乌苏里拟Chang人工繁育技术及开发利用——乌苏里拟Chang繁殖生物学及人工催产初步研究

对乌苏里拟鲿的繁殖生物学性状做了测定分析,在6月初时体长225-468mm的个体绝对怀卵数2684±1029粒,发现比自然繁殖期中的怀卵数量少,认为可能一些卵细胞增殖或发育尚未达到一定程度而影响怀卵数量.该鱼的卵子为橘黄色,卵径平均2mm,在水温15-17℃时,受精卵需要约96小时以上的胚胎发育,鱼苗出膜.人工繁殖分三个试验组HCG、LHRH-A+HCG和对照组,第一次注射均采用了DOS催熟,分别获得40%、85%、0的结果.     

乌苏里拟鲿人工繁育技术研究

在6月初时体长225-468 mm的个体,绝对怀卵数2684±1029粒,卵子为橘黄色,卵径平均2 mm,在水温15～17℃时,受精卵需要约96 h以上的胚胎发育出膜。人工催产试验以LHRH-A、HCG和DOS等不同种类和剂量试验,结果混合组获得产卵率85%,受精率75%的效果。苗种培育每亩投放鱼苗3万尾,经3个月培育结果表明,体长由1.21 cm增长至15.31 cm,体重由0.023 g/尾增重至28.25g/尾,成活率达96.8%。对肌肉营养组成进行分析,结果肌肉中粗蛋白含量为67.11%～82.11%；粗脂肪含量为8.90%～23.74%；灰分含量为4.95%～6.24%。     

钱塘江细体拟鲿人工繁育技术研究

选择从钱塘江捕捞的成鱼和人工养殖的成鱼作亲鱼,进行了细体拟鳞的人工繁殖和苗种培育试验.亲鱼在池塘内强化培育至性成熟,在繁殖季节,注射HCG+LHRH-A2+DOM催产激素,采用干法人工授精、网板附卵孵化,结果共获受精卵78.8万粒,平均受精率78.6%;孵出鱼苗47.9万尾,平均孵化率60.8%.经培育,获体长3.0～4.0 cm的夏花鱼种24.7万尾,平均成活率58.8%.     

乌苏里拟鲿人工繁育技术初探

为研究乌苏里拟鲿的人工繁殖和苗种培育技术,2011年5月和6月从吉林省鸭绿江地区采购两批亲鱼运回安徽进行了繁育试验。注射人工催产激素促熟催产,人工授精,水泥池流水孵化,土池施肥培水并用粉料培育鱼苗。试验结果:第一批次催产雌鱼260尾、雄鱼56尾,水温22.0～22.5℃,产卵率为35%,平均受精率55%;孵化水温19.5～23.0℃,因感染水霉,仅获得300多尾鱼苗。第二批次催产雌鱼275尾、雄鱼60尾,水温24.0～25.5℃,产卵率50%,平均受精率65%;孵化水温24.5～28.3℃,由于孵化期间使用亚甲基蓝防治水霉,孵化率达到75%。两个批次共繁殖鱼苗19万尾,培育出全长4.5～5.5cm的鱼种6万尾,培育成活率31.58%。     

乌苏里拟鲿人工繁育技术

<正>乌苏里拟鲿属鲇形目,鲿科,习底栖性,生活于缓流中。在南北方地区都可以养殖,此鱼耐温0～36℃左右,南方生长周期长,生长速度较快。其肉味鲜美无比,无肌间刺,食性广,病害少,市场需求旺盛,价格较优,前景十分看好,倍受广大消费者和养殖     

乌苏里拟鲿驯化养殖试验

<正>乌苏里拟鲿,俗名牛尾巴,为鲇形目、鲿科、拟鲿属鱼类。笔者于2006年开始对野生乌苏里拟鲿进行驯养、繁殖试验,初步掌握了该品种繁殖、养殖技术。试验表明,乌苏里拟鲿适应性较强,具有个体大、生长     

