大力加湖鲟鱼放养场浮游植物及鱼产潜力

2004年5、7、9、12月对大力加湖浮游植物的种类组成结构特征进行了研究。结果表明：大力加湖鲟鱼放养场浮游植物96个种属,密度255.54×10~4 ind．/L,生物量14.166 mg/L。浮游植物季节变化比较明显,密度秋季最高为456.160×10~4 ind．/L,生物量以秋季最高30.105 mg/L。多样性指数变化是夏季＞秋季＞冬季＞春季；均匀度指数变化是冬季＞夏季＞秋季＞春季。全库总鱼产潜力527760 kg,总放养量2804800尾。     

大力加湖鲟鱼放养场浮游动物及鱼产潜力

2004年5、7、9、12月对大力加湖浮游动物的种类组成结构特征进行了研究。结果表明：大力加湖鲟鱼放养场浮游动物59个种属,密度16475 ind．/L,生物量0．3923mg/ L。浮游动物季节变化比较明显,密度春季最高为44200．0ind/L,生物量变化不明显。浮游动物鱼产潜力3666kg,放养量18330尾。     

黑龙江勤得利湾水质理化特征

20 0 3年 5月、 7月、9月和 1 2月对黑龙江勤得利湾水化学特征进行了调查 ,结果表明 :勤得利湾水质良好 ,透明度变幅在 2 5～ 45cm ,pH值变幅在 7 1 4～ 7 5 2 ,水呈中性。水型属重碳酸盐类 ,钙组Ⅰ型 (CcaⅠ)软水。水中主要营养元素含量 ,总氮含量较高平均为 1 0 30mg/L ,磷酸盐含量较低平均为 0 0 1 7mg/L。离子含量以冬季最高 85 5 2mg/L ,春季最低 48 1 1mg/L。水中离子含量高低次序为HCO-3 >Ca2 +>Cl- >Na+s+K+>Mg2 +。探讨了水体的营养类型和利用。     

大力加湖鲟鱼放养场鱼类区系组成

本文报道抚远大力加湖鲟鱼放养场鱼类区系组成。2004年对抚远县大力加湖鲟鱼放养场鱼类区系组成进行调查。调查结果表明：大力加湖有鱼类6目15科74种,系由6个区系复合体组成。     

西北地区水库网箱鲟鱼精养六法

正鲟鱼是近年来刘家峡水库养殖发展的新品种,以其营养价值高、肉无杂刺,受到广大消费者青睐。养殖前景好,经济效益高,养殖规模逐渐扩大。鲟鱼属亚冷水性鱼类,其生长的最适温度为18～25℃,溶解氧的含量要求在5 mg/L以上,具有生长快、产量高、抗病能力强,以及养殖技术易掌握等优点。本文介绍鲟鱼网箱精养技术,从鱼苗放养、饲料投喂、日     

新疆蘑菇湖水库浮游生物种群结构及鲢鳙鱼产力的研究

2016年4月(丰水期)、7月(平水期)和11月(枯水期)于水体上(距水面0.5m)、中、底(距水底0.5m)层分别采等量水混匀,调查新疆蘑菇湖水库的理化因子状况及浮游生物的种群结构,综合评价水库水质营养状况,并根据浮游生物现存量估算滤食性鲢鳙的鱼产力,以期通过合理放养鲢鳙降低水库过量氮磷含量,达到生态治理的目的。结果显示:采样期间蘑菇湖水库平均pH为8.33、平均水深4.55m、总磷含量0.29mg/L、氨氮含量4.94mg/L,水质为富营养型水库;共鉴定浮游植物90种,浮游动物36种,平均生物量分别为6.72mg/L和3.79mg/L,鱼产力分别为鲢468.18t和鳙720.13t。鲢和鳙的理论合理最大放养量分别为27.41万尾和70.33万尾,鲢∶鳙比例约为1∶2.57。     

