黄河干流陕西段鱼类种类组成及群落多样性

为了解黄河陕西段鱼类种类组成及群落结构,2013-2015年调查了黄河陕西段鱼类资源。结果显示:黄河陕西段有鱼类7目15科58种,其中鲤科鱼类最多为36种,占总种类数的61.1%,较20世纪80年代减少了6种。优势种有4种,数量占渔获物总数量50.3%,生物量占65.8%。分析渔获物组成和群落多样性,黄河陕西段鱼类年龄、个体规格小型化趋势明显,不同河段鱼类群落存在明显空间差异,府谷段多样性指数最高,群落结构稳定,港口段丰富度指数最高,资源种类较多,港口和壶口的鱼类群落结构没有相似性。     

2009年陕西省渔业水域生态环境监测与评价

<正>一、监测渔业水域内渔业资源及渔业生产状况黄河陕西段主要为黄河鲤、黄河鲶和鲫鱼等鱼类的产卵场和索饵场。对这些点进行监测,对于黄河干流陕西段重要经济鱼类资源及地方种属的保护有着重要的意义。     

黄河陕西段浮游动物群落结构特征研究

于2013年5月对黄河陕西段浮游动物的群落进行了系统调查,并结合相关数据,分析了黄河陕西段浮游动物群落结构空间变化特征。调查共获取浮游动物4个大类,12个种,在种类组成中占主导地位的类群是轮虫。黄河陕西段浮游动物平均密度为6.6个/L,变化范围为0.2~21.0个/L,浮游动物平均生物量为14.8μg/L,变化范围为0.1~56.3μg/L。前节晶囊轮虫(Asplanchna priodonta)和萼花臂尾轮虫(Brachionus calyciflorus)为黄河陕西段浮游动物优势种类。浮游动物Shannon-Weiner多样性指数平均值为1.48,变化范围为1.00~2.12。浮游生物物种多样性指数评价结果表明,黄河陕西段浮游动物群落结构趋于简单化,水质受污染程度为中等,河流生态保护亟待加强。     

黄河班多段鱼类多样性初步研究及保护对策

黄河班多段位于青海省兴海县境内,是黄河上游主要鱼类分布区之一.2011年4-11月对黄河班多段鱼类资源进行了调查.设采样点4个,分别在鱼类生长繁殖的重要时期使用不同网具采捕4次,并结合走访调查及鱼类样本的实验室鉴定与分析,重点研究鱼类种类、鱼类多样性、丰富度及均匀度,并提出了保护对策.结果表明,本次调查共采集鱼类10种、138尾,均为土著鱼类,种类占黄河上游青海段鱼类近1/2,班多段鱼类多样性相对黄河上游青海段其它水域较高,鱼类组成与黄河上游青海段其它水域相似,种类相对比较丰富,涉及多种保护鱼类,但每种鱼的个体均匀度较差,抗外界扰动的能力差.     

黄河陕西段2种主要经济鱼类资源调查及其生物学性状分析

为了解黄河陕西段主要经济鱼类的资源现状,于2013年对赤眼鳟和乌鳢进行了资源调查和生物学性状分析。结果显示,赤眼鳟主要分布在府谷、韩城至港口一带,资源量占渔获物量的5.91%,年龄组成主要以1+和2+为主,雌雄比例为1∶2.25。乌鳢主要分布在合阳洽川以下水域,资源量占渔获物量的4.66%,年龄组成主要以2+和3+为主,雌雄比例为1∶1.25。两种经济鱼类资源量占比较低,摄食水平相对低下,种群结构较简单。因此,在加强黄河陕西段主要经济鱼类野生资源恢复的同时应积极创建规范化养殖模式以提高整体资源量。     