乌苏里拟鲿的人工繁育技术

乌苏里拟鲿（Pseudobagras ussuriensis）隶属鲶形目、鲿科、拟鲿属,又名乌苏里鮠,地方名牛尾巴,主要分布于我国黑龙江水系（黑龙江、乌苏里江、松花江、嫩江等水域）,20世纪90年代以前乌苏里拟鲿的自然产量仅次于同科黄颡鱼（Pelteobagrus fulvidraco）,位居第二位。鳞科鱼类绝大部分为小型鱼类,尼克里斯基于1985年研究证实乌苏里拟鳞是鳞科生长速度最快的种类,其最大个体体长可达1．0米。     

乌苏里鮠的人工繁育技术研究

2011年6月中旬进行了乌苏里鮠人工繁殖技术的研究,研究表明:体长159～191mm的亲鱼个体绝对怀卵量为1 314～4 374粒;体长221～258mm的亲鱼个体绝对怀卵量为3 753～6 840粒。卵子橘黄色,卵径平均2mm,水温25～26℃,受精卵经过49h26min的胚胎发育可破膜。催产药物为促黄体生成素释放激素类似物(LRH-A2)、马来酸地欧酮(DOM)和绒毛膜促性腺激素(HCG)的合剂,雌雄比例为20～30:1。     

乌苏里江大麻哈鱼人工催产技术初步研究

选取60尾雌性大麻哈亲鱼,分成S-GnRH-A组、HCG组和17α-20βp组,在2～4℃水温下分别进行不同催产药物的人工催产繁殖试验。结果表明,三组的催产率分别为10%、15%、65%,共有18尾亲鱼产卵,卵径0.54～0.66cm,平均怀卵量为3530粒,获得成熟卵63500余粒,受精卵51680粒,发眼卵38815粒。在6～9℃水温条件下,经59天孵化出苗,孵化鱼苗36370尾。     

乌苏里拟鲿苗种培育技术

选用经人工繁殖刚开口摄食的乌苏里拟鲿水花，在池塘和水族箱内同时进行培育。池塘每667m^2投放水花3万尾，水族箱内投放水花400尾。3个月培育结果表明，池塘养殖的乌苏里拟鲿体长由1．21cm增长至15．31cm，体重由0.023g／尾增重至28．25g／尾，成活率为96．8％；水族箱培育的乌苏里拟鲿体长增长至5．76cm，体重增长至1.92g／尾，成活率为33％。雌雄个体生长不均，池塘培育雌性个体平均体长为10．2cm，体重为16．5g／尾，雄性个体平均体长为21,8cm，体重为60Ag／尾；水族箱培育雌性个体平均体长为5．6cm，体重为1．49g／尾，雄性个体平均体长为6．6cm，体重为2．42g／尾。     

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.     

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).     

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.     

Influence of the antibacterial herbs, Solanum trilobatum, Andrographis paniculata and Psoralea corylifolia on the survival, growth and bacterial load of Penaeus monodon post larvae

The indiscriminate use of antibiotics and chemicals in shrimp hatcheries has led to biomagnification and that in turn could lead to rejection of a whole consignment. The application of the bioencapsulation technique as a tool for curative treatment in shrimp larvae was investigated. Herbs having antibacterial properties such as Solanum trilobatum, Andrographis paniculata and Psoralea corylifolia (methanolic extracts) were bioencapsulated in Artemia and fed to Penaeus monodon post larvae PL 1–25. The post larvae were reared in a medium inoculated with pathogenic bacteria such as Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella typhi and Vibrio sp. Post larvae reared in the non-inoculated water and fed with non-enriched Artemia exhibited 90% survival, highest specific growth rate (12.43%) and reduced bacterial load. P. monodon reared in the bacterial inoculated water and fed with the non-enriched Artemia exhibited the lowest survival (10–30%), specific growth rate (8.42–9.1%) and increased bacterial load (2.86 × 10³ to 3.76 × 10⁵ cfu/g). The methanolic extracts of the herbs helped to increase survival and specific growth rate and reduced bacterial load in the P. monodon culture system. Among the three herbal extracts, P. corylifolia enriched Artemia fed post larvae showed the tendency to higher survival (>50%), growth rate (11.5 averaged) and low bacterial load (1.12 × 10⁵ cfu/g). This revised version was published online in August 2006 with corrections to the Cover Date.     