铜、锌对褐牙鲆鳃丝Na↑（+）-K↑（+）-ATPase活力的影响

以幼体褐牙鲆(Paralichthys olivaceus)为研究对象.Cu2+浓度梯度设置为0.10 mg/L、0.20 mg/L、0.50 mg/L和1.00 mg/L;Zn2+浓度梯度为1.00 mg/L、2.00 mg/L、5.00 mg/L和10.00 mg/L.实验周期为20 d.结果表明,在6 d内Cu2+(除1 mg/L处理组外)、Zn2+各处理组褐牙鲆鳃丝Na+-K+-ATPase活力随取样时间变化显著(P<0.05),且呈峰值变化,在24 h时达到最大值,然后缓慢下降;6～15 d,各处理组酶活力趋于稳定;而1 mg/L Cu2+处理组在12 h时酶活力达到最大值,3～15 d酶活力趋于稳定.2种重金属离子各处理组对鳃丝Na+-K+-ATPase活力的影响在同一取样时间差异显著(P<0.05),其影响程度与重金属离子浓度呈负相关,且1 mg/L Cu2+和10 mg/L Zn2+处理组在6～15 d酶活力与对照组差异不显著(P＞0.05).同时2种重金属离子在1～15 d内对褐牙鲆鳃丝Na+-K+-ATPase活力的诱导率表现为Zn2+(1 mg/L)＞Cu2+(1 mg/L).     

镧对稀有鮈鲫肝胰脏抗氧化酶活性及MDA含量的影响

以氯化镧(LaCl3?7H2O）为试验毒物,以稀有鮈鲫（Gobiocypris rarus）为试验材料,采用21 d慢性毒性试验（La3+含量分别为0.00、0.04、0.08、0.16、0.32、0.80 mg/L）,通过检测稀有鮈鲫肝胰脏中超氧物歧化酶(SOD)、过氧化氢酶(CAT)活性和丙二醛(MDA)含量,研究了镧暴露胁迫对水生动物抗氧化系统的影响,以期从抗氧化生理响应的角度探讨稀土元素镧对水生动物的毒理机理。结果显示,与对照组相比,0.04～0.32 mg/L试验组肝胰脏SOD活性出现一定程度降低(P＞0.05),但0.80 mg/L组SOD活性出现一定程度上升(P＞0.05);0.04～0.32 mg/L试验组肝胰脏CAT活性较对照组出现一定程度降低(P＞0.05),但0.80 mg/L组CAT活性出现一定程度上升(P＞0.05),且0.80 mg/L组CAT活性显著高于0.04～0.32 mg/L组(P＜0.05);0.04～0.16 mg/L试验组肝胰脏MDA含量较对照组出现一定程度降低(P＞0.05),0.32mg/L组MDA含量略微升高(P＞0.05),0.80 mg/L组MDA含量显著高于对照组(P＜0.05),也显著高于其它La3+暴露组(P＜0.05)。研究表明,一定浓度的La3+暴露胁迫会对环境中水生生物抗氧化系统产生不利影响。     

几种常用渔药对三疣梭子蟹Portunus trituberculatus(Miers)稚蟹的急性毒性试验

采用常温静水实验法.对Ⅰ～Ⅱ期梭子蟹稚蟹(平均体长0.2～0.3 cm)进行急性毒性试验,结果表明:在水温26.2～27.8℃F,6种渔用药物对梭子蟹Ⅰ～Ⅱ期稚蟹的96 h半致死浓度(96 h LC50)分别为硫酸铜1.4 mg/L、纤虫清2.5 mg/L、清苔净16 mg/L、二氧化氯3.7 mg/L、强力杀菌消毒剂4.2 mg/L、二溴海因36.8 mg/L;安全浓度(Sc)分别为硫酸铜0.47 mg/L、纤虫清0.62mg/L、清苔净4.1 mg/L、强力杀菌消毒剂1.1 mg/L、二氧化氯1.1 mg/L、二溴海因13 mg/L.梭子蟹对上述药物的敏感性分别为硫酸铜＞纤虫清＞三氯异氰尿酸钠＞二氧化氯＞二溴海因＞清苔净.其中硫酸铜、纤虫清的安全浓度相对较低,在梭子蟹养殖过程当中应谨慎使用.     

几种重金属离子对淡水石斑胚胎及仔鱼的毒性试验

本实验研究了Hg^2 、Cd^2 、Cu^2 和Pb^2 四种重金属离子淡水石斑胚胎及仔鱼的毒性，四种离子毒性大小顺序均为：Hg^2 ＞Cd^2 ＞Cu^2 ＞Pb^2 。对仔鱼24h的半致死浓度为0.36mg/L、1.75mg/L、5.85mg/L和3.80mg/L；48h的半致死浓度0.17mg/L、1.10mg/L、2.75mg/L和1.70mg/L。对仔鱼的安全浓度为：Hg^2 0.011mg/L、Cd^2 0.1mg/L3、Cu^2 0.10mg/L、Pb^2 0.18mg/L。     

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.