泥东风螺Babylonia lutosa（Lamarck）的人工育苗技术

本文对泥东风螺工厂化人工育苗的主要技术环节进行了初步探讨。幼体培育密度为5万个／m^3，以金藻、扁藻、小球藻为饵料，并根据水质的好坏结合适当的换水量，能成功的获得变态稚贝，变态率达30％;稚贝培育密度为3000粒／m^2，以蟹肉，杂鱼肉为饵料，最终获得规格0．5～1cm的螺苗150万粒。整个育苗工艺达到工厂化生产要求。     

魁蚶常温育苗高产技术研究

6月上中旬采攮主荣成海域的魁蚶，在常温条件下，投喂小球藻和小新月菱形藻，经11天促熟便可自然产卵。幼虫培育主要用湛江等鞭金藻和小球藻混投，育成率达55．6％，340m^3水体出壳长700μm以上稚贝20．1亿粒（591．2万粒／m^3)，经40余天海上保苗出商品苗3．52亿粒（103．53万粒／m^3)，保苗率17．5％。     

菲律宾蛤仔苗种繁育技术研究

2005-2006年度,共利用800 kg亲贝进行了4批育苗,获得受精卵2.33×10^10粒,D形幼虫15734×10^10粒,平均孵化率68.8%。受精卵经22～25 d的培育,稚贝规格达210～296μm,2005、2006年度单位水体出苗量分别为1.315×10^6粒/m^3、2.797×10^6粒/m^3,出池稚贝的平均壳长分别为265μm、228μm。分别采用干露法和用常温阴干刺激加流水法进行催产,平均每千克亲贝所获得的受精卵、D形幼虫及孵化率前者分别是后者的33.5%、20.32%和60.6%。     

方斑东风螺室内人工育苗试验

为探索方斑东风螺的人工育苗技术,进行了室内人工育苗试验。采用降温干运法将亲螺从湛江水产学院运回试验基地,控制培育池水深25-30cm,海水比重1．017,水温28-30℃,保持充气和流水刺激,投喂新鲜的蟹肉和鱼肉。收集亲螺产出的卵囊,冲洗消毒后放入孵化池孵化。培育单细胞藻类作东风螺幼体的饵料,用蟹肉和鱼肉培育稚螺。试验共孵化出幼体550万粒,培育出5．5-17．5mm的稚螺40万粒,培育成活率为8％。     

密度及饵料对鲍苗生长与成活率的影响

研究了后期面盘幼虫不同采苗密度、不同底栖硅藻与稚鲍不同培育密度,对鲍苗的生长与成活率的影响。认为最佳采苗密度应为2万个／m2后期面盘幼虫;当地底栖硅藻混合种的饵料效果优于纯种,剥离后稚鲍的培育密度不直超过4000粒／m2。在640m2水面中有出壳长1．2～1．5cm鲍苗201．6万粒,平均出苗量3150粒／m2。专家鉴定认为,本课题在皱纹盘鲍不同育苗密度、不同饵料对育苗效果的研究方面居国内领先水平。     

方斑东风螺规模化苗种繁育技术研究

利用从自然海区诱捕的4307个方斑东风螺为亲螺,在体积分别为22 m3和45 m3的室内水泥池以及体积为18m3的室外水泥池(水体总体积为4218 m3)中共获得变态2～4 d的稚螺3785.4万粒,培育出变态稚螺8975粒/m3.收集刚变态稚螺于未铺设砂层的育苗池内暂养9～12 d,暂养后存活稚螺共计2281.8万粒.暂养平均成活率60.3%.暂养后稚螺再放养于铺有约3 cm细砂层的水泥池中进行苗种培育41～88 d,共培育出壳高0.6～1.8 cm的螺苗1318.3万粒,暂养后稚螺培育成螺苗成活率57.8%;从变态2～4 d稚螺培育成螺苗的成活率34.6%.     

日本真牡蛎室内人工育苗试验

为解决日本真牡蛎浅海吊养、滩涂播养、虾池混养大量用苗问题，1990年进行了日本真牡蛎室内人工育苗试验。探索到亲蛎肥育、采卵孵化、幼虫培育、附着变态、稚贝培养、下海过渡等重要技术，在118m^3水体中育出稚贝5196.1万粒，平均1m^3水体出稚贝44万粒，平均壳长7mm。1991年1月，国内著名专家鉴定认为，该成果居国内先进水平。     

栉孔扇贝中间育成技术的研究

我国的扇贝养殖业目前主要靠人工育苗获得苗种。在人工育苗中室内幼虫培育和稚贝附着方面技术上基本过关，每米^3出池稚贝(壳高300-400微米)高达228万粒。但是，稚贝出池下海到商品苗(壳高1厘米左右)的中间育成过程中，生产技术上存在很多问题，主要表现在育成率低(一般只有5％左右)，单位水体出苗量少，仅3-5万粒／米^3。     