Effects of cortisol on hepatic carbohydrate metabolism and responsiveness to hormones in the sea raven,Hemitripterus americanus

The sea raven, Hemitripterus americanus, is a sit-and-wait, low metabolic rate, marine teleost. The objective of this study was to determine i) whether cortisol implantation (50 mg. kg^-1) for 7 days altered hepatocyte metabolism, and hepatocyte responsiveness to epinephrine, glucagon and insulin, and ii) whether 8 weeks of food-deprivation modified the above response. Cortisol implantation significantly increased hepatocyte total glucose production and oxidation from alanine compared to the sham group. There was no cortisol effect on glycogen breakdown, suggesting that the activation of other pathways, including gluconeogenesis, are required to account for the increased glucose production. Epinephrine-mediated (10^-5M) glycogen breakdown and insulin-mediated (10^-8M) total glucose production were enhanced in hepatocytes of cortisol implanted sea ravens, but there were no change in any glucagon (10^-7M) effects. The enhanced glycogen breakdown in the absence of similar increases in total glucose production with epinephrine indicates mobilization of carbohydrate reserves for endogenous use by the liver. Food-deprivation for 8 weeks significantly decreased condition factor, plasma cortisol concentration and liver glycogen content in the sea raven, but had no effect on plasma glucose concentration. Hepatocyte total glucose production and flux rates from alanine increased significantly with food-deprivation. Moreover, food-deprivation increased responsiveness of total hepatocyte glucose production to the actions of glucagon and insulin, but not to epinephrine; none of these effects were modified by cortisol implantation. Our results indicate that cortisol in the sea raven exerts both a direct and an indirect or permissive effect on hepatocyte metabolism by modifying hepatocyte responsiveness to epinephrine and insulin stimulation. Cortisol implantation did not modify the effects of glucagon or food-deprivation in this species.     

Simulation and quantification of enrichment and retention processes in the southern Benguela upwelling ecosystem

Important environmental processes for the survival and recruitment of early life stages of pelagic fishes have been synthesized through Bakun's fundamental triad as enrichment, concentration and retention processes (A. Bakun, 1996, Patterns in the Ocean. Ocean Processes and Marine Population Dynamics. San Diego, CA, USA: University of California Sea Grant). This conceptual framework states that from favourable spawning habitats, eggs and larvae would be transported to and/or retained in places where food originating from enrichment areas would be concentrated. We propose a method for quantifying two of the triad processes, enrichment and retention, based on the Lagrangian tracking of particles transported within water velocity fields generated by a three‐dimensional hydrodynamic model. We apply this method to the southern Benguela upwelling ecosystem, constructing putative maps of enrichment and retention. We comment on these maps regarding main features of the circulation in the region, and investigate seasonal variability of the processes. We finally discuss the results in relation to available knowledge on the reproductive strategies of two pelagic clupeoid species abundant in the southern Benguela, anchovy (Engraulis encrasicolus) and sardine (Sardinops sagax). Our approach is intended to be sufficiently generic so as to allow its application to other upwelling systems.     

Effects of capture,loading density and transport stress on the mortality,physiological responses,bacterial density and growth of rohu <Emphasis Type="Italic">Labeo</Emphasis><Emphasis Type="Italic"> rohita</Emphasis> fingerlings

This study evaluated the effects of three levels of loading density (200, 300 and 400 g L⁻¹) and four levels of duration (1, 3, 6 and 9 h) on the mortality, plasma cortisol and chloride levels and growth of rohu Labeo rohita fingerlings in a transport simulation. While total immediate mortality was low (4–12%), delayed mortality was high (27–49%). Initial capture and handling were found to constitute the most stressful phase as indicated by elevated plasma cortisol. The levels of cortisol continued to rise at 6 and 9 h after transport, with the highest level observed at 9 h after transport. The level of plasma chloride fell after transport across all density levels and treatment durations. Specific growth rate (SGR, %/day) and total bacterial density (cfu/g) were not different between and within treatments, and between treatments and the controls. This study demonstrates that transport has a profound effect on the stress responses of rohu fingerlings. Although the level of immediate mortality was low, the higher level of delayed mortality has serious implications in terms of production inefficiency for grow-out farmers.