细鳞鱼亚种问题的研究

本文对鸭绿江、河北省和甘肃省渭河上游的细鳞鱼作了解剖观察,对分布在我国各地的细鳞鱼的分类特征作了比较观察,并用生化分类方法对上述三地区细鳞鱼作进一步分析。结果认为细鳞鱼属在我国只有细鳞鱼Brachymystax lenok(Pallas)一种,无亚种的分化。     

小滦河流域细鳞鱼增殖保护现状与对策

1 细鳞鱼增殖保护现状 细鳞鱼,学名秦岭细鳞鲑,是国家二级重点保护水生野生动物.为做好细鳞鱼的保护工作,1995年承德市组织水产技术人员开始着手细鳞鱼驯化养殖技术研究.从1997年省市开始研发,2002年细鳞鱼人工繁育技术获得承德市科技进步一等奖.同年,在农业部和河北省水产局的大力支持下,在围场机械化林场建设了细鳞鱼繁育场,养殖细鳞鱼亲鱼500余尾,年可孵化培育5万多尾细鳞鱼苗种.此后,每年承德市和围场县渔政部门都要联合开展细鳞鱼人工增殖放流,特别是2006年,国家、省、市、县四级渔政部门一次性在坝上小滦河流域放流细鳞鱼苗种5万尾,开创了全国之最.     

小滦河细鳞鱼自然生存环境及人工驯养技术

细鳞鱼（Brachymystax Lenokpallas）,隶属于鲑形目（Salmoniformes）鲑科（Salmonicdeir）细鳞鱼属,又称细鳞鲑,秦岭细鳞鲑,是国家二级重点保护水生野生动物。分布于河北省北部小滦河上游的细鳞鱼是我国现存细鳞鱼资源的重要组成部分。为做好细鳞鱼保护工作,省市县业务部门给予了大力支持和帮助,划定了细鳞鱼自然保护区,并于2002年在塞罕坝机械林场建立细鳞鱼繁育场一处,重点开展人工繁殖细鳞鱼的工作,几年来已累计向小滦河放流人工繁殖细鳞鱼苗15万尾,对细鳞鱼的增殖保护起到了一定作用。     

细鳞鱼人工繁殖研究进展

正细鳞鱼是国家二级保护水生野生动物,在鱼类学和动物地理学上具有重要的学术研究价值。细鳞鱼生长快,肉质细嫩,无肌间刺,味道鲜美,有防止血栓、加快伤口愈合之功能,具有很高的营养价值。一、细鳞鱼生物学特征细鳞鱼(Brachymystax lenok Pallas),又称细鳞鲑,秦岭细鳞鲑、鲑形目、鲑科、细鳞鱼属,     

细鳞幼鱼小瓜虫病的防治

细鳞鱼(Brachymystax lenok Pallas)又名细鳞鲑,属于鲑形目、鲑科、细鳞鱼属,地方名江细鳞鱼,主要栖居于中国东北地区、俄罗斯远东地区和韩国的主要河流。     

野生细鳞鱼池塘驯养及人工繁殖技术研究

细鳞鱼 ,又称细鳞鲑、秦岭细鳞鲑(Ｂｒａｃｈｙｍｙｓｔａｘｌｅｎｏｋ) ,为鲑形目Ｓａｌｍｏｎｉ ｆｏｒｍｅｓ、鲑科Ｓａｌｍｏｎｉｄａｅ、细鳞鱼属。中国仅1属 1种 ,是一种名贵的鲑科陆封型冷水鱼。为保护这一珍稀物种 ,我国野生动物保护法已将其列入国家二级重点保护水生野生动物。细鳞鱼主要分布在我国的图门江、鸭绿江、松花江 ,向西经辽河、滦河、秦岭直至额尔齐斯河。近几年来 ,细鳞鱼资源急剧衰退 ,已濒临灭绝。因而 ,研究细鳞鱼的人工驯养、繁殖 ,继而开展细鳞鱼的人工养殖和增殖 ,拯救这一珍贵物种 ,具有十分重要的意义。课题组…     

人工养殖细鳞鱼常见疾病及其防治

细鳞鱼（Brachymystax lenok）属鲑形目（Salmoniformes）、鲑科（Salmonidac）、细鳞鱼属（Brachymystax）（易危,国家二级保护动物）,地方名为江细鳞鱼,主要栖居于中国东北地区、俄罗斯远东地区和韩国的主要河流。     

细鳞鱼的保护开发价值及繁养技术

主要介绍了细鳞鱼的分布及保护现状,分析了其市场价值与开发前景,并把现有的细鳞鱼繁殖、养殖技术进行简要说明,目的是为了有识之士共同探讨,共同保护和开发细鳞鱼这一前景广阔的冷水鱼品种。     

细鳞鱼仔稚鱼培育技术研究

<正> 细鳞鱼(Brachymystax lenok pallas),隶属于鲑形目(Salmoniformes)、鲑科(Salmonicdei)、细鳞鱼属,目前已濒临灭绝。为拯救这一濒临灭绝的珍贵物种,我们对野生细鳞鱼的池塘驯养及人工繁殖技术进行了研究,于2000年已获突破,并通过专家鉴定。为进一步摸索出细鳞鱼一整套人工养殖、繁育及苗种培育技术,达到人工养殖增殖目的,从2001年至2002年在围场,初步建设了细鳞鱼自然救护中心及人工繁育场,重点对细鳞鱼的仔稚鱼培育技术进行了试验研究。     

细鳞鱼网箱养殖技术试验

<正>通过在流水中设置网箱进行细鳞鱼养殖,同时在水泥池中设置对照组,在水源相同,饲料相同,管理方法相同的情况下,探讨鱼苗生长速度及病害发生情况,为细鳞鱼大面积网箱养殖提供基础数据。结果表明:在同等条件下,网箱养殖细鳞鱼生长速度比水泥池快65%。在水质、环境条件许可情况下,细鳞鱼可在网箱中进行大规模培育,水流量大小是影响细鳞鱼生长速度的主要因素。     

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.