施氏獭蛤稚贝中间培育与海区养殖试验

施氏獭蛤稚贝中间培育和海区养养殖试验在雷州市覃斗镇英岭村海区进行,结果显示:经过35d的中间培育,稚贝壳长、壳高、壳厚平均值分别为23.1、11.2、6.2mm,平均重量1.8g,成活率达53%。经过一年的海区养殖试验,壳长、壳高、壳厚平均值分别为68.2mm、33.5mm、19.3mm,体重达40g以上。     

黄河口毛蚶稚贝池塘中间培育技术研究

<正>毛蚶(Scapharca subcrenata)是黄河口地区重要的海产经济贝类,受生境破坏及过度捕捞等因素影响,近年来其资源和产量大幅下降。针对毛蚶稚贝海区成活率较低、生长缓慢等问题,开展了毛蚶稚贝池塘中间培育技术研究,主要在池塘使用自主研制的网笼进行了试验。本试验投放毛蚶稚贝437.4kg,平均壳长3.4mm、壳高2.3mm,使用网笼180组,经过45d培育,共收获稚贝2155万粒,共计1728kg,成活率98.5%,平均壳长10.1mm,增长了197.1%。     

厚壳贻贝人工繁殖技术的研究

厚壳贻贝(Mytilus coruscus)是我国贻贝的主要养殖品种,其苗种主要依靠天然苗种和半人工采苗获得。2006年浙江海洋学院于嵊泗县石柱育苗厂,首次突破了厚壳贻贝规模化全人工繁殖和稚贝海区中间培育技术。研究结果表明,厚壳贻贝亲贝通过室内强化培养,经人工催产可获得成熟受精卵,受精率可达95%。在水温16℃时,受精卵在受精后25min出现第一极体,受精后39h50min发育至直线绞合幼虫期,胚胎孵化率达92%,在水温15.8～21℃的条件下,经39d室内人工培育,获平均壳长0.694mm的附着稚贝1304.7×104ind;附着稚贝经102d海区中间培育,获平均壳长13.95mm的稚贝404.46×104ind,海区保苗成活率达31%。该研究结果为今后厚壳贻贝大规模苗种生产奠定了重要理论和技术基础。     

文蛤工厂化人工育苗技术(三)

8．1 稚贝室外中间育成将越冬后的稚贝(壳高约在1mm),按一定数量放入事先改造好的中间育成池的网箱内进行培育管理。     

黑蝶贝苗种中间培育技术的初步研究

以黑蝶贝野生群体人工繁育苗种为研究材料,探索了大、小两种规格和不同吊养深度对黑蝶贝苗海区中间培育的影响。将壳长、体质量分别为(4.12±0.019)mm、(0.07±0.008)g,(2.02±0.012)mm、(0.03±0.005)g两种规格黑蝶贝吊养于2m、4m、5m区,每组黑蝶贝500枚,养殖水温23.09~29.77℃,养殖海区水深8~10m。每隔30d随机抽取50枚贝苗测量壳高、壳长、壳宽、体质量。经180d中间培育,壳长(4.12±0.019)mm的黑蝶贝生长速度明显大于壳长(2.02±0.012)mm的黑蝶贝,表明壳长(4.12±0.019)mm的黑蝶贝出池移入海区养殖较理想。同一规格贝苗在2m、4m、5m养殖水层的成活率差异不显著(P0.05),而3个不同养殖水层中不同规格贝苗养殖成活率差异显著(P0.05)。该研究结果为进一步开展黑蝶贝苗种人工繁育提供了重要参考。     

青蛤生产性育苗及中间培育技术研究

为解决青蛤养殖生产所需苗种,在借鉴泥蚶生产性育苗技术基础上,重点突破了青蛤亲贝强化培育与人工催产技术,幼虫饵料单胞藻培育技术,青蛤苗种中间培育与清涂除害技术,系统掌握生产性育苗及中间培育技术,实现了青蛤苗种的规模化生产。2003～2005年累计培育平均壳高2mm的稚贝74．574亿粒,经中间培育后出池商品仔贝49．842亿粒,中间培育成活率达到66．84%。生产性育苗净利润163．82万元,中间培育总利润776万元,平均每平方千米获利15 089元。     

