甲氰菊酯对黄鳝的急性毒性试验

采用常温静水实验法,进行甲氰菊酯对黄鳝苗种的急性毒性试验,结果表明:甲氰菊酯对黄鳝苗种半致死浓度为59×10-9(96hLc50),安全浓度为5.9×10-9。黄鳝对甲氰菊酯敏感。     

“克虫王”对大口鲶鱼苗的急性毒性试验

为了验证新药“克虫王”在水产养殖中对鱼类的毒性,选用“克虫王”两种剂型渔用杀虫剂对大口鲶鱼苗进行了急性毒性试验。试验结果表明:B_2型“克虫王”对全长4.9cm大口鲶鱼苗的24h、48h、72h半致死浓度(TLm)分别为1.20×10~(-6)、0.88×10~(-6)、048×10~(-6),安全浓度为0.14×10~(-6)。C型“克虫王”对大日鲶鱼苗的24h、48h、72h半致死浓度(TLm)分别为4.65×10~(-6)、3.60×10~(-6)、1.15×10~(-6),安全浓度为0.64×10~(-6)。     

太湖微囊藻对鱼类毒性影响的研究

本文首先通过血凝实验证明太湖的微囊藻具有蓝藻毒素，在此基础上进行鱼类染毒实验，采用全细胞藻体和经冻解的藻液给鱼类染毒，结果发现全细胞输送灌胃染毒对鱼类（乌鳢）的毒性较小，半致死浓度ＬＣ５０×９６ｈ为３５０ｍｇ／ｋｇ；以冻解藻液腹腔注射染毒对鱼类（草鱼）毒性较大，一次染毒４小时的半致死浓度ＬＣ５０×４ｈ为４４０ｍｇ／ｋｇ，二次染毒６小时半致死浓度ＬＣ５０×６ｈ为２５０ｍｇ／ｋｇ，说明太湖微囊藻属于毒藻，毒性级别可定为中等。     

两种药物对脊尾白虾各期(氵蚤）状幼体的毒性试验

采用静水实验法进行甲醛和孔雀石绿对脊尾白虾 (Exopalaemoncarinicauda)各期状幼体 (Z1～Z6)的急性毒性研究。结果表明 :在pH值为 7 9± 0 5、水温 (2 6 0± 0 5 )℃的条件下 ,甲醛对脊尾白虾Z1～Z6的半致死浓度 (48hLC50 )分别为 176× 10 -6,16 7× 10 -6,15 0× 10 -6,16 7× 10 -6,113× 10 -6,5 5× 10 -6,安全浓度 (Cs)分别为 30× 10 -6,17× 10 -6,32× 10 -6,11× 10 -6,4× 10 -6,9× 10 -6;孔雀石绿对脊尾白虾Z1～Z6的 4 8hLC50 分别为 0 4 5 1× 10 -6,0 4 4 8× 10 -6,0 5 91× 10 -6,0 4 4 0× 10 -6,0 380× 10 -6,0 15 8× 10 -6,Cs分别为 0 0 6 9× 10 -6,0 0 5 8× 10 -6,0 10 2× 10 -6,0 0 90× 10 -6,0 0 71× 10 -6,0 0 34× 10 -6。其中Z5和Z6对以上药物的敏感性较高     

在轮虫培养中用敌百虫杀灭桡足类的试验

针对鱼、虾、蟹人工苗种生产中经常遇到的由于轮虫中混杂桡足类导致育苗失败的实际情况,探讨利用轮虫和桡足类对晶体敌百虫忍耐性的差异,在不影响轮虫生长、繁殖的情况下彻底清除桡足类的方法。结果表明:轮虫和桡足类对敌百虫的忍耐性有较大的差异,轮虫和桡足类的96h敌百虫安全浓度分别为2.0mg/L和0.2mg/L;致死浓度分别为3.0mg/L(96h)和0.4 mg/L(72h);在敌百虫添加浓度0.5~2.0mg/L条件下,敌百虫对轮虫繁殖率的影响随添加浓度加大而增加,但这一影响是可逆的,一般在2~3d后即可恢复正常。在苗种生产实际中,将敌百虫处理浓度定为1.0~1.5mg/L较为适宜。     

江西进贤湖泊浮游动物

1993年-1994年对进贤湖泊浮游动物调查分析.共采到浮游动物85种,隶属于58属.平均生物量0.7112mg/L优势种属群为原生动物的沙壳虫、似铃壳虫、轮虫类的龟甲轮虫,枝角类的秀体、透明、象鼻,桡足类的无节幼体和桡足类幼体.鱼产力2.808×10-3k/m2.     

