Abstract:During 2009/2010 and 2010/2011 fishing seasons, Antarctic krill Euphausia superba Dana from the south Atlantic Ocean was harvested by Chinese commercial fishery vessels in the CCAMLR subarea 48.1 near the South Shetland Islands and CCAMLR subarea 48.2 near the South Orkney Islands, respectively. The length-frequency and sex ratio of krill collected in both fishing seasons were analyzed to estimate its growth, age structure, and evaluate potential temporal spatial variations of its spawning season. Based on the results of length frequency fitting mixture distribution, five age groups (1+~5+) were observed in the krill population. The age structure and sex ratio of krill varied in the two fishing seasons and subareas. In the waters near the South Shetland Islands of subarea 48.1, E. superba population was dominanted by individuals at age 5+ in January, 2010 and December, 2011. In the two months, gravid female were abundant and consisted over 40 percent of all krill numbers. Gravid females were between age 3+~5+ and dominated by those of age 5+. In contrast, in the waters near the South Orkney Islands of the subarea 48.2, E. superba population was still dominated by individuals of age 5+ in February, 2010, yet subsequently by those of age 3+ in February, March and April, 2011. Although gravid females of age 5+ were observed, their proportions decreased only about 15% in February, 2010 and less than 1% from February to April, 2011. Monthly observation during February, March and April, 2011 showed that it tended to be fewer gravid individuals, more unimodal age structure and increased sex ratio.In addition, the krill growth rate decreased with month and was negative value in March and April. Based on the above results, it could be inferred that in subarea 48.2，E. superba spawning peak in 2010/2011 fishing season should be earlier than February, 2011, while spawning remained in that month of 2009/2010 fishing season.

Abstract:Nikon E200 microscope was used to observe the embryonic development of Centropristis striata Linnaeus. Detailed changes from the fertilized egg to the newly hatched fish, and morphological characteristics of 26 specific developmental stages were described. The results showed that fertilized eggs of C. striata Linnaeus were free-floating and spherical, at an average diameter of 0.950±0.039mm; Embryonic development C. striata Linnaeus experienced six main stages including cleavage, blastocyst, gastrulation, neurula embryo, organogenesis and hatching stage. The results showed that, at water temperatures of 20~20.5℃,salinity 28~32, DO≥5mg/L, and pH 7.6～8.4,fertilized eggs of C. striata maintained in cages with slight areation were hatched in 47 h, and yolk-sac in the larvae disappeared after 2 days.

Abstract:Seven microsatellite loci were identified in the GH, GHRH and PACAP genes of Cynoglossus semilaevis, and were used as polymorphic markers to analyze the genetic diversity and genetic structure of two wild populations (BS and YS) and a cultured population (HS). The results revealed that no genetic polymorphism was detected in three loci out of seven. The numbers of alleles in the other four loci ranged from 2 to 37, with an average of 9.5，and the numbers of effective alleles ranged from 2 to 28.9, with an average of 8.4. The observed and expected heterozygosities ranged from 0.514 5 to 0.773 8 and from 0.569 0 to 0.867 1, respectively. The average polymorphism information content per locus ranged from 0.482 9 to 0.831 4. The results of pairwise FST and individual distribution analysis demonstrated that there was no significant difference between the wild populations, while significant differences were observed between the wild and the cultured populations. Moreover, based on the distribution of alleles and diploid genotypes, no significant difference was observed between female and male in any of the three populations.

