利用光合细菌等综合措施预防斑节对虾暴发性流行病试验

近几年来，我市养殖对虾大面积暴发传染性流行病，而且发病率高、病害来得早、范围广、损失大是我市养虾史上所罕见，使我市对虾养殖业又陷入困境，广大虾农因之大伤元气而情绪纸落，对搞好今后的对虾养殖生产信心不足。为了探索养虾防病新技术，为广大虾农提供成功范例，针对虾病主要是由于环境等外界不良因子的诱发，     

北方地区凡纳滨对虾亲虾越冬及幼体培育技术初探

从广西地区引进5月龄和7月龄的凡纳滨对虾10000对,从中选出健康无病的成虾作为后备亲虾8000对,放入工厂化车间培育4个月,探索亲虾在北方地区越冬培育技术和性腺发育过程,分析理化因子对亲虾性腺发育的影响.此外,总结提出凡纳滨对虾幼体生产技术.     

饵料和养殖密度对中国对虾幼虾生长及存活率的影响

在实验用虾遗传背景一致的情况下,分析了3种饵料(配合饲料、冰冻鲜鱼肉和活卤虫)和4个不同的养殖密度对小水体中国对虾幼虾生长和存活率的影响。结果表明,饵料和饲养密度对中国对虾幼虾生长及存活率有显著影响。在饵料、养殖密度单因子实验及饵料和养殖密度相结合的双因子实验中,幼虾的生长均表现出极其显著的差异(P<0.01),活卤虫对幼虾生长的效应尤为突出。而养殖密度对中国对虾的行为生物学、个体间体重增量均有影响。随着养殖密度的提高,中国对虾增重变慢;同时,个体间体重增量差异变大。随着养殖密度的增加,中国对虾幼虾的存活率呈下降趋势,但不同饵料对存活率影响变化幅度较大,波动在58.1%～85.2%之间,其中投喂活卤虫养殖密度为50尾/桶的存活率最高(85.2%);投喂配合饵料4个养殖密度梯度的存活率变化不明显;而投喂冰冻鱼肉4个养殖密度梯度的存活率变化较大。因此,采用合适的饵料和养殖密度,能够提高中国对虾的生长速度,提高对虾养成存活率,改善生长过程中对虾群体体长、体重的整齐度。     

南美白对虾早起死亡综合征防控措施

<正>近年来南海沿岸各地养殖南美白对虾排塘率高、成功率低,这使养殖者觉得对虾难养,不少人弃虾改养其他品种。许多养虾场放养南美白对虾虾苗后5~30天就陆续发病大量死亡,甚至全军覆灭。据各地反映,认为主要原因是对虾早期死亡综合征引起的。由于连续受虾病严重困扰,对虾产业几乎陷入全线低迷。虾苗滞销,虾料降量,虾塘降租,加工厂高价收虾或无虾可收。面对对虾疾病严重威胁养虾业,怎样使对虾养殖业渡过难关?在此,笔者提出对虾早期死亡综合征防控的措施,供养殖者参考。一、对虾早期死亡综合征病因与症状外国专家所称的早期死亡综合征(EMS)或急性肝     

对虾“早期死亡综合征”研究现状

<正>对虾"早期死亡综合征"(Early Mortality Syndrome,EMS),也称作急性肝胰腺坏死综合征(Acute Hepatopancreas Necrosis Syndrome,AHPNS),最早报道是2009年,以后日益严重,影响中国、越南、马来西亚和泰国等养虾主产国。对虾"早期死亡综合征"影响的主要对虾种类包括凡纳滨对虾、斑节对虾和中国明对虾在内的     