对中华绒螯蟹生态育苗池中桡足类控制的初步研究

比较了蛛虫速灭、鱼虫恨和强力混杀3种渔药对桡足类和中华绒螯蟹溞状幼体的急性毒性。试验结果表明,蛛虫速灭对桡足类的96h半致死添加量为0.011mL/m3,鱼虫恨为0.036mL/m3,强力混杀精为0.014mL/m3,蛛虫速灭对桡足类的杀灭能力最强;对中华绒螯蟹溞状幼体Ⅰ期的急性毒性鱼虫恨最大,蛛虫速灭最小。蛛虫速灭在0.18～0.20mL/m3的剂量下,对溞状幼体毒性低,幼体能正常变态,可用于蟹苗池桡足类的控制。强力混杀精对桡足类和中华绒螯蟹溞状幼体的毒性很接近,鱼虫恨对中华绒螯蟹溞状幼体的毒性大于对桡足类的毒性,两者均不适宜在中华绒螯蟹生态池控制桡足类。     

三种常用化学消毒剂对牙鲆仔稚鱼的急性毒性研究

选用3种化学消毒剂对牙鲆仔稚鱼进行急性毒性试验。结果表明,高锰酸钾对牙鲆仔鱼的24 hLC504、8 h LC50和安全浓度分别为1.678×10-6、1.382×10-6和0.281×10-6,对牙鲆稚鱼的24 h LC50、48 hLC50和安全浓度分别为2.555×10-6、1.789×10-6和0.263×10-6;甲醛对牙鲆仔鱼的24 h LC50、48 h LC50和安全浓度分别为25.821×10-6、10.671×10-6和0.547×10-6,对牙鲆稚鱼的24 h LC50、48 h LC50和安全浓度分别为33.959×10-6、17.046×10-6和1.288×10-6;聚维酮碘对牙鲆仔鱼的24 h LC50、48 h LC50和安全浓度分别为15.744×10-6、8.163×10-6和0.658×10-6,对牙鲆稚鱼的24 h LC504、8 h LC50和安全浓度分别为25.802×10-6、21.286×10-6和4.346×10-6。牙鲆仔稚鱼对3种化学消毒剂的敏感性依次为:高锰酸钾>甲醛>聚维酮碘,并且牙鲆仔鱼分别对3种消毒剂的敏感性均大于牙鲆稚鱼分别对3种消毒剂的敏感性。最后依据本试验结果,作者对牙鲆疾病防治中消毒剂的使用进行了探讨。     

厦门港尖额真猛水蚤室内培养的研究

由厦门港潮间带筛选的小型桡足类——尖额真猛水蚤(Euterpe acutifrons),在鱼、虾育苗中具有明显的应用价值。进行周年室内培养试验,单一雌体生命周期67天,培养两个半月后,个体数达15万个,平均培养密度3689个/升,日增殖率0.149。夏季怀卵10次,间隔3—9天,总怀卵量174个;冬季怀卵3次,间隔12—16天,总怀卵量86个。使用单种饵料——微型黄藻的异胶藻(Heterogroea sp)周年培养该种桡足类是可行的。饵料浓度以100×10~4个/毫升较适,当350×10~4个/毫升时繁殖尚顺利,但在850—1680×10~4个/毫升以上,生长繁殖受抑制,浓度太高甚至死亡。     

史氏鲟养殖技术讲座:苗种培育(Ⅰ)

1 史氏鲟仔幼鱼对环境因素的适应性 大部分鱼类幼体比成体对环境的要求高,对于史氏鲟的养殖,即使水质符合渔业养殖用水标准也不能掉以轻心,冈为鲟鱼仔、幼鱼对水质极为敏感。史氏鲟对非离子氨的敏感性高于一般淡水鱼类,仔鱼96小时半致死浓度为0.063 mg/L,稚鱼96小时半致死浓度为0.17 mg/L。仔鱼养殖水体中铁的浓度小于0.5 mg/L为宜,对于10cm以上的幼鲟,水中铁的浓度以小于1mg/L为宜。史氏鲟养殖用水的pH值应在6.5-9.0为宜。当溶氧高于6 mg/     

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.     

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.     

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.     

Involvement of gonadal steroids in final oocyte maturation of white perch (Morone americana) and white bass (M. chrysops): in vivo and in vitro studies

Plasma estradiol-17 (E₂), testosterone (T), 17,20-dihydroxy-4-pregnen-3-one (DHP) and 17,20,21-tri-hydroxy-4-pregnen-3-one (20-S) levels were measured by radioimmunoassay (RIA) in white perch (Morone americana) and white bass (M. chrysops) that were induced to undergo final oocyte maturation (FOM) with human chorionic gonadotropin (hCG). Plasma DHP levels increased in females of both species in association with oocyte germinal vesicle migration (GVM) and germinal vesicle breakdown (GVBD) and decreased thereafter. Plasma 20-S levels also increased with oocyte GVM in white bass, but were several-fold lower than DHP levels. Circulating E₂ and T levels were greatest during GVM and GVBD in both species and decreased to low levels during oocyte hydration and ovulation. Follicles from white perch and white bass which received a priming injection of hCG in vivo, produced both DHP and 20-S in vitro after exposure to hCG and their oocytes underwent GVBD. Ovarian incubates from unprimed fish of either species produced only E₂ and T and their oocytes did not complete GVBD. Oocytes from unprimed bass, but not perch, matured when follicles were exposed to hCG in vitro. Both trilostane and cycloheximide blocked in vitro production of DHP and 20-S and oocyte GVBD by white perch follices. DHP and 20-S were equipotent inducers of FOM in the GVBD bioassay. None of several other structurally-related steroids tested were effective within a physiological range of concentrations. These results indicate a role for DHP and 20-S in the control of FOM in white perch and white bass.