Abstract:This study described the developmental characteristics of external apparatus during early life stages of bluefin leatherjacket, Thamnaconus modestus. The developmental morphological characteristics of 11 external apparatus were recorded and described in detail. 1) Mouth: opened at 2-3 dph(days post hatching), then grew continuously except at the stagnation stage (24-28 dph). 2) Eyes: pigment appeared at 1 dph, choroids formed and the pupil was black at 3 dph, sclera formed at 4 dph, rim of the eye appeared at 14 dph, and the eye form was same with adults at 40 dph basically. 3) First dorsal fin spine: anlage appeared at 3 dph, fin spine formed initially at 7-8 dph, protruded out of body at 10 dph, development finished roughly at 14 dph, and the shape was the same with adult at 60 dph basically. 4) Girdles and pelvic fin spine: Girdles appeared at 5 dph, pelvic fin spine grew fast at 5-7 dph, and shunk from 10 dph, all pelvic fin spine off at 30 dph. The shape of girdles was the same with adult at 60 dph. 5) Pectoral fin: fin membrane thickened and the fin ray formed at 15 dph, developed completely at 30 dph. 6) Dorsal fin and anal fin: fin suspensorium and fin ray appeared at 14 dph, fin ray developed completely at 24 dph, and the shape at 60 dph was the same with adult’s. 7) Caudal peduncle: caudal vertebra was straight until 14dph, some fin ray anlage appeared under the tail end of notochord at 16 dph. The tail end of notochord up-curved, fin ray developed completely and sub-section at 16-24 dph. Caudal fin turned into rotundity at 50 dph. 8) Scales and skin: epidermis thickened at 8dph, the compact epidermis appeared first at head, full body covered by scales at 40dph, turned into withy leathery epidermis. 9) Abdomen and splanchnic zone: yolk-sac was absorbed, anus and the first intestinal loop formed at 2 dph, oil ball disappeared and the fish larvae fed on the oyster larvae. The anlages of liver, kidney and swim bladder appeared at 8-12 dph, and the three organs formed at 16 dph. Spleen formed at 18 dph. The growth curve of total height, pre-anus length, eye length and side length of lower jaw during 0-75 dph were also described in the present study.

Abstract:Since the Sox9 plays a pivotal role during ovary development, the importance of two forms of Sox9 in the process of ovarian recrudescence in yellow catfish Pelteobagrus fulvidraco was analyzed. Tissue distribution pattern showed preferential expression of Sox9a2 in brain and ovary (brain>ovary), and trace amounts was detected in stomach, while the extensive expression of Sox9a1 was observed in several tissues. A semi-quantitative RT PCR was developed to measure the mRNA levels. The high transcript levels of both isoforms in ovary were found in the reproductive phase of ovarian cycle, with the highest level in stage Ⅲ for Sox9a1 and Ⅴ for Sox9a2.While the level of Sox9 in brain dropped significantly from stage Ⅱ. The phase-dependent rising of Sox9a2 and Estradiol-17β (E2) in fish exposed to higher temperature revealed the stimulatory role of heat stress. Gene expression of Sox9a1 in ovary was not consistent with E2 level in serum of fish exposed to higher temperature. Sox9 expression in brain was contrary to the level of E2 in stage Ⅱ. The expression level of Sox9a1 and Sox9a2 were closely related to level of serum E2 in stage Ⅲ-Ⅵ. Results demonstrated Sox9a2 in ovary played a crucial role in the reproductive cycle of female yellow catfish, and Sox9a1 in ovary was not involved in controlling the reproductive cycle. In addition, we infered that temperature can affect the negative regulation between Sox9 in brain and E2, while the mechanism needs further research.

Abstract:By calculating and analyzing the average gathered number of unit volume (AGNUV) and the mean attractive rate (MAR) on ten types of artificial substrates and 8 distributional areas, the inhabitation taxis and selection of Apostichopus japonicus was estimated. The results showed that the attractive effect of 10 substrates was in the following descending order：big poly-arris tile, stone, three-hole brick, small poly-arris tile, U-shaped tile, eddy abnormity tile, triangle tile, cage substrate, sunshade net and bamboo substrate. There was significant difference between the big poly-arris tile and eddy abnormity tile, triangle tile, cage substrate, sunshade net and bamboo substrate. It also showed that the MAR of pool edge angle (21.02%) was higher than that of pool wall (8.23%) and pool bottom surface (15.68%), while the MAR underneath and inside of substrate was respectively higher than that of upside and surface. In addition, the experimental test approved the following: (1) The big poly-arris tile had the best performance in the attractive effect; (2) The sea cucumber had an habit that they tended to stay on different location at different time; (3) Stone, cage substrate and sunshade net were not suitable for sea cucumber culture. The attractive effect of several substrates was compared and analyzed in this study.