菲律宾蛤仔垦区育苗技术优化及其对池塘理化环境、浮游植物和稚贝生长的影响

为改进菲律宾蛤仔垦区育苗技术,设置一口池塘(A)培育高密度浮游植物并定期添加至育苗池(B),未添加藻类育苗池(C)作为对照,比较了A、B、C以及邻近自然海区(D)的水体、沉积物、浮游植物状况和池塘B、C中稚贝生长情况。结果显示,池塘A、B、C之间水质和沉积物各指标无显著性差异,但三者水体中盐度、pH、溶解氧、氨氮、硝酸盐氮、活性磷酸盐和沉积物中有机碳、硫化物与自然海区D差异显著;浮游植物密度ABCD,但仅A、D间差异显著;池塘B稚贝壳长和密度均显著大于池塘C。这表明垦区与自然海区环境差异大,而育苗期间通过外源补充藻类能提高稚贝的生长率和成活率,进而提高菲律宾蛤仔垦区育苗成功率。     

虾夷马粪海胆的海区渡夏、室内中间培育及工厂化养成↑（*）

１９９３年７月～１９９７年５月,在夏季采用网袋、网箱开展虾夷马粪海胆Ｆ２代稚海胆的海区渡夏,壳径日平均生长量比室内提高３３．６％～６１．６％;采用网箱平面培育方法进行Ｆ２代稚海胆室内中间育成和Ｆ３代稚海胆室内中间育成中试,壳径的日平均生长量随时间呈下降趋势,为０．５３×１０－２～１．４６×１０－２ｃｍ／ｄ,体重日平均生长量呈上升趋势,介于２．３２×１０－２～１０．７２×１０－２ｇ／ｄ之间,培养中密度过大会降低海胆的成活率并导致疾病发生;采用立体水槽开展陆地工厂化养成,经１３个月,海胆壳径由１．１６ｃｍ增至５．９８ｃｍ,体重由０．４７ｇ增至６１．０ｇ,性腺指数达１８．０％。     

波纹巴非蛤人工育苗技术

本试验参照波纹巴非蛤在自然海区中的生长繁殖以及幼体发育习性,开展土池生态育苗.在室内水泥池进行催产和浮游期以及附着后稚贝的培育.在稚贝生长至壳长1.Omm的幼贝后,移人准备好的土池中培育,解决了稚贝在水泥池中培育遇到的饵料和环境条件制约瓶颈.通过3年的摸索,在2010年度,培育出平均壳长9.70毫米,平均体重0.117...     

毛蚶人工育苗最佳附着基的选择

为了找出毛蚶育苗当中最佳附着基,本文对几种附着基进行了对比试验,试验采用四种对比,即油泥、网衣、网片、直接附着在池壁上。结果发现,毛蚶人工育苗最佳附着基为潮间带表层油泥。稚贝生长快,成活率高,苗整齐,壳不挂脏。经过26d培育,成活率及生长速度分别为:油泥68%,平均壳长1.3 mm;网衣54%,平均壳长1.1mm;网片47%,平均壳长1.1mm;直接附着在池壁42%,平均壳长0.9mm。     

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.     

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.     

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.     

Effects of cortisol on hepatic carbohydrate metabolism and responsiveness to hormones in the sea raven,Hemitripterus americanus

The sea raven, Hemitripterus americanus, is a sit-and-wait, low metabolic rate, marine teleost. The objective of this study was to determine i) whether cortisol implantation (50 mg. kg^-1) for 7 days altered hepatocyte metabolism, and hepatocyte responsiveness to epinephrine, glucagon and insulin, and ii) whether 8 weeks of food-deprivation modified the above response. Cortisol implantation significantly increased hepatocyte total glucose production and oxidation from alanine compared to the sham group. There was no cortisol effect on glycogen breakdown, suggesting that the activation of other pathways, including gluconeogenesis, are required to account for the increased glucose production. Epinephrine-mediated (10^-5M) glycogen breakdown and insulin-mediated (10^-8M) total glucose production were enhanced in hepatocytes of cortisol implanted sea ravens, but there were no change in any glucagon (10^-7M) effects. The enhanced glycogen breakdown in the absence of similar increases in total glucose production with epinephrine indicates mobilization of carbohydrate reserves for endogenous use by the liver. Food-deprivation for 8 weeks significantly decreased condition factor, plasma cortisol concentration and liver glycogen content in the sea raven, but had no effect on plasma glucose concentration. Hepatocyte total glucose production and flux rates from alanine increased significantly with food-deprivation. Moreover, food-deprivation increased responsiveness of total hepatocyte glucose production to the actions of glucagon and insulin, but not to epinephrine; none of these effects were modified by cortisol implantation. Our results indicate that cortisol in the sea raven exerts both a direct and an indirect or permissive effect on hepatocyte metabolism by modifying hepatocyte responsiveness to epinephrine and insulin stimulation. Cortisol implantation did not modify the effects of glucagon or food-deprivation in this species.     

