We applied surplus production model and delay difference model to analyze the data of the southern Atlantic albacore (Thunnus alalunga) stock. Results show that the delay difference model captured annual fluctuation of catch per unit effort (CPUE) better than the Schaefer model. Akaike information criterion (AIC) also reveals that delay difference model performed better. We calculated an 80% percentile confidence interval of maximum sustainable yield (MSY) of 21 756~23 408 t (median 22 490 t) and 26 116~28 959 t (median 27 520 t) by delay difference model and Schaefer model, respectively. Results of biological reference points show that the southern Atlantic albacore stock was in a good state before 1985 but had been overfished from 1985 to 2005;after that, it was rebuilt gradually but must be taken care of. The delay difference model gave more effective and conservative results than the surplus production model.

Based on the bottom trawl surveys in May of 2013, we investigated the community structure and biodiversity of nekton near Oufei Beach of Wenzhou by traditional diversity analysis, abundance-biomass comparison curves, clustering analysis and non-metric multidimensional scaling. A total of 87 species were collected, including 55 species of fish, 18 species of shrimps, 10 species of crabs and 4 species of cephalopods. The dominant species were Amblychaeturichthys hexanema, Pampus argenteus and Harpodon nehereus; the important species were Lateolabrax maculatus, Collichthys lucidus and other 15 species. The densities of nekton quantity and weight were 304.6×10³ ind · km^-2 and 365.8 kg · km^-2, respectively. Cluster analysis and non-metric multidimensional scaling (NMDS) analysis reveal that the nekton community could be spatially clustered into three groups. ANOSIM analysis shows very significant difference in nekton species composition among all groups (R=0.463~0.807). The abundance and biomass curves (ABC) indicate that the nekton community was seriously disturbed, and the fast-growing, small-sized and opportunistic r-strategist was dominant in the nekton community. The Shannon-Wiener diversity index (H′), Pielou evenness index (J′) and Margalef species richness index (D) ranged from 1.31 to 3.74, 0.33 to 0.78, and 1.80 to 5.81, respectively.

Based on the production data of the light falling-net fishing vessels in Xisha and Zhongsha sea area from 2006 to 2010 (March to May), we investigated the effect of moon phase on fishing rate of Symplectoteuthis oualaniensis based on general additive model (GAM). And the difference of the fishing days and the average daily catch between bright moonlight (8^th~22^nd, lunar calendar) and no-moonlight (23^rd~7^th, lunar calendar) were analyzed by ANOVA analysis. The results show that the effect of moon phase on average daily catch of S.oualaniensis was remarkable by GAM analysis in every year (P < 0.001). Significant difference was found in the fishing days (P=0.004 < 0.05) and average daily catch (P=0.024 < 0.05) in bright moonlight and no-moonlight, and the fishing days and average daily catch in bright moonlight were higher than those in no-moonlight.

According to the data collected from five micro-temperature and depth recorders (TDR-2050) attached along seine leadline of the tuna purse seiner named "JINHUI 7" operating in the Western and Central Pacific Ocean from February to May, 2014, we analyzed the relationship among rising depth, rising speed and rising time of different parts of tuna purse seine leadline. The results show that: 1) Rising speeds of different parts of leadline were different: the fastest rising speed was the middle part, followed by the back wing end and the bunt. 2) With increasing time, the rising depths of different parts of leadline increased steadily, and the tendency was firstly stable, then fluctuate considerably; the rising process of the bunt was similar with that of the back wing end. 3) The rising speeds of different parts of leadline increased gradually with increasing time, and the rising speeds fluctuated considerably. 4) The current speeds at the 70-m and 120-m layers had very significant impact on the rising speed (P < 0.01).