广东省对虾康养殖与可持续发展的对策

虾病是对虾殖业的最大危害，每年因虾病全球对虾养殖的产量减少一半，损失几百亿元人民币。１９９３年，由于对虾病毒性疾病的暴发，我国对虾养殖业出现大幅度滑坡，使年产对虾２０多万吨、年创汇５亿美元，成为世界养虾大国的我国对虾产业走入低谷，随后，为了恢复和发展对虾养殖业，广大科技工作和虾农做了大量的科研攻关和细致的工作，付出了艰辛的劳动，取得了积极的成果，但在全国范围内，对虾养殖业仍没有恢复到虾病暴发流行前的水平，并存在一定的差距，虾病依然是对虾养殖业的瓶颈。本对广东省对虾养殖的现状和问题，提出对虾健康养殖与可持续发展的对策与措施。     

早期投喂对虾料促进罗氏沼虾生长的试验

早期投喂对虾料促进罗氏沼虾生长的试验高桂明钱金铭汤正虞（上海市松江县水产良种场，２０１６１６）最近几年，我国的对虾养殖因遭受流行性虾病的严重危害而跌入低谷。由此同时，大型经济虾类罗氏沼虾的养殖却异军突起，发展非常迅速。本试验根据罗氏沼虾食性广、易养殖...     

日本囊对虾早期胚胎发育的研究

正日本囊对虾(Marsupenaeus japonicus)隶属于甲壳纲、十足目、对虾科、囊对虾属,分布在印度—西太平洋热带、非洲东海岸、马来西亚、日本、朝鲜、中国东南沿海等海域,我国90年代开始对其进行人工养殖。日本囊对虾耐干露、色泽艳丽,长途运输存活率达90%以上,通常鲜活销售,有较高的经济价值,深受水产品市场和养殖者欢迎。日本囊对虾的早期发育阶段是复杂的生命周期中最为敏感的阶段。盐度和温度是自然水体分布范围的主要决定因子,影响着日本囊对虾的生长与繁殖,尤其是影响日本囊对虾胚胎发育的最重要的非生物因素。多年来,凡纳滨对虾进口亲虾的价格节节攀升,而养殖成功率却不断下     

使用漂白粉改善对虾池水环境的研究

对漂白粉的杀菌效果，对对虾毒性、对单胞藻和虾池水环境因子的影响进行了试验研究。池水有效氛浓度为０．３～０．５×１０（－６），不会对对虾和池内单胞藻造成危害，并可使氨氮含量降低，ＰＨ值增加，对溶解氧、化学耗氧量等无明显影响。治疗虾病时，先使用漂白粉，然后投喂药饵，可取得较好效果。     

K↑（+）对中国明对虾幼虾生存及耗氧率、窒息点的影响

采用单因子静态急性毒性实验方法,研究盐度为6的海水中不同K 浓度对中国明对虾(Fenneropenaeue chinensis)幼虾存活率的影响,并测定中国明对虾幼虾在不同K 浓度水质中的耗氧率及窒息点。结果表明:(1)K 含量过低或过高,均会成为影响中国明对虾幼虾生存的限制因子,中国明对虾幼虾对K 的生存适宜范围为16.00-165.80 mg/L,K 质量浓度低于16 mg/L时,中国明对虾幼虾的存活率随K 浓度的增加而上升;而当K 质量浓度高于165.80 mg/L时,中国明对虾的存活率随K 浓度的增加而下降。(2)水中不同K 浓度会对中国明对虾幼虾的耗氧率产生影响,在K 质量浓度分别为20 mg/L6、0 mg/L和120 mg/L,水温为(18.5±0.5)℃条件下,中国明对虾幼虾5 h平均耗氧率分别为(0.801±0.059)mg/g.h、(0.719±0.057)mg/g.h、(0.828±0.047)mg/g.h。(3)不论是低K 浓度组还是高K 浓度组,中国明对虾幼虾窒息点均明显高于正常海水K 浓度组,当水温为(19.4±0.1)℃,中国明对虾幼虾在K 质量浓度为20 mg/L、60 mg/L和120 mg/L时的窒息点分别为(1.469±0.006)mg(O2)/g、(1.350±0.005)mg(O2)/g、(1.496±0.006)mg(O2)/g。     

