牡蛎养殖

牡蛎是世界大宗的海产贝类。据联合国粮农组织(FAO)统计,1994年世界牡蛎产量为123．9万吨,占当年世界海产贝类总产量的12．5％。     

太平洋牡蛎垂下式养殖方法与技术

太平洋牡蛎Crassostrea gigas(Than beng)是广盐性、广温的内湾贝类,具有个体大、生长快、产量高、适应性强的特点。它的软体部丰满细嫩,味道鲜美,营养价值高,是人们喜食的海产佳肴,素有“海中牛奶”之称,已被世界沿岸国家所普遍养殖。太平洋牡蛎将成为贝类养殖业的一大支柱,我国海岸曲折、内湾多,浅海面积广宽,潮流畅通,生物饵料丰富,适合于开发太平洋牡蛎养殖。笔者在承担完成农业部下达的牡蛎大面积高产养殖技术《万亩丰收计划》项目的同时,围绕着如何提高单产、降低成本、增产增收进行试范,结果经济效益明显,本文就太平     

葡萄牙牡蛎“金蛎1号”

<正>牡蛎其肉质鲜美,营养价值较高,素有"海中牛奶"之美称。2014年世界牡蛎产量达516万吨,产值41.7亿美元;中国牡蛎产量居全球首位,达435万吨,占世界牡蛎产量的84.3%,特别是近十五年来中国牡蛎年产量均在300万吨以上,牡蛎已成为中国乃至世界养殖产量最大的经济贝类。自2009年起,福建省水产研究所收集福建沿海诏安、漳浦、罗源及广东南澳等牡蛎主养区野生和养殖的葡萄牙牡蛎人工繁育后代构建基础群     

牡蛎的品质及其开发利用

牡蛎是沿海习见且大量生长的一种贝类，属于软体动物门、瓣鳃纲、牡蛎科。我国沿海盛产的牡蛎，主要有近江牡蛎、长牡蛎、褶牡蛎、花缘牡蛎、大连湾牡蛎、密鳞牡蛎等。牡蛎是广东沿海养殖的主要贝类之一，碍石湾、红海湾、深圳湾、唐家湾、镇海湾和海陵湾等地有大量养殖。     

我国贝类HACCP体系有效实施途径的探讨

我国生活着800余种海洋贝类,贝类产量名列世界第一。海水贝类养殖产量占海水养殖总产量的80%,是海水养殖业的一个重要组成部分。养殖品种有牡蛎、贻贝、扇贝、文蛤、青蛤、蛏、蚶、鲍等十多种,是我国水产品出口创汇的重要品种。双壳贝类,例如牡蛎、杂色蛤、毛蚶、文蛤,具有非选     

乳山湾水体重金属含量的季节变化与养殖贝类对水体重金属的生物富集效应

为了解乳山湾近岸海域重金属污染情况及养殖贝类对重金属富集情况,按春、夏、秋、冬四个航次采集湾内和湾外的表层海水,并于秋季采集湾内养殖的太平洋牡蛎(Crassostrea gigas)分析海水及牡蛎体内Cu、Pb、Zn、Cr、Cd、As、Hg等7种重金属含量,评价海水质量与养殖贝类的食用安全。结果表明:乳山湾湾内湾外海域水质较好,除冬季Zn以及春、秋两季的Hg符合二类海水水质标准,其余点位均符合一类海水水质标准,海水水质为"清洁"。乳山湾湾内和湾外沉积物中各重金属的含量均低于第一类海洋沉积物标准,没有受到明显的污染。乳山湾内养殖牡蛎体内Cd和Zn的浓度远远高于湾内水体中重金属的浓度,表明太平洋牡蛎对重金属具有较强的富集作用,但仍符合二类海洋生物质量标准。     

乐清县大抓滩涂贝类苗种增殖

浙江乐清湾是一个半封闭型的内湾,风浪小,潮流缓,沿湾有淡水注入、营养盐丰富,涂质肥沃、水温、盐度适中,是滩涂贝类繁殖生长的优良场所。乐清县地处湾西侧,浅海广,滩涂阔,有悠久的缢蛏、泥蚶、牡蛎三大贝类养殖历史,过去由于     

长牡蛎“海蛎1号”

正一、品种概况(一)培育背景牡蛎是一种重要的海洋水产资源,是传统的海洋食物,也是世界上重要的海水养殖贝类之一。2018年我国牡蛎养殖面积约1.44×10~5ha,产量约5.14×10~6t(中国渔业统计年鉴,2019)。我国牡蛎产量连续多年稳居世界首位,占同期世界产量的81%,但每年还要从欧洲、美洲和澳洲进口一定数量的牡蛎,以满足国内高端市场的需求。     

太平洋牡蛎(Crassostrea gigas)筏式养殖技术

太平洋牡蛎即日本真牡蛎。是广盐、广温性的内湾品种,具有个体大、生长快、产量高、适应性强的特点,是世界养殖牡蛎的优良品种之一。大连市於1982年从日本引进太平洋牡蛎苗种。     

琼粤桂贝类养殖遭殃

<正>"威马逊"在海南海口、文昌和琼海三市登陆,接着横扫广东雷州半岛,之后又从广西钦州湾西岸的防城港市光坡镇登陆,正面袭击钦州港口、茅尾海及大风江牡蛎主养区,给海南、广东和广西三省区的贝类养殖造成了巨大的损失。严重损失贝类养殖损失最严重的是广西省。牡蛎养殖业是广西特色渔业的支柱产业,其主产区主要分布在茅尾海(防城港、钦州)及钦州港口、大风江(钦州、合浦)和廉州湾(合浦、北海)。据统计,2013年广西牡蛎养殖面积1.9万公顷,年产量47.3万吨,产     

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 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).     

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.     

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.     

Effect of iodophor disinfection of non‐hardened Salmo trutta eggs on their bacterial and fungus load

This study investigated the efficiency of iodophor disinfection (135 ppm active iodine for 15–30 min) of non‐hardened Salmo trutta eggs against different groups of bacteria and against fungus. Egg samples were taken from non‐disinfected and from disinfected eggs, microorganisms were cultured on specific nutrient media and their mass was measured by turbidimetric methods. Bacteria and fungus mass of non‐hardened eggs could be reduced but not eliminated by iodophor disinfection with 135 ppm active iodine for 15 min. The extent of reduction was 47–65% (Experiment 1). The efficiency of disinfection increased with disinfection time as the reduction in bacteria and fungus mass was 40–55% after 15 min and 58–74% after 30 min (Experiment 2). Disinfection efficiency of iodophor solution diluted in water (reduction 49–57%) and of iodophor solution diluted in sodium chloride solution iso‐osmolar to the oocytes (reduction 52–61%) was similar (Experiment 3). The reduction in bacteria and fungus mass was persistent as it was 39–72% lower in embryos deriving from disinfected eggs than in embryos deriving from non‐disinfected ones (Experiment 4). In conclusion, the tested disinfection method is inadequate to eliminate pathogens completely but it could positively influence immune defence of eggs and embryos.     

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.