 91.11%?7.70% cumulative mortality rate which was 80% higher than the control animals due to being chal-lenged with V. parahaemolyticus at a dose of 5.0?10⁵ cells per abalone, and a clearance efficiency in the haemolymph of H. diversicolor supertexta decreased to -(3 340.47% ? 298.57)% inhibition rate. Obviously, the resistance of the abalones to V. parahaemolyticus infection decreaced and the susceptivity inceassed correspondingly under the hypoxic stress above, in which the total haemocytes counts (THC) and percentage of phagocytosis and the amount of superoxide anion (O₂^- ) produced by respiratory burst decreased by 30.62%?4.87%, 62.77%?5.79%, and 22.21%?5.89% respectively. That intracellular MPO activity and CAT activity went up from 9.63%?7.59% to 22.90%? 13.73% and 7.68?6.83% to 56.28%?13.96% respectively while dissolved oxygen reduced from (7.49? 0.14) mg/L to (2.53?0.16) mg/L suggests that the intracellular oxidation introduced by hypoxic stress response intensified and there must be much more oxyradicals. The trial abalones of H. diversicolor supertexta possessed a cumulative mortality rate of 37.78?3.85% and a haemolymph inhibition rate of ?(883.56%?123.22)%, and the maximal downtrends of 12.51%?6.59%, 21.90%?15.84%, 12.93%?5.74)% in THC and percentage of phagocytosis and the amount of O2- production respectively, and a variation of MPO activity ranges from ?(10.61%?4.20%) to 7.13%?6.45% and CAT activity from ?(5.17%?18.08%) to 16.26%?10.85% while not only dissolved oxygen went down from (7.49?0.14) mg/L to (4.51?0.12) mg/L but also infection with V. parahaemolyticus occurred due to the obvious hypoxic stress.

Abstract:Using a population including 92 F₁ individuals obtained from the cross olive flounder from Japan ×olive flounder from Korea as the segregating population, genetic linkage maps of flounder were constructed using the SSR marker by joinmap4.0 software .A total of 221 SSR markers were fixed to the genetic linkage map. 178 SSR markers were linked to 22 linkage groups in female map and 194 SSR markers are linked to23 linkage groups in male map. The lengths of the female and male maps are 599.0 cM and 693.4 cM and covered 76.27% and 78.82% of the genome, respectively. Principal component analysis was handled with three sets of data, overall length, weight and body depth.1 set of data that can explain 89.6% of the three traits was obtained, which was named growth-trait, GT of flounder. Based on the linkage maps, trait- marker regression and complexity interval mapping were analyzed to fix QTLs related to growth traits by WinQTLCart 2.5 software, the experiential LOD-value of 2.5 was the threshold value of existing QTLs. Three QTLs related to growth traits were obtained from this research , qGT-f4,qGT-m20 and qGT-f20, and the variance explained by the three loci were 27.60%, 13.74%, 10.27%, respectively. Twenty-two SSR markers related to growth traits (P<0.05) were obtained from trait- marker regression analyzing. The variance explained by single SSR, ranged from 3.70% to 11.26%. The six markers, scaffold558_51720, scaffold558_26183, scaffold903_69232, scaffold485_47120, scaffold1262_77386 and scaffold809_65154 were highly significantly ( P< 0.01) correlated with growth traits, and the variance explained by the six were 10.42%,7.31%,10.07%,10.07%,8.39%,11.26% respectively.

Abstract:The aim is to prepare a kind of sodium alginate microcapsules which could slowly release fish allergens. The spherical alginate microcapsules were prepared by the ionotropic gelation method and the microcapsules were formed by adding sodium alginate into aqueous solution containing calcium chloride. The prepared microcapsules were characterized by FTIR, DSC and SEM methods. The releasing mechanism of parvalbumin from the microcapsules was established based on equation fitting of release kinetics model. Parvalbumin could be embedded into alginate microcapsules. The entrapment efficiency was 69.24% while the loading ratio was 21.06%. The surface of microcapsules which had plenty of tiny holes was rough. The result of protein release in vitro showed that parvalbumin released rapidly in the first 5 hours, and then gradually achieved maximum. The release kinetics model suited Higuchi equation and Ritger-Peppas equation well. Fish allergen could be entrapped by sodium alginate, meanwhile allergen controlled-release was achieved. The mechanism fits with skeleton erosion in addition to protein diffusion mechanism.