菲律宾蛤仔苗种土池中问培育及越冬生产试验

利用26000m^2(39亩)和31349m^2(47亩)2个养虾池，分别移入在室内培育的菲律宾蛤仔壳顶后期幼虫和双水管稚贝各80亿粒和9．7亿粒，经土池中间培育、越冬后，共生产出2000—3000粒／500g幼贝7．9亿粒，成活率分别达到4．5％和4．3％。     

虾夷马粪海胆秋季育苗技术研究

秋季利用单细胞藻类培养池41个，育苗水体246m^3，培育出胆径1．1cm的幼胆300．6万个，单位水体出苗量12200个／m^3。全面探讨了种胆促熟、孵化以及幼体、稚胆、幼胆的培育技术。     

Association between the interannual variation in the oceanic environment and catch rates of bigeye tuna (Thunnus obesus) in the Atlantic Ocean

The environmental processes associated with variability in the catch rates of bigeye tuna in the Atlantic Ocean are largely unexplored. This study used generalized additive models (GAMs) fitted to Taiwanese longline fishery data from 1990 to 2009 and investigated the association between environmental variables and catch rates to identify the processes influencing bigeye tuna distribution in the Atlantic Ocean. The present findings reveal that the year (temporal factor), latitude and longitude (spatial factors), and major regular longline target species of albacore catches are significant for the standardization of bigeye tuna catch rates in the Atlantic Ocean. The standardized catch rates and distribution of bigeye tuna were found to be related to environmental and climatic variation. The model selection processes showed that the selected GAMs explained 70% of the cumulative deviance in the entire Atlantic Ocean. Regarding environmental factors, the depth of the 20 degree isotherm (D20) substantially contributed to the explained deviance; other important factors were sea surface temperature (SST) and sea surface height deviation (SSHD). The potential fishing grounds were observed with SSTs of 22–28°C, a D20 shallower than 150 m and negative SSHDs in the Atlantic Ocean. The higher predicted catch rates were increased in the positive northern tropical Atlantic and negative North Atlantic Oscillation events with a higher SST and shallow D20, suggesting that climatic oscillations affect the population abundance and distribution of bigeye tuna.     

Rare serotype occurrence and PFGE genotypic diversity of Streptococcus agalactiae isolated from tilapia in China

Previously, we reported 10 PEGE types of 85 tilapia Streptococcus agalactiae(GBS), which shifted from Streptococcus iniae in China, by using PEGE method. Presently, larger and more representative tilapia GBS were isolated, for the ?rst time in China, to characterize their serotypes and genetic diversities more precisely than had done before. 168 GBS strains were distributed in ?ve provinces of China, in which Guangdong, Guangxi and Hainan were the major ones, holding36.9%(62/168), 37.5%(63/168) and 19.6%(33/168), respectively. Serotypes, Ia, Ib and III, were observed in these strains and the most predominant one was Ia(95.2%), which mainly distributed in Guangdong, Guangxi and Hainan. Ia initially occurred in 2009, it shoot up to 32.1% in 2010,but decreased to 16.1% in 2011 before went up to 45.2% in 2012. Ib sporadically occurred during2007–2011, III onlyoccurred in 2012. 14 different PFGE types, including 4 new types(N, O,P and Q), were observed, in which B, D, F and G were the predominant types, holding 83.9%(141/168) of the total GBS strains. Ia corresponded to 11 PFGE types(A–H, N–P), in which type D predominated(51%). Ib represented 3 genotypes(I, J and Q) and III harbored only 2genotypes(N and F). Type N and Fsynchronously presented in Ia and III. In summary, the genetic diversity of tilapia GBS varied by serotypes and changed with geographical locations and years.Although Iastillpredominated, new rareserotypeIII alreadyoccurred in China.     

Evaluation of a Fast Method Based on the Presence of Two Restriction Sites in the Mitochondrial ND5 (mt ND5) Gene for the Identification of Scomber Species

The purpose of this work was to evaluate the suitability of a method based on the presence of two restriction sites (for Hae III and Hindf I) in the mitochondrial NADH dehydrogenase subunit 5 (mt ND5) gene to identify Scomber species. The evaluation was performed on 144 reference and market samples by sequencing of the entire 505-bp fragment of the mt ND5 gene and of a 464-bp fragment of the Kocher fragment of the cytochrome b gene (mt Cytb). Sequence analysis of any of the two fragments allows the identification of each of the four Scomber species, but S. japonicus and S. colias had the same restriction sites at the ND5 amplicon and would not have been differentiated by this analysis. Similarly, loss of the Hae III site in some S. scombrus individuals would have misidentified them as not being Scomber. All the market products were correctly labeled except one acquired in Spain labeled as originating in the Atlantic and containing S. japonicus.     