To evaluate the effect of the present breeding ways on genetic structure and breeding potential of Egyptian strain of Oreochromis niloticus, we analyzed the variation of mitochondrial DNA D-loop region in their three generations (80 individuals). The results show that: 1) The length of the region sequences was 552~555 bp; 52 variable sites and 12 haplotypes were detected. The average haplotype diversity was 0.569. 2) The nucleotide polymorphisms (P_i) of three generations were 0.021 9, 0.040 3 and 0.039 7, respectively, each generation showing high polymorphism in the mitochondrial genetic diversity. 3) F₁ generation contained five haplotypes; F₂ generation contained seven haplotypes; F₃ generation contained seven haplotypes. The three generations shared two haplotupes, and F₁ and F₂ generations shared a haplotype. The haplotypes of three generations crossed each other in the NJ tree and no unique clade of haplotype existed in each generation. It is concluded that there was no significant variation in genetic structure at the control region sequence in the three generations. The genetic information among three generations of O.niloticus was stable by the present breeding ways.

Juvenile Clarias gariepinus were reared at densities of 35 kg · m^-3, 65 kg · m^-3, 95 kg · m^-3 and 125 kg · m^-3 for 60 d. On 30^th and 60^th day, we measured the daily weight gain (DWG) and assayed the mRNA level of GH in pituitary by semi-quantitative RT-PCR. During 0~30 d breeding, the DWGs showed no significant difference between 35 kg · m^-3 and 65 kg m^-3 treatments as well as between 95 kg · m^-3 and 125 kg m^-3 treatments, but the DWGs were significantly higher at 35 kg · m^-3 and 65 kg · m^-3 treatments than those at 95 kg · m^-3 and 125 kg · m^-3 treatments. While on 30^th day, significant difference was not found in the GH mRNA level of pituitary between any two stocking densities. During 30~60 d breeding, the DWGs of 35 kg · m^-3 and 65 kg · m^-3 treatments were significantly higher than that of 125 kg · m^-3 treatment, there was no significant difference in DWG between the other two treatments. On 60^th day, the expressions of GH gene were significantly higher in 35 kg · m^-3 and 65 kg · m^-3 treatments than those in 95 kg · m^-3 and 125 kg · m^-3 treatments. The results indicate that there was no close correlation between DWG and mRNA level of GH in pituitary of juvenile C.gariepinus.

By designing primers and probe based on the conserved region of cfb gene of Streptococcus agalactiae isolated from tilapia, we developed a real-time fluorescent PCR assay for detection of S.agalactiae from tilapia tissue and verified the specificity, sensitivity and practicability of the assay. The standard and positive strains of S.agalactiae were positive, and all negative controls were negative. The minimum detectable concentration of S.agalactiae genome DNA was 3.42×10^-7 ng · μL^-1, and the detection limit of the assay was less than 10 cells per reaction system. The genome DNA samples of midgut, liver, spleen and kidney which were collected from tilapia artificially infected with S.agalactiae were tested by real-time PCR and were positive. The quantities of S.agalactiae detected in per μg DNA of tissue samples were 2.95×10³ cells, 2.45×10⁷ cells, 2.34×10³ cells and 4.54×10⁴ cells, respectively, and the controls were negative. The results show that the real-time quantitative PCR assay which we developed was accurate, specific and sensitive, and could detect S.agalactiae from various tilapia tissues rapidly. The method can be used for surveillance and prevention of S.agalactiae disease of tilapia.

We studied the attractive effects of the light source located in lock model on Hypophthalmichthys molitrix and Ctenopharyngodon idellus at different light intensities. The results show that the mean relative time aggregation rate [R(t)] in the dark area with light source was higher than the control group (no source). R(t) in the dark area in all light-source groups increased with increasing light intensity, and so did the distance between central location of fish group and location of light source. As for the H.molitrix, there was no obvious aggregation phenomenon (P>0.05) in all groups. Therefore, negative phototaxis of C.idellus could be used in driving the fish to the upstream by arranging light in the downstream of the chamber, but use of light trapping or driving H.molitrix are not feasible.