Abstract:Heavy metal pollution in filter-feeding bivalves has received more and more attentions. With regard to the studies in this field, the two-compartment kinetic model is a new mode for rapid determination of bioconcentration factor（BCF）. With a mixed solution of six heavy metals(Cu, Zn, Pb, Cd, Hg,and As), kinetic parameters of bioconcentertion in Ruditapes philippinarum were measured using a two compartment kinetic model. A semi static system was maintained throughout a 15 day exposure period in different concentrations of heavy metals at 15-5±2℃. During the uptake phase, water was changed every day, sufficient to maintain relatively constant concentrations of heavy metals. At 0d, 2d, 5d, 8d, 11d and 15d, R. philippinarum was sampled, and the samples were frozen immediately for the following analysis. Kinetic parameters of bioconcentration were obtained from the two-compartment model by nonlinear curve fitting, including uptake rate constant (k1), elimination rate constant (k2) and bioconcentration factor. The results showed that in the high and medium concentration group the BCF of Cu, Zn, Pb, and Cd in R. philippinarum were 66.99, 18.49, 57.11, 25.81 and 72.46, 35.72, 117.91, 41.83, respectively. Hg, As, and the low concentration group of Cu, Zn, Pb, Cd enrichment regularity was not obvious. The uptake rate constant and bioconcentration factor decreased with the increase of heavy metal exposure concentration in ambient seawater. The ability of accummlation of Cu, Zn, Pb, Cd, Hg, and As in R. philippinarum were Pb>Cu>Cd>Zn. χ2 and F tests for goodness of fit test showed that the fitting data of χ2 value were less than 0.71(critical value), which suggests that the fitting goodness was acceptable. Two-compartment kinetic model could fit well the accumulation of heavy metals in R. philippinarum.

Abstract:Dark-thin syndrome often occurred at stages of larval turbot Scophthalmus maximus, causing lower metamorphosis and more than 80% of mortality. One bacterial strain was isolated from the diseased larvae, and it was confirmed to be the pathogen causing the disease through artificial infection tests. The pathogenic bacterium was identified as Vibrio splendidus by conventional physiological and biochemical tests as well as 16S rDNA sequence analysis. In addition, histopathological studies demonstrated that the bacterium could cause infectious changes in the liver, kidney, spleen, intestine and brain. The effective components of 11 Chinese herbs were extracted respectively by the methond of decoction, and they were tested for the susceptibility against V.splendidus. The results showed that Galla chinensis and Radix pulsatillae had the best inhibitory effect on the bacterium, with minimal bactericidal concentration (MBC) of 25mg/ml. MBC for both Phellodendron chinense and Herba andrographitis was 50mg/ml. While Chinese angelica, Radix codonopsisand, Eucommia bark, Codex fraxini, Flos lnicerae, Boswellia carterii and Commiphora molmol had the weakest inhibition effect with MBC more than 100mg/ml. The preliminary tests indicated that G. chinensis and R. pulsatillae were good treatments by oral and immersion administration.

Abstract:In order to make the best use of the information on fishery resources derived from fishing vessels, a series of processing methods were probed to numericalize the pictorial image of the acoustic echogram taken from a commercial echo-sounder. The resulting methods were then applied to analyze the swarming characteristics of Antarctic krill Euphausia superba utilizing echogram image photos taken from a Chinese Antarctic krill fishing vessel. The thickness, gravity center and relative density were analyzed after a series of preprocessing including adjustment of shooting angle and luminance of the photos, and standardization of the RGB Triplets and binarization of each pixel. Results from 30 images showed that the mean thickness of these krill swarms ranged from 5.6 m to 55.8 m,and the median thickness and mean thickness were 25.7 m and 27.1 m, respectively. The gravity center of these swarms was found between depths of 40.0 m and 156.5 m, and the median depth and mean depth were 68.8 m and 77.3 m, respectively. There was an apparent diel variation in the swarming characteristics of Antarctic krill. the swarms were relatively thinner but krill densities were relatively high in day hours; and the opposite were true at night. This exercise provided an effective tool for the study of fishery resources using fishing vessels where only commercial echo-sounder is available.

