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1.
随着生产的快速发展,养蟹业出现了小规格蟹种性早熟和池塘养蟹商品规格小的问题。池塘高密度、集约化的养蟹方式,养成的商品规格更小;大量的人工配合饲料的投入,导致池塘水质恶化,病害频发,药物的滥用造成河蟹品质下降,产品的市场竞争力减弱,经济效益下滑。2005年和2006年以人工集约化池塘饲养作为对比研究,利用湖泊开展生态、优质、高效河蟹养殖,提高成蟹的规格、质量和养殖效益。研究结果显示,湖泊生态养殖对蟹前期生长及后期增重较为有利。2005年和2006年养殖结果统计,湖泊养殖商品蟹的平均规格比池塘人工饲养的平均规格大17%和43%,湖泊的投入产出比是池塘的1.9和3.0倍,且湖泊生态养殖蟹的品质较优,对比试验效果显著。 相似文献
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河蟹一旦发病,感染传播相当快,一些疾病（扣“抖科病”）基本是不可救药,养殖户损失惨重,不少蟹农已到了“望病兴叹”、不敢再养蟹的程度。而部分繁农采取人工生态养殖,历年都较少发病,养殖的图规格大,品质好,效益可观。为此,我认为今后发展河蟹养殖必须走生态养蟹之路。 一、重视水域条件河蟹在天然环境中抗病能力较强,但在集约化养殖的情况下,因养殖密度大、活动范围受限制、加之饲养管理方法缺陷,容易导致蟹病发生。因此选择何种水域条件是很重要的。水域是河蟹增养殖的基本条件,目前养蟹水域种类很多,有池塘、河沟、湖泊… 相似文献
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一、河蟹 江苏地处长江下游，滨江临海，是长江水系中华绒螯蟹的原产地。境内湖泊河道纵横交错，池塘水库星罗棋布，水域资源丰富，有着发展河蟹养殖的得天独厚的条件。白上世纪80年代中期突破河蟹工厂化育苗、90年代全面推广养殖以来，江苏的河蟹养殖一直保持强劲的发展势头，池塘养蟹、湖泊养蟹、稻田养蟹、网围养蟹模式多样，蟹苗繁殖、扣蟹培育、商品蟹养殖配套成龙，河蟹生产、销售产业化经营， 相似文献
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河蟹是我国传统的水产珍品 ,在近年来的水产养殖结构调整中 ,河蟹养殖发展很快。但由于养殖历史较短、技术路线还不够完善等原因 ,目前国内池塘养蟹的亩产一般仅 35ｋｇ左右 ,而且个体规格偏小 ,商品蟹的个体平均只有 60～ 80 ｇ ,超过 1 2 5 ｇ的大规格商品蟹的比例不足 30 % ,严重影响河蟹养殖的经济效益。为此我们从 1 999年1 0月至 2 0 0 1年 5月开展了池塘种草养蟹技术研究 ,采取了从改善池塘养蟹生态环境入手 ,进一步调整种草及管理措施 ,改进投饲方式等技术路线 ,经过二年的试验 ,产量、产值、经济效益达到了预期的结果。现将试验情… 相似文献
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为探索现代河蟹健康生态养殖模式,于2013~2014年在长江口地区,利用生态湿地净化的长江水作为养殖水源,通过开挖深槽沟和种植水草等措施营造"水草森林"的生长环境,运用生态养殖技术,开展了大规格河蟹池塘生态养殖技术的研究和示范试验。试验结果显示:2014年大规格河蟹平均亩产(15亩=1 hm~2,下同)67.5 kg,雄蟹平均规格221 g/只、雌蟹平均规格161 g/只,回捕率在70%以上,达到了增产增量的目的。养殖的商品河蟹经2次药残检测,全部合格,达到水产品安全标准要求。生产期间采用鲜活螺蛳及冰鲜小杂鱼投喂方式大大提高了河蟹的品质,是一种绿色环保健康的养殖模式。 相似文献
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池塘高效养蟹技术初探 总被引：3，自引：0，他引：3
池塘养蟹在我市自1985年开始试养至现在已发展到15万多公顷的养殖规模,成为巢湖渔业的一大特色,有力促进了农村产业结构调整和农民致富。随着河蟹养殖集约化程度的提高和养殖规模的扩大,近几年来,池塘养蟹出现水质恶化、生态环境失衡、商品蟹品质下降、病害频发等问题,导致池塘养蟹总体效益下滑,亏损面扩大,制约了养蟹业的发展。为保持池塘养蟹健康持续发展,探索池塘高效渔业的新路子,我们从1997年开始进行池塘高效生态养蟹试验,现将试验情况报道如下。1 材料与方法11 池塘条件 在池塘养蟹较集中的居巢区钓鱼乡,含山县半湖圩,无为县太平… 相似文献
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中华绒螯蟹是我国重要的水产资源及养殖对象，近年来，河蟹在水产品中所占比重迅速增大。但随着河蟹池塘养殖及围垦高产养殖面积的扩大和大量采用当年繁殖的蟹苗当年养成商品蟹等生产技术方式，在获得高产量的同时，河蟹的商品规格却日渐变小。这种小规格商品蟹的品质及风味远低于翌年养成的大蟹 ，以致小规格河蟹的市场行情一再走低；而大规格河蟹的价位却保持相对较高。因此，摸索出一套简单易行的养殖大规格河蟹生产技术是十分必要的。现根据我站前几年的池塘养殖大规格河蟹技术实践，将此项技术探讨如下。 1材料与方法 1． 1池塘条件 … 相似文献
