苏鲁沿海地区日本对虾亲虾及受精卵孵化培育技术探讨

随着日本对虾在苏鲁2省沿海地区养殖的迅速发展,使得日本对虾虾苗的需求不断增加,不少当地育苗企业开展了日本对虾虾苗的生产。由于本地海区没有日本对虾亲虾,育苗所用亲虾主要来源于台湾海峡海区,即福建沿海和台湾地区,以台湾地区为主要出产地。对于育苗企业来说如何搞好日本对虾亲虾及无节幼体的培育非常关键,它不仅影响到企业的效益,也影响到日本对虾虾苗的生产和日本对虾的养殖。     

应用重量法计量出池日本对虾虾苗的研究

对日本对虾仔虾在室内人工养殖条件下的商品体长(xcm)与单位重量(500克)含有的尾数(y万尾)进行了测定,得出回归方程y=5.829x~(-2.5828)。将0.6～1.29cm的虾苗在单位重量时的虾苗数列成表格,供出售与购买虾苗者参考。对应用重量法出池日本对虾虾苗应注意的问题进行了讨论。     

斑节对虾苗对不同比重海水适应性的研究

在我国南方沿海的对虾养殖中，往往于放苗阶段遇到大雨而使养殖池水的比重发生急剧变化，从而影响虾苗放养后的存活率。因此，了解斑节对虾苗对海水比重突变的适应能力，在养殖生产上是十分必要的。为此，我们进行了不同大小斑节对虾苗对不同海水比重变化的适应性的研究，旨在为养殖生产提供参考依据。现将结果报告如下。     

日本对虾育苗技术

<正> 我们于1979年4月访问了日本对虾养殖中心山口县,在该县秋穗、旭商事养虾场和濑户内海栽培渔业中心考察、学习。日本对虾 Penaeus japonicus养殖的发展乃是狠抓苗种关、科研成果促进生产发展。因此,在介绍育苗技术之前介绍其发展简史,研究日本人在发展虾苗生产所走过的路,扬长避短,可为发展我国对虾养殖业提供借鉴。一,育苗技术的发展简史日本对虾育苗技术发展史大体可分四个阶段。(一)基础研究时期(1933～1958),1933年日本     

日本对虾亲虾培育及受精卵孵化技术

随着日本对虾在苏鲁两省沿海地区养殖的迅速发展，对日本对虾虾苗的需求不断增加，不少当地育苗企业开展了日本对虾虾苗的生产。由于本地海区没有日本对虾亲虾，育苗所用亲虾主要来源为台湾海峡海区，即我国福建沿海和台湾地区，以台湾地区为主要出产地。近几年来亲虾的产量逐年下降，福建沿海已很少有亲虾供应，亲虾基本来源于台湾地区，因需求趋于旺盛，亲虾价格不断攀升；因此对于育苗企业来说如何搞好日本对虾亲虾培育及受精卵的孵化非常关键，     

中国对虾种苗长途运输技术探讨

关于虾类的保活运输技术的研究,以往有张述技(1981)进行日本对虾保活运输加工工艺的研究;张启同(1990)对日本对虾保活运输进行试验;林瑞才等(1992)进行瓦楞纸箱活体运输日本对虾的探讨;今村氏(1974)曾报道从台湾运输日本对虾种虾到日本;Tabb等(1972)曾对红对虾种虾运输进行研究;国内许多水产界学者对中国对虾的种虾和虾苗运输进行了研究。本文对中国对虾(Penaeus Qrientalis)的种虾和虾苗长途运输进行了技术探讨,为中国对虾北种南移,发展多品种对虾养殖事业提供资料。     

日本对虾养殖试验

日本对虾耐低温,可在秋季放苗,冬、春季收获,适宜我国南方沿海在冬季进行第二或第三造养殖,是对虾养殖的新品种,且日本对虾具有活力强,耐干露等特点,适于鲜活销售,故有利于提高养虾的经济效益。因而试验和推广日本对虾的养殖,对我国对虾业的进一步发展,无疑具有重大意义。日本对虾俗称花虾、青尾虾、竹节虾,是南海北部重要的经济虾类。为了探索日本对虾在汕尾地区养殖的可行性,我们于1990年10月在汕尾市城区江草镇养虾场的781亩虾池,投放人工培育的日本对虾苗,进行养殖试验,取得较好的效果。现将试验情况叙述如下:     

日本对虾防病高产养殖技术研究

日本对虾近年来受白斑病毒病(WSSV)等危害非常严重,养殖成功率低。现国内日本对虾养殖主要与贝类、梭子蟹、鱼类等混养,大都为粗放粗养方式。为探索日本对虾精养高产技术,舟山市水产养殖病害防治院病害监测点长白养殖场在南美白对虾养殖连续多年获得高产的基础上,于2005年开展了日本对虾防病高产技术研究。通过改变旧有养殖模式,采取一系列综合防病措施,使日本对虾养殖平均单茬亩产达到316千克,亩产最高塘达到367千克的产量,取得了较好的经济效益。下面将试验研究情况总结如下:一、试验结果试验池8只,每只300米2,2005年5月30日放养虾苗,苗…     