Abstract:Parvalbumin (PV) is the major allergen of fish species. So far, research concerning fish allergy has been focused mainly on marine fish. China is the largest consumer and producer of freshwater fish in the world, and many people suffered from allergy when consuming freshwater fish. Therefore, figuring out the molecular characters of PV from freshwater fish would be important. In this study, four gene sequences of PV isoforms were amplified and cloned from crucian carp and mandarin fish by RT-PCR, with two genes from each species. All the four genes were 330 bp in length, encoding 109 amino acid residues. The deduced molecular weight of them was approximately 11.6 ku, and isoelectric points were 4.45-4.69. The existence of amino acid residues of Ala-14, Leu-16, Cys-19, Phe-67, Gln-69 and Thr-79 suggested that all the sequences belonged to β-PV. The identity between the two sequences of crucian carp was 80.73 %, and was 83.49 % in mandarin fish. The identity between PVs from different fish species was higher than 75 % and the sequences of Ca²⁺ binding sites were highly conserved. Phylogenetic tree based on some PV amino acid residues revealed that PVs are clustered into two major clades, teleost fish and other vertebrates. PVs of teleost were clustered into orthologous groups, suggesting duplication of the PV genes before the speciation of teleost while after the speciation of fish. The tertiary structures of these four PVs were constructed using SWISS-MODEL. They all contain three helix-loop-helix motifs named EF-hand. Two domains next to the C terminal were Ca²⁺ binding sites. These results may provide a molecular basis for further study on the allergen of fish PVs.

Abstract:Edwardsiellosis caused by Edwardsiella tarda is one of the most serious diseases in the eel culture industry. Bacterial ghosts, which have native surface antigenic structures and can induce humoral and cellular immune response, have become candidate of vaccine development. To explore the feasibility of E. tarda ghost vaccine in eel, E. tarda ghosts were generated by the thermal controlled expression of the PhiX174 lysis gene E in present study. At the same time the morphology, lysis kinetics, lysis efficiency and preparation conditions were also studied. Holes were observed in Escherichia coli and E. tarda ghosts by scanning electron microscopy and the bacteria become withered due to the loss of bacterial content. The lysis kinetics in E. tarda were also compared with those in E.coli. Generation of ghosts in the transformants of E. coli and E. tarda carrying plasmid pBVlysisE was performed successfully by increasing the incubation temperature up to 42℃. Compared to E. coli, in which lysis was observed within 30 min and was completed 3 h after induction of E gene expression, onset of E. tarda lysis occurred 1 h after temperature elevation and the lysis process was completed 5 h after induction. At the end of the lysis process, the efficiency of ghost induction in non-lyophilized E. tarda was 99.99%, as the results of 5 replicate experiments showed. However, no bacterial growth was detected in lyophilized E. tarda and there is no obvious difference in bacterial morphology before and after lyophilization. The lysis kinetics and lysis efficiency had no difference between beginning of induction at OD600=0.4 and 0.6. Among LB, BHI and NB medium, LB medium is the best for preparation of E. tarda because in this medium the ghosts are more integrated and lysed completely. In the study we successfully constructed E. tarda ghosts and optimized their preparation conditions, which will provide the foundation for development of vaccine against edwardsiellosis in eel.

Abstract:Black is an important body color of Koi (Cyprinus carpio Koi) which is performed through melanin synthesized by melanocyte, and tyrosinase is an important rate-limiting enzyme in melanin synthesis. It's unclear of genetic mechanism of Koi body color. The present work obtained Koi tyrosinase (Tyr) gene sequence and investigated the expression of Tyr gene in different strains and tissues using semi-quantitative PCR, trying to reveal the relationship between the pigment control genes and the body color. The results showed 1779 bp of Tyr gene, including a 1608 bp open reading frame encoding 535 amino acids. Sequence analysis of cDNA and protein and phylogenetic analysis indicated that conservation of Tyr is higher in teleost than between teleost and other vertebrates. Semi-quantitative analysis showed the highest Tyr expression in the eye and black skin, intermediate in brain, red and yellow skin, and lowest in liver and heart. There was no significant difference of Tyr expression between the same tissues of eyes, liver, heart, brain from different Koi carps, but differentiated in the skins with the highest in black skin, followed by red and yellow skin and small amount in white skin. The different expression was related to tissue function. The role of tyrosinase in non-melanoma cells was unclear. It possibly exist multiple forms of tyrosinase, some of which is inhibited, or the xanthophores and erythrophores could be translated into functional melanocytes.

Abstract:Singapore grouper iridovirus (SGIV) was an important piscine infectious virus. The virus caused more than 90% mortality in grouper and resulted in heavy economic losses in grouper aquaculture. SGIV ICP46 was an immediate-early (IE) gene, may be associated with cell growth control and could contribute to virus replication. A leucine-rich nuclear export signal (NES) in SGIV ICP46 was predicted. To identify the function of the NES in protein translocation, three recombinant plasmids including pEGFP- ΔNESa (containing the fragment before NES) , pEGFP- ΔNESb (containing the fargment after NES) and pEGFP- ΔNESc (containing the complete ICP46 fragment without NES) were constructed and used to track the movement of the protein lacking the NES in GP (Grouper embryo) cells. As the results showed, in pEGFP-ICP46-transfected cells, the fluorescence signal was observed mainly in the cytoplasm, outside of the nucleus. However, in pEGFP-ICP46-ΔNES-transfected cells, the fluorescence signal was scattered throughout the whole cell. These results indicated that the NES is essential for the translocation of SGIV ICP46 from the nucleus to the cytoplasm.