黄河陕西段兰州鲇资源现状及历史变动

兰州鲇作为黄河中上游特有濒危大型经济鱼类,在黄河陕西段具有一定量的分布,然而关于该鱼类在该区段的种群数量及资源情况的数据资料较为缺乏。为此,本文主要对该区段野生兰州鲇于2013年-2015年间的资源状况进行了调查,分析兰州鲇的种群分布区域、种群数量和结构、产卵场分布情况、资源量变化情况、最新的濒危状况以及不同水域兰州鲇的自然种群生态学等。结果显示:兰州鲇目前仅在黄河中上游水域及陕北入黄河的河流下游有分布;黄河陕西段兰州鲇产卵场分布在合阳县洽川、合阳县大西高铁、大荔鲁安、大荔县雨林、潼关县港口等五个区域;与上世纪80年代相比,兰州鲇资源量有所减少,个体小型化,食物严重缺乏,种群数量受到了严重破坏。因此,迫切需要采取有效措施,对兰州鲇种质资源进行保护。     

黄河兰州市区段秋季鱼类资源现状调查

于2014年秋季在黄河兰州市区段设置7个采样断面对鱼类资源进行了调查。结果显示:调查的鱼类有13种,隶属于4目5科。其中鲤科鱼类占优势,有9种,占总种类数的69.23%。鲤科鱼类中鲦数量最多,占总渔获物数量的28.41%,鲤鱼的体重最大,平均为312g/尾,占总渔获物重量的83.78%。黄河兰州市区段鱼类区系具有5种区系复合体特征。本次调查结果表明黄河兰州市区段鱼类种类明显减少,渔获物中小型鱼类数量占很大优势。建议加大流域生态环境保护力度,适时进行经济鱼类的增殖放流。     

黄河河南段非漂流性卵鱼类产卵场现状调查

为了掌握黄河河南段鱼类产卵场的分布现状,2013-2015年的每年3-7月,采用卫星GPS定位,实地走访渔民,采集鱼卵和仔稚鱼,捕获并解剖分析繁殖亲鱼,同步进行理化因子测定和环境指标监测。结果表明,黄河河南段鱼类规模产卵场共有30处,主要分布在河边浅滩、河流消落区和河心岛等水生生物资源丰富、适合非漂流性卵鱼类产卵孵化的水域。监测调查270d,采集主要鱼类标本1 156尾,各产卵场的鱼类优势种组成差异明显。产卵经济鱼类有鲤(Cyprinus carpio)、鲫(Carassius auratus)、鲶(Silurus asotus)、鳊(Parabramis pekinensis)、泥鳅(Misgurnus anguillicaudatus)、黄颡鱼(Pelteobagrus fulvidraco)、赤眼鳟(Squaliobarbus curriculus)共计7种。黄河南段主要经济鱼类产卵场的分布位置及范围规模存在明显的地域差异。为保护黄河南段经济鱼类及其产卵场,提出了具体的保护措施。     

沿黄滩区黄河乌鳢池塘套养技术模式探索与分析

陕西省沿黄滩区洽川黄河湿地是全国最大的黄河湿地，面积达117万hm^2（167万亩）。该地水草丰腴，生态环境良好，生长着一种名贵的淡水经济鱼类——黄河乌鳢。2008年经农业部批准，成立了黄河洽川段乌鳢国家级水产种质资源保护区。2009～2011年，笔者在陕西新民家鱼原种场进行了黄河乌鳢生态养殖技术探索性试验。     

黄河鱼类资源保护目标的研究

黄河是我国的第二大河,近些年来黄河的生态系统健康受到了威胁,鱼类资源遭到了严重破坏。作者于2002—2007年对黄河的水生生物及鱼类进行了调查研究。调查共采集到鱼类标本41种,其中珍稀濒危保护鱼类4种,地方性保护鱼类11种,结合调查的实际情况,根据黄河流域现存鱼类资源的稀有性和其在水域中的作用地位,提出关键性保护鱼类的代表性鱼类,提出生态流量、水质和水环境3个关键性保护指标。     

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.     

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.     

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.     

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.     

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).