Simulation and quantification of enrichment and retention processes in the southern Benguela upwelling ecosystem

Important environmental processes for the survival and recruitment of early life stages of pelagic fishes have been synthesized through Bakun's fundamental triad as enrichment, concentration and retention processes (A. Bakun, 1996, Patterns in the Ocean. Ocean Processes and Marine Population Dynamics. San Diego, CA, USA: University of California Sea Grant). This conceptual framework states that from favourable spawning habitats, eggs and larvae would be transported to and/or retained in places where food originating from enrichment areas would be concentrated. We propose a method for quantifying two of the triad processes, enrichment and retention, based on the Lagrangian tracking of particles transported within water velocity fields generated by a three‐dimensional hydrodynamic model. We apply this method to the southern Benguela upwelling ecosystem, constructing putative maps of enrichment and retention. We comment on these maps regarding main features of the circulation in the region, and investigate seasonal variability of the processes. We finally discuss the results in relation to available knowledge on the reproductive strategies of two pelagic clupeoid species abundant in the southern Benguela, anchovy (Engraulis encrasicolus) and sardine (Sardinops sagax). Our approach is intended to be sufficiently generic so as to allow its application to other upwelling systems.     

Effects of capture,loading density and transport stress on the mortality,physiological responses,bacterial density and growth of rohu <Emphasis Type="Italic">Labeo</Emphasis><Emphasis Type="Italic"> rohita</Emphasis> fingerlings

This study evaluated the effects of three levels of loading density (200, 300 and 400 g L⁻¹) and four levels of duration (1, 3, 6 and 9 h) on the mortality, plasma cortisol and chloride levels and growth of rohu Labeo rohita fingerlings in a transport simulation. While total immediate mortality was low (4–12%), delayed mortality was high (27–49%). Initial capture and handling were found to constitute the most stressful phase as indicated by elevated plasma cortisol. The levels of cortisol continued to rise at 6 and 9 h after transport, with the highest level observed at 9 h after transport. The level of plasma chloride fell after transport across all density levels and treatment durations. Specific growth rate (SGR, %/day) and total bacterial density (cfu/g) were not different between and within treatments, and between treatments and the controls. This study demonstrates that transport has a profound effect on the stress responses of rohu fingerlings. Although the level of immediate mortality was low, the higher level of delayed mortality has serious implications in terms of production inefficiency for grow-out farmers.     

The effects of introduced tilapias on native biodiversity

• 1. The common name ‘tilapia’ refers to a group of tropical freshwater fish in the family Cichlidae (Oreochromis, Tilapia, and Sarotherodon spp.) that are indigenous to Africa and the southwestern Middle East. Since the 1930s, tilapias have been intentionally dispersed worldwide for the biological control of aquatic weeds and insects, as baitfish for certain capture fisheries, for aquaria, and as a food fish. They have most recently been promoted as an important source of protein that could provide food security for developing countries without the environmental problems associated with terrestrial agriculture. In addition, market demand for tilapia in developed countries such as the United States is growing rapidly.
• 2. Tilapias are well‐suited to aquaculture because they are highly prolific and tolerant to a range of environmental conditions. They have come to be known as the ‘aquatic chicken’ because of their potential as an affordable, high‐yield source of protein that can be easily raised in a range of environments — from subsistence or ‘backyard’ units to intensive fish hatcheries. In some countries, particularly in Asia, nearly all of the introduced tilapias produced are consumed domestically; tilapias have contributed to basic food security for such societies.
• 3. This review indicates that tilapia species are highly invasive and exist under feral conditions in every nation in which they have been cultured or introduced. Thus, the authors have concluded that, despite potential or observed benefits to human society, tilapia aquaculture and open‐water introductions cannot continue unchecked without further exacerbating damage to native fish species and biodiversity. Recommendations include restricting tilapia culture to carefully managed, contained ponds, although exclusion is preferred when it is feasible. Research into culture of indigenous species is also recommended.

Copyright © 2005 John Wiley & Sons, Ltd.