Abstract:The accurate site for vitellogenin synthesis was investigated in two representative shrimp species Litopenaeus vannamei and Macrobrachium rosenbergii with real-time PCR in this experiment. Based on histological observation, the ovarian development was divided into six stages in L. vannamei (oogonium proliferation, previtellogenic, primary vitellogenic, secondary vitellogenic, mature, and recovery stages) and five stages in M. rosenbergii (previtellogenic, primary vitellogenic, secondary vitellogenic, mature, and gravid stages). It was found that both L. vannamei and M. rosenbergii expressed Vg-mRNA in hepatopancreas and ovary. In L. vannamei, the relative quantity of Vg-mRNA expression of each developmental stage was 1.1, 5.9, 10.4, 26.9, 85.3, and 1.5 in ovary, and 1.3, 3.2, 7.1, 37.2, 51.6, and 1.0 respectively in hepatopancreas. In M. rosenbergii, the relative quantity of Vg-mRNA expression of hepatopancreas in each ovarian developmental stage was 3.4, 12.6, 15.2, 38.9, and 2.9 compared to ovary 1.0, 1.3, 1.7, 4.8, and 1.5, respectively. In all examined shrimps the Vg-mRNA expression decreased sharply to the minimum at the last development stage.

Abstract:Infectious pancreatic necrosis virus (IPNV) is a major viral pathogen of salmonid fish and causes serious economic losses to salmonid aquaculture. We amplified a 616 bp epitope of the VP2 gene from recent IPNV-ZYX isolated from farmed rainbow trout (Oncorhynchus mykiss) of China, and cloned into pCold TF vector(designated as pCold TF-VP2 COE). The expression of recombinant plasmid pCold TF-VP2 COE in E. coli BL21(DE3) was induced and detected by SDS-PAGE analysis. The predicted molecular weight for recombinant VP2 COE protein was approximately 78 ku and this was confirmed in this study. The fusion protein was purified with ProBond^TM resin from the suspension centrifuged and the antisera against VP2 COE protein were produced. The prepared antisera reacted specifically with IPNV(ATCC VR-1318)antigen by indirect ELISA. The antisera against VP2 COE protein had OD values at least twice that obtained for the negative control serum at a dilution of 1:12 800. IFA showed specific reaction of the antisera against VP2 COE protein with liver samples of rainbow trout naturally infected with IPNV in Heilongjiang province. The results showed that the expressed VP2 COE protein was immunogenical and antigenical which was the same as the natural IPNV VP2 protein. All this work established a foundation for further study on vaccine and rapid diagnosis of IPNV.

Abstract:In this study, the genetic diversity and genetic structure of two spawning season cohorts of Ommastrephes bartramii in North Pacific Ocean were analyzed based on mtDNA COⅠand Cytb gene sequence analysis. 600bp of COⅠpartial sequences and 481bp of Cytb partial sequences were obtained by using PCR amplification and sequencing. The result revealed that the number of haplotype, haplotype diversities, nucleotide diversities and average nucleotide differences in COⅠand Cytb sequences were 24, 0.729?0.033, 0.00570?0.00325, 3.421 and 28, 0.852?0.016, 0.00645?0.00373, 3.101 respectively. All 7 populations were characterized by higher haplotype diversity and lower nucleotide diversity. A shallow topology of haplotype neighbor-joining (NJ) tree showed no phylogeographic structure among 7 populations. Analysis of molecular variance (AMOVA) and the fixation indices (Fst) of 7 populations showed that the genetic variance mainly came from individuals within populations, and no genetic differentiations between populations were detected from our study. It was supposed that extensive gene exchange between two spawning season cohorts was attributed to continuity of spawning ground and hatching date in temporal and spatial distribution, higher swimming speed of Ommastrephes bartramii individuals and influence of sea currents.