Abstract:In order to evaluate the genetic diversity of sea cucumber Apostichopus japonicus and breed eugenic varieties, a CA microsatellite containing short fragment genomic DNA library of sea cucumber was constructed using the FIASCO(Fast Isolation by AFLP Sequences Containing Repeats)method. In 140 randomly selected and sequenced clones, 118 contained a CA repeat motif. According to Weber(1990) classification rules, the sequences were divided into three categories: 83 perfect repeat sequences without interruptions in the runs of CA or GT dinucleotides (70.4% of total), 30 imperfect repeat sequences with one or more interruptions in the run of repeats (25.4%), and 5 compound repeat sequences with adjacent tandem simple repeats of a different sequence (4.2%). Twenty pairs of primers were designed and used to investigate the polymorphism and genetic structure of wild A. japonicus collected from China(CH), Korea(KW, KE), Japan(JA) and Russia(RU). Cross amplification of twenty loci were also tested in Parastichopus parvimensis which were collected in USA(AM). The results demonstrated that all the markers were polymorphic and 16 loci had high polymorphism (PIC>0.5). The average observed and expected heterozygosities of the 20 loci were 0.39 and 0.69, respectively. In addition, a total of 231 alleles (102 effective alleles) were detected at 20 loci in the total samples and the alleles number of each locus ranges from 3 to 20 with average of 11.6. The Hardy-Weinberg Equilibrium (HWE) analysis showed that all the loci deviated from genetic equilibrium in the six populations and heterozygote deficiency occurred to different extent in total samples (Fis>0). Genetic identity of the five A. japonicus populations was 0.71, while the genetic identity between A. japonicus and P. parvimensis were quiet low. In the UPMGA tree, CH and KW populations formed a cluster, RU, JA and KE populations formed another cluster, while AM felt into a seperate cluster. The result of cluster analysis indicated that the clustering order had significant correlation with geographic distance.

Abstract:Partial sequences of COⅠ genes from 8 species of Scleractinian in Xuwen area,Guangdong Province, were amplified and sequenced, and the base ratio and variations were analyzed . The result indicated that the average G+C content of this region accounted for 41.60%，while the codon position 1 was the highest, in the range of 42.26%~44.05%(43.45% in average). The proportion of transition and transversion was 70.30% and 72.70% respectively in codon position 3. The phylogenetic trees were also constructed based on COⅠ genes of these 8 samples and other 20 Scleractinian species recorded in GenBank. According to the Neighbour-joining, minimum-evolution and maximum-likelihood trees, molecular systematics was slightly different from the morphological conclusion, which suggested that morphological classification may be limited by coral skeletons plasticity. Consequently, the COⅠgene is one of the auxiliary tools to classify the phylogeny of Scleractinia.

Abstract:The variation of amount and community composition of bacteria in the sea water and sediments of monoculture (Apostichopus japonicus) and co-culture systems (A. japonicus co-cultured with Gracilaria lemaneiformis) were evaluated. The total numbers of bacteria (2.14×106~4.27 ×106cells/ml) in the bottom water of the monoculture and co-culture systems increased during the period of the experiment. The bacteria numbers in the surface sediments ranged from 1.55 ×108 to 3.39 ×108cells/gdw in the systems, which were much higher than those in the bottom sea water. UPMGA cluster analysis of DGGE fingerprint from sediments revealed the bacterial community in the same sampling date had higher similarity than those in different sampling dates. Phylogenetic analysis showed that the dominant bacteria of the sediment in the monoculture and co-culture systems belong to α-proteobacteria, γ-proteobacteria, δ-proteobacteria and bacteroidetes.

Abstract:Nannochloropsis oculata，Cryptomonas erosa and Oscillatoria chlorine were seperately or co-cultured in inorganic culture solutions,and the consumption of nitrogen and phosphorus during the culturing was analyzed. The results showed that the absorption ability of O.chlorine on nitrogen and phosphorus was the highest, and that of C.erosa was the lowest. The nitrogen consumption by O.chlorine, N. oculata, and C. erosa were 13.496, 7.533, and 6.739 mg/L respectively at the tenth day, and that of phosphorus were 2.165, 0.581, and 0.510 mg/L, respectively. The effect of the microalgae co-culturing was investigated by the path analysis method. The results showed that the absorption of nitrogen and phosphorus by them both increased, indicating that the interaction of N. oculata and O. chlorine was positive. When N. oculata and C. erosa were co-cultured, N. oculata played a dominant role in utilization of nitrogen and phosphorus. However, the nitrogen and phospborus utilization ability of C. erosa was significantly (P<0.05) inhibited by O. chlorine.