外刊报道:中国产日本对虾苗种在日本全部死亡

由于台湾省养殖日本对虾发生病毒原因,可是日本于今年转向从中国进口日本对虾虾苗。可是,中国产的日本对虾在日养殖期间因患病而全部死亡,至今死病原因尚未查清。作为主要产地的日本天草,原计划夏季上市200t 左右,其中中国产的100t。但因发病已死亡70～     

罗氏沼虾虾苗对环境因子的适应性研究

为研究罗氏沼虾虾苗对水温、溶氧量、pH、盐度等环境因子的适应性,采用自行设计的试验装置,在人工控制的水体环境条件下,进行了虾苗对水温、溶氧量、pH及盐度的单因子适应性试验。通过对试验数据的分析,得出罗氏沼虾虾苗的适宜生长温度为23~28 ℃,最适生长温度为24~25 ℃,最适pH为7.8~8.9,溶氧量在7.8~8.9 mg/L,最适盐度为12~13。     

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.     

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).     

Protein and amino acid composition from the mantle of juvenile O ctopus vulgaris exposed to prolonged starvation

Protein and amino acid composition of the mantle of juvenile O ctopus vulgaris (Cuvier, 1797) during fasting for 27 days were determined. Average protein content of octopus mantle was of 711.19 ± 46.80 g kg^?1 DW, and it decreased with increasing fasting days. The non‐essential amino acids content was higher (486.18 ± 11.08 g kg^?1 protein) than essential amino acids (425.82 ± 9.15 g kg^?1 protein) at the start of the experiment (unstarved animals). The results suggest that the amino acid profile of the mantle where the most abundant amino acids are Arg, His, Lys, Gly, Leu and Pro could indicate a prolonged fasting condition (>20 days) or poor nutrition of O . vulgaris. This study supports the idea of using mantle for metabolic needs of starved O . vulgaris suggesting that the degradation pathway of amino acids to pyruvate and tricarboxylic acid cycle intermediates was favoured contrary to the degradation pathway of ketogenic amino acids. Special considerations should be taken concerning Thr, Ile, Ser, Ala, Asx (Asp, Asn), Glx (Glu, Gln) (because of their fast intake) and Lys and His (due to their stable contents) during a prolonged period of fasting.     

Nitrogenous waste excretion and accumulation of urea and ammonia inChalcalburnus tarichi (Cyprinidae), endemic to the extremely alkaline Lake Van (Eastern Turkey)

The endemic, anadromous cyprinidChalcalburnus tarichi is the only fish species known to occur in alkaline Lake Van (Eastern Anatolia, Turkey). EightC. tarichi were maintained individually in Lake Van water (17 – 19°C; pH 9.8; 153 mEq·I^–1 total alkalinity; 22 total salinity) and tank water samples analyzed for 24 h in 2 to 4 h intervals. At zero time, < 1µM ammonia was present and urea was undetectable in the tank water; at 24 h, total ammonia and urea made up 114±32 and 35±25µM, respectively. Over the experimental period, ammonia-N and urea-N excretion averaged 1041±494 and 607±169moles·kg^–1 fish·h^–1, respectively. The extent of urea excretion was highly variable between specimens. Uric acid excretion was not detectable.Urea was present at high concentrations in all tissues and plasma (25 – 35moles·g^–1·ml^–1) of freshly caughtC. tarichi; total ammonia content of the tissues was by a factor of 1.9 (liver) to 3.0 (brain) lower. High arginase activity (2.4±0.2 U·min^–1·g^–1) was detected in the liver ofC. tarichi but ornithine carbamoylphosphate transferase, a key enzyme of the ornithine-urea-cycle, was absent. Ureagenesis is likely through degradation of arginine and/or uricolysis. High glutamine synthetase activity (11±0.6 U·min^–1·g^–1) and low ammonia content in brain suggest that, like other teleosts,C. tarichi has an efficient ammonia detoxification in the brain, but in no other tissue.Nitrogenous waste excretion at alkaline pH is discussed. The ability ofC. tarichi to excrete high levels of ammonia at extremely alkaline pH is unique among teleosts studied so far. The mechanism of ammonia excretion under Lake Van conditions remains to be elucidated.     

Imported ornamental fish are colonized with antibiotic‐resistant bacteria

There has been growing concern about the overuse of antibiotics in the ornamental fish industry and its possible effect on the increasing drug resistance in both commensal and pathogenic organisms in these fish. The aim of this study was to carry out an assessment of the diversity of bacteria, including pathogens, in ornamental fish species imported into North America and to assess their antibiotic resistance. Kidney samples were collected from 32 freshwater ornamental fish of various species, which arrived to an importing facility in Portland, Oregon from Colombia, Singapore and Florida. Sixty‐four unique bacterial colonies were isolated and identified by PCR using bacterial 16S primers and DNA sequencing. Multiple isolates were identified as bacteria with potential to cause disease in both fish and humans. The antibiotic resistance profile of each isolate was performed for nine different antibiotics. Among them, cefotaxime (16% resistance among isolates) was the antibiotic associated with more activity, while the least active was tetracycline (77% resistant). Knowing information about the diversity of bacteria in imported ornamental fish, as well as the resistance profiles for the bacteria will be useful in more effectively treating clinical infected fish, and also potential zoonoses in the future.