Abstract:For the purpose of reconstructing the fish protein with high moisture and making meat analog, the central composite design and response surface method were used. Five extrusion process parameters including feed moisture, barrel temperature, screw speed, feed rate and motor rate of the cooling die were taken as the dependent factors, while fibration degree, hardness, springiness, chewiness and color of the meat analogs as independent parameters. Firstly, the extrudate obtained have well-defined fiber formation along the axial direction and resemble natural meat in springiness, visual and taste sensation. The results also indicated that the feed moisture had very distinct influence(P<0.01) on fibration degree, hardness and chewiness, and significant impact (P<0.05) on L^* and a^* of the color. The increase of the feed moisture will lead to the decrease of fiberation degree, hardness, chewiness and a^* and the improvement of L^*. The barrel temperature affected chewiness markedly while it affected hardness, a^* and b^* significantly. Higher barrel temperature will increase the chewiness and a^* and the hardness increases first and then decreases. Feed rate also has remarkble effect on fibration degree.

Abstract:Based on the data collected from bottom trawl surveys in Yellow Sea and Bohai Sea in May 2010, the community structure of crustaceans in different regions of Yellow Sea and Bohai Sea were analyzed. We collected a total of 32 crustacean species, including 18 species of shrimp,13 species of crab, and 1 species of squill. The dominant species changed between different regions. The Crangon affinis which was the most important crustacean species in ecosystem was dominant species in all regions of Yellow Sea and Bohai Sea. We studied the composition of average relative density of crustaceans, found that the biomass of crab was highest in all regions, the average relative biomass of crab was 2.97 kg/h, the individual number of shrimp was highest in all regions, the average value was 1825ind/h. We also studied the spatial distribution of crustaceans, found that the sequence by biomass was Northern Yellow Sea >Southern Yellow Sea >Middle Yellow Sea >Bohai Sea. The diversity of crustaceans in Yellow Sea and Bohai Sea was analyzed, the results suggested that the diversity index were highest in Southern Yellow Sea, lowest in Middle Yellow Sea, no matter by biomass or by abundance. The community similarity was also analyzed, the results suggested that the community similarity index was relatively higher between adjacent waters.

Abstract:The dielectric properties of tilapia at different parts (anterior, middle, tails, belly), different temperatures (10~90 °C), different frequencies (300~3 000 MHz ), and different moisture contents (3.8590~ 0.1161 g/g d.b. (dry basis)) were determined using the coaxial line method. The dielectric constants of tilapia among four parts were similar, the greatest difference was 4.91, and the average difference was 2.37. Four parts of tilapia were the same in variation trend of dielectric loss, but the value of belly was lower than that of others. This is perhaps the fact that It is maybe the fat content of belly was higher than other parts. However, due to the differences were small, the effects of components on dielectric loss can be ignored. For this reason, the average of dielectric properties values(ε^?, ε^?) for four parts were employed to investigate the effect of temperature, frequency, moisture content on tilapia dielectric properties valuse (ε^?, ε^?). In addition, the dielectric constant of tilapia decreased with the increase of frequency and temperature, and decreased along with the decrease of moisture content. However, with the increase of frequency, the dielectric loss decreased to a minimum (2 300 MHz) and then increased. When the frequency was lower than 2 300 MHz, dielectric loss increased as the temperature increased, and when the frequency was higher than 2 300 MHz, it was contrary. The dielectric loss also decreased with the decrease of moisture content. Moreover, the penetration depth[Frequency: 915, 2 450 MHz; Temperature: 10-90 °C; Moisture content: 3.8590-0.1161 g/g d.b. (dry basis)] of tilapia was calculated, regression analysis was employed to develop polynomial equations of dielectric properties and penetration depth. The predicted values and the experimental values were well correlated.

Abstract:Through the commercial fishing independent trawlers catch sampling, a total of 794 individuals of Asian moon scallop, Amusiu pleuronectes were collected quarterly from August 2010 to May 2011 in the Beibu Gulf, South China Sea. By biological measurement and resource statistics, the relationship of modality parameters and weight parameters, and the growth and the resource distribution were studied. Results showed that the partial correlation effects of four modality parameters on body weights and adductor weights were as follow in sequence: shell lengths > shell widths > shell heights > hinge ling lengths. Shell lengths, shell widths and shell heights are the most important parameters. Moreover, the mollusk and adductor muscle accounted for almost half of the total body weight and mollusk weight respectively. In summer,the mainly growth was the shell. In spring, the mainly growth was the mollusk part. The resource mainly distributed in the areas of 20?15′N~21?15′N, 108?~109?′E, with the water depth ranging from 20m to 50m and the bottom covered with mud and sand. The spatial distribution showed distinct regularity character. It progressively increased from the south to the north at the latitude, and increased firstly and then decreases from west to east at the longitude. Seasonal variations were also recorded with the peak of summer and the value from spring to winter was 8.72 kg/km2, 13.93 kg/km2, 9.82kg/km2 and 5.90 kg/km2 respectively. Statistics demonstrated that sea surface temperature was the most important environmental factors and has a positive correlation with the average resources density (r=0.972), while salinity and plankton did not show linear correlations.