Growth performance,digestive enzyme activity and immune response of Japanese sea bass,Lateolabrax japonicus fed with fructooligosaccharide

In this experiment, a feeding trial was performed to determine the effects of fructooligosaccharide (FOS) on growth performance, digestive enzyme activity and immune response of Japanese sea bass, Lateolabrax japonicus juveniles (initial weight 38.3 ± 0.5 g), and the fish were examined following feeding with six levels of FOS (0, 0.5, 1, 2, 4 and 6 g/kg) for 28 days. Significant enhancement of weight gain (WG) and specific growth rate (SGR) was found in fish fed 1 g/kg FOS incorporated diets (p < .05), while the feed conversion ratio (FCR) in the 1, 2 g/kg FOS groups reduced significantly compared with the control (p < .05). Besides, the crude lipid in the 4, 6 g/kg FOS groups increased significantly compared with the control (p < .05). On the other hand, the erepsin and lipase activities significantly elevated in intestine of fish fed 2 g/kg FOS (p < .05) and the lysozyme activity in serum of fish fed 2 g/kg FOS were significantly higher than that in the control (p < .05). Moreover, the alkaline phosphatase activities in serum of fish fed 0.5, 1, 2 g/kg FOS were significantly higher than in control (p < .05). Regression analysis showed that the relationships between dietary FOS levels and either SGR, FCR, erepsin or lysozyme activities were best expressed by regression equations, and the optimal inclusion levels are 1.37, 1.80, 3.06, 3.11, 1.93 and 1.80 g/kg for SGR, FCR, erepsin, lipase, lysozyme and total superoxide dismutase activities, respectively. Overall, this study revealed that FOS incorporated diets could beneficial for L. japonicus culture in terms of increasing the growth, digestion and immune activities. Under the present experimental condition, the optimal supplementary level of FOS in the diet of L. japonicus is 1–3 g/kg.     

Growth hormone (GH) and reproduction: a review

Interaction between growth and reproduction occurs in many vertebrates and is particularly obvious at certain stages of the life cycle in fish. Endocrine interactions between the gonadotropic axis and the somatotropic axis are described, the potential role of GH being emphasised. A comparative analysis of these phenomena in mammals, amphibians and fish, suggests a specific role of GH in the physiology of puberty, gametogenesis and fertility. It also shows the original contribution made by studies on the fish model in this field of investigations.     

Purification and partial characterization of GtHs (cfLH and cfFSH) from Indian walking catfish (Clarias batrachus) (L.) and development of a homologous ELISA for cfLH

Two gonadotropins (GtH; Qa and Qb) were purified by gel filtration and ion exchange chromatography from the pituitaries of Indian walking catfish (Clarias batrachus). The presence of GtH during purification was assessed by in vitro oocyte maturation and in vivo steroidogenic activity, and their identities were determined by elution profiles, molecular weight, biological activities and yield. The molecular weights of Qa and Qb were 37 and 42 kDa, respectively, and composed of distinct subunits (Qa: 20 and 14 kDa and Qb: 26 and 18 kDa). Polyclonal antibodies raised against Qa immunostained Qa, Qb and pituitary GtH cells. A competitive Qa‐ELISA was developed whose sensitivity was 6.25 ng mL^?1 (1.25 ng well^?1) with intra‐ (3.5%) and inter‐ (12.4%) assay coefficients of variation. Displacement curves parallel to the standard were obtained with plasma and pituitary extracts of catfish, Qb and carp GtHII. The assay was validated by measuring the plasma Qa levels after LHRH treatment and in relation to ovarian growth in the female catfish during different reproductive phases. Based on the results, Qa and Qb corresponded to fish LH and FSH respectively. The findings will increase the knowledge of the mechanisms controlling fish reproduction and identification of sensitive phases in fish in captivity for hormonal manipulation.     

Controlled infection of Poecilia reticulata Peters (guppy) with Tetrahymena by immersion and intraperitoneal injection

Tetrahymena is a protozoan parasite, which infects guppy, Poecilia reticulata Peters, and causes substantial economical losses in commercial farms worldwide. Studies of guppy infected by Tetrahymena require standardized infection protocols. The LD50 for Tetrahymena infection of guppies by intraperitoneal (IP) injection was calibrated, and the level obtained was 946 parasites per fish. Guppy infection with Tetrahymena by immersion, imitating the natural route of infection via the integument, was studied under normal or stress conditions. Exposure to cold and netting (CNI) and to cold only (CI) followed by immersion exposure to 10 000 Tetrahymena per mL resulted in 22.5% and 19.2% mortality, respectively, as compared to 14.2% and 10% in groups that were netted only (NI) or non‐stressed (I). Histopathology revealed that immersion infection resulted in a systemic infection. Lysozyme levels, measured 3 weeks after infection, were significantly higher in the CNI group (288 μg per mg protein) compared with CI‐, NI‐ and I‐treated groups (94.5, 64 and 62.3 μg mg^?1, respectively). There was no evident parasite immobilization activity in body homogenates, suggesting no development of acquired immunity. Re‐infection by IP injection revealed no increase in protection in any of the treatment groups, mortality range of 56.3–75%, higher than in the non‐exposed control (40.6% mortality).