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池塘养蟹是我国河蟹养殖的重要方式,河南省民权县近年来在推动民权河蟹产业持续发展和技术转型升级方面进行了不懈的努力和探索,通过多方面技术集成,形成了一套池塘规模化循环水生态养蟹技术,实现蟹种培育667 m2均产量200 kg,大规格蟹种比例达87%,667 m2均效益12 000元,成蟹养殖亩均产量105 kg/667 m2,规格蟹比例(雌150 相似文献
11.
Liping Li Rui Wang Wanwen Liang Xi Gan Ting Huang Yan Huang Jian Li Yunliang Shi Honglin Luo Ming Chen 《广西水产科技》2014,(1)
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. 相似文献
12.
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. 相似文献
13.
Controlled infection of Poecilia reticulata Peters (guppy) with Tetrahymena by immersion and intraperitoneal injection 
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下载免费PDF全文 G Sharon M Pimenta‐Leibowitz M C L Vilchis N Isakov D Zilberg 《Journal of fish diseases》2015,38(1):67-74
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). 相似文献
14.
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. 相似文献
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Effect of iodophor disinfection of non‐hardened Salmo trutta eggs on their bacterial and fungus load 下载免费PDF全文
下载免费PDF全文 Franz Lahnsteiner 《Aquaculture Research》2017,48(7):3901-3909
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. 相似文献
16.
T. Citarasu K. Venkatramalingam M. Micheal Babu R. Raja Jeya Sekar M. Petermarian 《Aquaculture International》2003,11(6):581-595
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. 相似文献
17.
Effects of cortisol on hepatic carbohydrate metabolism and responsiveness to hormones in the sea raven,Hemitripterus americanus 总被引：2，自引：0，他引：2
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. 相似文献
18.
Simulation and quantification of enrichment and retention processes in the southern Benguela upwelling ecosystem 总被引：2，自引：0，他引：2
CHRISTOPHE LETT CLAUDE ROY ANNE LEVASSEUR CARL D. VAN DER LINGEN CHRISTIAN MULLON 《Fisheries Oceanography》2006,15(5):363-372
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. 相似文献
19.
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. 相似文献
20.
Gabrielle C. Canonico Angela Arthington Jeffrey K. McCrary Michele L. Thieme 《水产资源保护:海洋与淡水生态系统》2005,15(5):463-483
- 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.