Abstract:The effect of low-temperature, MS-222 on ammonia excretion rate of Carp and percentage of ammonia-nitrogen removal on zeolite modified by salt were studied using water static seal-type detector by self-made aiming at extending time of keeping Carp alive during the transportation and storage. The results showed that the ammonia excretion rate of Carp decreased with water temperature decreasing at 10~30℃（P<0.01）,it at 30℃ was 5.11~6.44 times that at the low 10℃, their relationships with temperature could be represented by polynomial Y=-c+b1X+a1X2, their interaction of temperature and body weight had significant effects on the ammonia excretion rate (P<0.01). The ammonia excretion rate of Carp decreased with MS-222 concentration increasing at 0.80 mg/L（P<0.01）, it at MS-222 concentration of 80ppm decreased by 54.1%~51.1% comparing with the control group, the relationship with MS-222 concentration could be represented by polynomial Y=-c-b1X+a1X2. The zeolite soaked by NaCl could effectively remove ammonia in water,percentage of ammonia removal was gradually stable when the NaCl concentration of was greater than 60 g/L, percentage of ammonia removal reached the maximum when the NaCl concentration was at 80 g/L, and modified zeolite by salt was able to remove efficiently ammonia-nitrogen in water continuously within 24 h.

Abstract:A 10-week feeding trial was conducted to study the effects of soybean meal supplemented replacement by peanut meal supplemented with lysine and methionine on growth, apparent digestibility coefficient (ADC) and body composition of juvenile hybrid tilapia (Oreochromis niloticus×O. aureus) at initial mean body weight of 7.30±0.12 g, which were stocked in floating net cages suspended in an earthen pond. Five isonitrogenous and isoenergetic experiment diets (D1~D5) were formulated with low fish meal content (2%). D1 was used as control containing 30% soybean meal (SBM). D2 was formulated with peanut meal (PNM) replacing 50% SBM protein. D3~D5 were formulated on the basis of D2 supplemented with crystalline lysine (0.25%)+methionine (0.05%), microencapsulated lysine (0.25%) + methionine (0.05%) or microencapsulated lysine (0.50%)+methionine (0.10%), respectively. Chromic oxide (0.5%) was added as an external indicator to determine the ADC for nutrient or energy of the experimental diets. The results showed that no significant difference (P>0.05) were found among survival rates of the experimental diets. Specific growth rate (SGR) had no significant differences (P>0.05) between the control and D5, which were significantly higher (P<0.05) than the other three diets, and D2 resulted in the lowest SGR. Fish fed D2 and D3 had significantly higher (P<0.05) feed conversion ratio than D5 and the control. Fish fed D5 and the control had significantly higher (P<0.05) protein efficiency ratio than D2 and D3. Condition factor showed no significant difference (P>0.05) among the D4, D5 and the control, which were significantly higher than D2 and D3 (P<0.05). There were no significant differences (P>0.05) in viscerasomatic index and hepato-somatic index between the experimental diets. ADCs of dry matter, crude lipid, gross energy and essential amino acid had no significant difference (P>0.05) among the experimental diets. ADC of crude protein had no significant difference (P>0.05) among the microencapsulated amino acid supplemented diets and the control, however, which were significantly higher (P<0.05) than D2. Whole-body proximate and essential amino acid composition of the fish were not affected by replacement of SBM with PNM or supplement of crystalline or microencapsulated lysine and methionine. Compared to crystalline amino acid, the results indicated that dietary microencapsulated lysine and methionine supplements obviously improved the growth performance of juvenile tilapia and the ADC of dietary protein under the conditions of this experiment.

Abstract:Turbot Scophthalmus maximus, a marine finfish with fast growth and strong tolerance to cold water temperature, is the most widely cultivated commercial flatfish around the world with the highest annual aquaculture production. From its introduction into China in 1992 to now, its aquaculture has developed into one of the dominant mariculture industries in China with an annual production of more than 60,000 tons. The progress and achievements on the industry development, seed production, selective breeding, culture modes, nutrition requirements and artificial feeds, disease prevention and control, processing and quality control, market and aquaculture economy during the past two decades, are reviewed. Further research and industry development priorities in turbot culture are also suggested. This paper also provides the necessary referential information for the development of turbot culture in China.