大面积推广小体积高密度网箱养鱼技术总结

1992年向阳山水库进行小体积、高密度网箱鱼养,共推广202只网箱,1m×1m×1.1m规格的68只、1.4m×1.4m×1.1m规格的126只、2 m×2m×1.1m的8只,总面积346.96m~2。生产商品鱼65160kg,平均单产187.81kg/m~2,增重倍数6.63,饵料系数2.3,投入产出比1∶1.41,每平方米利税近500元。此结果表明,小体积、高密度网箱养鱼技术已由试验阶段发展到大面积推广阶段。     

投饵网箱养鱼促进温杖子水库渔业高速增产的生态经济效益分析

温杖子水库按养鱼水面单位面积承受２２００ｋｇ／ｈａ网箱鱼的负载量设置网箱，建立以网箱养鱼为重要环节的水库新型渔业生产结构体系。三年中，水库水面鱼产量（含网箱鱼产量）由１４５．５ｋｇ／ｈａ上升到２６６．７１ｋｇ／ｈａ，年总产量增长１８．３倍；渔业投入资金年利润率达７１．９％；网箱养鱼的投入总能量转换效率提高了６．０３－６．３６％。合理开发和保护了水库渔业资源，促进了温杖子水库渔业的高速增产。     

小体积高密度网箱养鱼技术要点

网箱养鱼是世界上许多国家采用的一种集约化养殖技术，传统的大网箱养鱼，因水体交换不良，溶氧不足，生产潜力受到一定局限。 8以下的小体积网箱养鱼，换水率高，生产能力大。我市自 1995年在中、小型水库开展小体积高密度网箱养鱼，经过多年探索，已形成一套适应内陆山区推广的高产模式，产鱼 150～ 213 kg/m3。现将有关技术简介如下。 1网箱结构与设置 1.1网箱结构 用 4× 3聚乙烯线织成，规格为 1 m× 1 m× 1.3 m或 2 m× 2 m× 1.3 m。网箱底部铺设一层密网布 (100目 / )，作为饵料台。投饵管用直径 15 cm塑料管或毛竹管 (中间竹…     

灵寿县再现网箱养鱼新高潮

自从黄壁庄水库网箱养鱼被取缔后 ,灵寿县全县一度出现网箱养鱼空白。自 2 0 0 1年开始 ,王快水库部分养殖户迁到横山岭水库养殖对我县沿库移民村起到了示范带动作用 ,2 0 0 2年横山岭水库网箱曾一度达到5 0 0箱。为防止水体富营养化 ,今年网箱数量较前两年有所下降 ,但由于今年鱼价上涨 ,一个 6m× 6m× 3m的鲤鱼网箱年纯利润少则 5 0 0 0元 ,多则 1万元不等。这样的诱惑力 ,使百姓的养殖热情空前高涨。目前 ,网箱养鱼除横山岭水库外 ,已相继出现在中小型水库中 ,燕川水库已发展到 5 0多箱 ,后山水库已发展到 5箱 ,刘库池水库也正在筹备之…     

从浮游植物看金堂水库水质的演变

金堂水库位于重庆市壁山县正兴乡 ,集雨区为农田浅丘陵 ,集雨面积 19 6km2 。正常蓄水时 ,库容 112 0万m3,面积 88 8hm2 ,平均水深 12 6m ,最大水深 2 7m ,库水交换系数 :0 2 <а <0 3。是集灌溉、旅游、养鱼于一体的典型浅丘地区中小型水库。水库从 1986年开始网箱养鲤 ,由此产生的大量残饵和鱼粪进入水体 ,使水体富营养化进程急剧加快 ,给水库渔业生产造成了严重危害 ,1989年 1月因水质恶化引起网箱鱼死亡 2 0吨。此后有关专家对金堂水库水质调查 ,认为网箱养鲤对金堂水库水质影响严重[1,2 ] ,水质恶化 ,溶氧缺乏。 1995年 ,停止网箱养…     

水库网箱安置的水域位置选择

古田县拥有2座大型水库,养殖面积达6267hm2。1976年,古田溪水库在全省率先进行水库网箱养鱼试验并获得成功。近年来,随着水口水库电站的建成,黄田、水口两镇的库区群众兴起了网箱养鱼热潮,2004年古田县网箱养鱼达2万箱,年产鱼3000多t,占全县养殖总产量的20%。实践证明,网箱养鱼     

罗非鱼小网箱养殖试验报告

小网箱养鱼（即小体积高密度网箱养鱼技术）是美国奥本大学水产博士鲁迪·史密脱先生３０多年来一直研究和推广的一项水产养殖高产高效技术，一般每立方米水体产鱼可达１５０－３００公斤。１９９１年该项技术引入我国，１９９７年结合全国农牧渔业丰收计划项目，我区在南城县石溪水库（一座约５００亩水面的小〈一〉型水库）投放共计９０个小网箱３００平方米，进行罗非鱼养殖试验，并获得成功。材料１．网箱：２×３聚乙烯线编织，网目２５、３公分两种，网箱规格为１×１×１２（２０个）和２×２×１７（７０个）两种。２．浮动网…     

浅谈水库网箱安置的水域选择

古田县拥有两座大型水库,水库养殖面积达9．4万亩。1976年,古田溪水库就在全省率先进行水库网箱养鱼试验并获得成功：在水库网箱养鱼生产中,网箱安置的水域位置选择得当,箱鱼长得快,经济效益高;反之,不但箱鱼长得慢,有的共至被洪水袭击全军覆没。笔者根据多年的工作实践,认为正确选择网箱安置的水域位置主要应从安全性、针对性和地理方位等五个方面进行考虑。本文就这一问题做一具体论述。     

山东省岸堤水库鱼病调查及防治

岸堤水库位于山东省蒙阴县城东部,是山东省第二大水库,2003年鲤养殖网箱(5m×5m)500个,鲫养殖网箱200余个,鲢等滤食性鱼养殖网箱近9 000个。笔者于2003年4—9月,走访调查了岸堤水库的铁城、石桥、重山、石宝玉等村庄23户鲤、鲫养殖户,调查网箱253个,统计分析了这6个月内岸堤水库吃食性鱼类鲤和鲫的发病情况,并对鲤粘孢子虫病和2龄鲫营养障碍症进行了防治探讨,以期为今后水库网箱养鱼的防病和治病工作提供参考。     

丁店水库网箱养殖草鱼技术要点

荥阳市丁店水库是郑州市第2大中型水库,控制流域面积150km2,设计库容6065万m3,水库正常养殖面积153.3公顷。1990年前,由于采用传统方式进行养殖生产,水库年出鱼仅有10吨,单产仅10kg/667m2,产量低,效益低。1990年开始网箱养鱼,水库中设置网箱投喂全价颗粒饲料养殖成鱼,库叉设拦网养殖花、     

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).     

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.     

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.