We investigated the survival, growth and changes of gills of juvenile milkfish (Chanos chanos) under freshwater acclimation. At the end of the 30-day experiment, the survival rate, weight gain rate and specific growth rate were recorded; the gills of juveniles were observed and compared with those cultured under freshwater without acclimation and sea water. The highest survival rate (100%), weight gain rate and specific growth rate of juveniles were obtained under freshwater acclimation. Large numbers of mitochondrion-rich cells were observed on branchial lamellae of juveniles in freshwater. It might be one of reasons for the high survival rate of juvenile C.chaos under condition of freshwater.

We applied the orthogonal experiment method of two factors and five levels to study the combined effects of temperature (16.0 ℃, 20.0℃, 24.0 ℃, 28.0 ℃, 32.0 ℃) and gravity (1.016 0, 1.020 0, 1.024 0, 1.028 0, 1.032 0) on survival and growth of juveniles in the laboratory. The results show that: 1) In the optimum gravity range, the suitable temperature range of juveniles' survival was 17.0~32.7 ℃; the optimum temperature range of survival was 24.0~28.0 ℃; the suitable temperature range of growth was 16.4~32.7 ℃; the optimum temperature range of growth was 24.0~30.0 ℃. 2) In the optimum temperature range, the suitable gravity range of juveniles' survival was 1.016 5~1.031 8;the optimum gravity of survival was 1.024 0;the suitable gravity range of growth was 1.016 3~1.031 8;the optimum gravity range of growth was 1.021 3~1.028 6. 3) There were combine effects between temperature and gravity. The suitable and optimum temperature as well as gravity ranges of juveniles decreased gradually with gradient moving to the two ends.

We studied the distribution of mucous and gastrin cells of digestive tract in Qinglong grouper (Epinephelus coioides ♀×E.lanceolatus ♂) juveniles by histochemistry (AB-PAS) and immunohistochemistry (SABC). Mucous cells in esophagus of juvenile were of TypeⅠ, TypeⅡ, TypeⅢ and TypeⅣ containing neutral and acidic mucoitin; mucous cells of TypeⅠ, TypeⅡ and Type Ⅲ were found in cardiac stomach; mucous cells of TypeⅠ, Type Ⅲ and Type Ⅳ were found in fundic stomach. Many mucous cells of TypeⅠ, and Type Ⅳ could be found around gastric gland, and only mucous cells of TypeⅠcontaining neutral mucointin was found in pyloric stomach. Pyloric caeca and intestines contained neutral and acidic mucointin. Mucous cells in the pyloric caeca were mostly of Type Ⅱ but less Type Ⅲ. Four types of mucous cells could all be observed in foregut, midgut and hindgut. The descending order of number of intestinal mucous cells was midgut>hindgut>foregut. Moreover, the study on the distribution of gastrin cells in the digestive tract by immunohistochemistry indicates that the gastrin cells were found in entire intestine and pyloric caeca but not in esophagus and stomach.

We analyzed the contents of seven metallic elements in prismatic layer and nacreous layer of shells from four shell color strains [(B), gold (G), red (R) and white (W)] in pearl oyster (Pinctada fucata) by ICP-AES. The Fe, K, Mg and Mn contents in prismatic layer were obviously higher than those in nacreous layer. The elements of Mg, Sr, K and Zn in prismatic layer of black shell were the lowest. Similarly, the Mn and Fe contents in prismatic layer of gold shell were lower than those in the other color shells, but Na had minimum content in red shell. Fe, Mg and Zn might have influence on the formation of red, gold and white shells. Besides, the nacreous layer of white shell had the lowest level in the content of analytical elements except Mg, which indicates that the white shell in pearl oysters is more likely to produce pearls of better quality.

