关于鲍的养殖技术之二海上筏式养鲍技术要点

福建省连江县从１９８９年开始规模化养鲍，目前，全县已有海陆养鲍场上百家，其中兼有育苗生产的４０多家，养鲍的方式有陆地和海上养殖两种，陆上养鲍量达２０００万粒，海上养鲍量达３０００万粒，其中海上养殖多采用筏式方法，现将海上筏式养鲍技术要点介绍如下： 一、养殖海区的选择 养鲍理想的海区必需是水深、水流畅通、水质清新、盐度高、透明度好、温度相对稳定、附近无河流、水质不受工业和生物（特别是赤潮）污染的海区。 １．水深：养鲍海区不宜过浅，水深要求在低潮时保持在１０ｍ左右，最好在１５—２０Ｉｎ之间。 ２．水温：…     

降低海上筏式养鲍死亡率的优良措施

为了促进鲍鱼海上筏式养殖方式健康、持续、稳定地发展,养殖单位应采取一切行之有效的方式方法,控制病害的发生和蔓延,使养殖鲍鱼的死亡率降到最低限度。现笔者结合生产实践,略论降低海上筏养鲍鱼死亡率的优良措施,以供广大养鲍者参考。     

降低海上筏式养鲍死亡率对策

鲍养殖经过多年试验,海上筏养方式已备受养殖者的喜爱。但随着养殖规模的扩大,也逐渐出现了大面积死亡现象,使养鲍单位蒙受巨大经济损失。为此,笔者结合生产实践,提出降低筏养鲍死亡率对策。供广大养鲍者参考。     

降低海上筏式养鲍死亡率之良策

鲍鱼的养殖经过多年的试验,海上筏养方式已备受养殖者的喜爱,但随着养殖规模的扩大,也逐渐出现了大面积的死亡现象,使养鲍单位蒙受巨大的经济损失.为了促进筏养鲍鱼健康、持续、稳定发展,笔者结合生产实践,略论降低筏养鲍鱼死亡率的优良措施,以供广大养鲍者参考.     

影响北方筏式养鲍生长及成活因素的探讨

目前我国北方地区鲍养殖方式主要是底播增殖和筏式养殖，并已形成一定的规模。但当前养鲍存在突出问题就是鲍的生长速度慢，养成周期长，海上成活率低，极大影响养鲍的生产效益。一般情况下，鲍鱼人工养殖约需３年，海上养成成活率仅７０％左右。我市鲍养殖业起步较早，发展较快，技术较为成熟，特别是筏式养鲍积累了一些经验，与其他地区相比，养成周期缩短半年左右，养成成活率提高１０％以上，平均亩年效益达 ４００００多元。现就我们在生产中的实践经验，对影响的生长及成活的主要因素进行初步探讨。１ 环境条件对鲍生长及成活的影响１…     

专家建议实行海陆交替养鲍模式

目前我养鲍模式大致归纳为六种:海上筏式养殖、陆上工厂化养殖、坑道养殖、底播养殖、潮间带养殖以及海底沉箱养殖等。国家海洋局第二海洋研究所陈全     

影响北方筏式养鲍生长及成活因素的探讨

目前我国北方地区鲍鱼养殖方式主要是底播增殖和筏式养殖,并已形成一定的规模。但当前养鲍存在突出问题就是鲍鱼生长速度慢,养成周期长,海上成活低,极大影响养跑生产效益。一般情况下,鲍鱼人工养殖约需三年,海上养成成活率仅70％左右。山东省荣成市鲍鱼养殖业起步早,发展快,技术较为成熟。特别是筏式养鲍经验典型,效益显著,与其他地区养鲍效果相比,养成周期缩短半年左右。养成成活率提高10％以上,平均亩年效益达40000多元。现就我们在生产中的实践经验,对影响鲍鱼生长及成活的主要因素进行初步探讨。一、环境条件对鲍鱼生长及…     

降低海上筏式养鲍死亡率之良策

鲍鱼的养殖经过多年的试验，海上筏养方式已备受养殖的喜爱，随着养殖规模的扩大，也逐渐出现了大面积的死亡现象，使养鲍单位蒙受巨大的经济损失，究其原因，错综复杂，既有自然因素，也有人为因素。为了促进筏养鲍鱼健康、持续、稳定发展，建议养殖单位应当采取一切行之有效的方法，控制病害的发生和蔓延，使筏养的鲍鱼的死亡率降到最低限度，现笔结合生产实践，略论降低筏养鲍鱼死亡率的良策。以供广大养鲍参考。     

提高北方筏式养鲍效益措施

随着人民生活质量的提高,国际市场对鲍的需求量巨增,目前,世界市场鲍的缺口量在万t以上,市场前景广阔,因此,鲍的人工养殖在我国得以迅猛发展,海上筏式养鲍备受养殖者的喜爱。     

浅海筏式养鲍技术要点

鲍的养殖是我国重要的海水养殖产业之一.浅海筏式养鲍,具有养殖设施简单、养成时间短、成本低、产品质量好等特点,目前已成为我国最主要的鲍养殖方式.……     

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).     

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.     

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.