The proliferation of Oscillatoria chlorine will release toxins which are harmful to prawn growth in the aquaculture ponds. We investigated the limiting concentrations of nitrogen (N), phosphorus (P) and iron (Fe³⁺) to the growth of O.chlorine as well as the effects of different N, P and Fe³⁺ concentrations on chlorophyll a content and dry weight of O.chlorine. The results show that N concentration < 0.06 mg·L^-1, P concentration < 9.93×10^-2 mg·L^-1 and >1.99 mg·L^-1, and Fe³⁺ concentration < 2.58×10^-2 mg·L^-1 and > 51.67 mg·L^-1, limited the increase of chlorophyll a content; N concentration < 12.36 mg·L^-1, P concentration < 9.93×10^-3 mg·L^-1 and the Fe³⁺ concentration < 5.16×10^-3 mg·L^-1 and > 51.67mg·L^-1, limited the increase of dry weight. The threshold concentrations of N, P and Fe³⁺for the growth of O.chlorine were 0.06 mg·L^-1, 9.93×10^-3 mg·L^-1 and 5.16×10^-3 mg·L^-1, respectively. The combined concentrations which limited the increase of chlorophyll a contents and dry weight of O.chlorine were 7.42 mg·L^-1 of N, 4.96×10^-2 mg·L^-1 of P and 5.16×10^-3 mg·L^-1 of Fe³⁺, respectively. Nitrogen had the strongest effect on chlorophyll a content and dry weight, followed by Fe³⁺ and P. It is suggested that the rapid proliferation of the O.chlorine might be controlled through water exchange or circulation to reduce the dissolved nitrogen content in the aquaculture ponds.

Grouper ranavirus infected many grouper species and caused severe mortality. We isolated a grouper iridovirus (genus Ranavirus) named GIV-R-SY1301 in Sanya by using cell culture, to study the tissue distribution of GIV-R-SY1301 in experimentally infected farmed Epinephelus lanceolatus by in situ hybridization and real-time PCR. The GIV-R-SY1301 was widespread in all tissues from infected fish.Strong hybridization signals were obtained from kidney and spleen, while intermediate intensity signals were observed in stomach, gill and liver. The weakest signals were obtained from heart and no signal was found in brain and eye. The real-time PCR results show that there were most viruses copies in spleen, kidney and heart (4.5×10⁴~6.85×10⁷ copies·μg^-1) DNA in different tissues, which was similar with the result of in situ hybridization.

We measured the Vibrio density in aquaculture water of Haliotis discus hannai by cultivation method, and investigated the main environmental factors including temperature, dissolved oxygen, potential of hydrogen, salinity, redox potential, nitrite, nitrate, ammonium and phosphate, so as to study the relationship between Vibrio quantity and main environmental factors. The results show that Vibrio density throughout the whole year varied from 0.2×10² cfu·mL^-1 to 6.03×10³ cfu·mL^-1(average 1.7×10³ cfu·mL^-1). When the temperature was less than or equal to 25 ℃, the Vibrio density had no correlation with any environmental factor; when the temperature was greater than 25 ℃, the Vibrio density had significant correlation with temperature (P < 0.05), redox potential (P < 0.01), nitrate (P < 0.01) and ammonium (P < 0.01), but had no correlation with the others.

We evaluated the solubility and bioaccessibility of Fe and Cu in Crassostrea rivulari and Paphia undulate by in vitro whole-bionic digestion model. The results show that: 1) At the stomach digestive stage, the solubilities of Fe and Cu in cooked C.rivulari and P.undulate were higher than those in raw ones, which was contrary to the case at intestinal digestion stage; 2) The bioaccessibility of Fe and Cu in cooked C.rivulari increased by 7.3% and 4.6%, respectively, and the bioaccessibility of Fe in cooked P.undulata increased by 11.5% while that of Cu decreased by 11.5%;3) Eating C.rivulari could provide coastal residents at most with 15.5% and 25.9% of the daily intake of Fe and Cu, respectively, while eating P.undulata could provide with over 6.4% and 3.1% of Fe and Cu, respectively. In general, eating C.rivulari provides human body with more daily intake of Fe than eating Paphia undulate, and even more when they are cooked.