苏北浅滩中部海域春秋季口足目和十足目虾类分布特征

根据2010年5月和9月苏北浅滩如东海域虾类调查资料,研究了苏北浅滩中部海域口足目和十足目虾类种类组成和多样性的时空分布,探讨了主要优势种密度对总优势种密度的影响,并结合该海区地形地貌、水文环境等因素对虾类多样性进行了分析。结果表明,在2次调查中,共鉴定出十足目18种,口足目2种。依据相对重要性指数IRI的计算,得出该海域春季主要优势种为葛氏长臂虾(Palaemon gravieri),秋季为哈氏仿对虾(Parapenaeopsis hardwickii)。尽管春季各站位平均种类数稍高于秋季,但秋季虾类种间分布较均匀,致使该海域虾类重量和尾数多样性指数(H')均值秋季(1.59,1.85)皆高于春季(1.13,1.57)。不同生态类群虾类种类变化形成季节更替,更替率为55%。黄海冷水团和长江冲淡水的季节变化是影响该海域虾类种类生态类群和多样性分布的主要水文因素。     

Impact of farm management on expression of early mortality syndrome/acute hepatopancreatic necrosis disease (EMS/AHPND) on penaeid shrimp farms in Thailand

Asian shrimp farming industry has experienced massive production losses due to a disease caused by toxins of Vibrio bacteria, known as early mortality syndrome/acute hepatopancreatic necrosis disease (EMS/AHPND) for the last 5 years. The disease can cause up to 100% cumulative pond mortality within a week. The objective of this study was to identify factors associated with AHPND occurrence on shrimp farms. A case–control study was carried out on shrimp farms in four provinces of Thailand. Factors related to farm characteristics, farm management, pond and water preparation, feed management, post‐larvae (PL) shrimp and stock management were evaluated. Multivariable logistic regression analysis identified factors affecting AHPND occurrence at the pond level. Chlorine treatment, reservoir availability, use of predator fish in the water preparation, culture of multiple shrimp species in one farm and increased PL stocking density contributed to an increased risk of AHPND infection, while delayed first day of feeding, polyculture and water ageing were likely to promote outbreak protection. Additionally, the source of PL was found to be associated with AHPND occurrence in shrimp ponds, which requires further study at the hatchery level. Identification of these factors will facilitate the development of effective control strategies for AHPND on shrimp farms.     

对虾养殖生态环境的研究现状和展望

依据近几年的有关参考文献对有关对虾生态环境的研究成果及存在的问题进行了评述。从生态学方面阐述了对虾养殖生态系统的特点，提出对虾养殖生态环境中理化因子的研究应该更注意与生物及微生物因子的结合。     

吕泗渔场沿岸海域春夏季虾类群落特征

为研究吕泗渔场沿岸海域虾类群落结构特征,利用2010年春季(5月)和夏季(9月)在吕泗渔场沿岸海域开展渔业资源调查获取的资料,分析了虾类的种类组成、多样性空间分布及群落结构特征,并对其影响因素进行探讨。结果表明:吕泗渔场沿海海域春夏两季共出现虾类18种,其中春季11种,夏季15种;春季优势种为葛氏长臂虾、日本鼓虾和鲜明鼓虾,夏季优势种为哈氏仿对虾和中华管鞭虾。研究表明:吕泗渔场沿岸海域虾类春季以暖温性生态类群为主,夏季以暖水性生态类群为主。吕泗渔场沿岸虾类种类数和多样性指数较高的站位主要集中在调查海域的外侧。运用聚类和多维标度对群落结构的相似性进行分析,结合水深等环境因子对吕泗渔场沿岸海域虾类的群聚类型进行了讨论,吕泗渔场沿岸虾类群落结构季节变化明显、空间差异显著,水团变化、地形、水深是导致吕泗渔场沿岸海域春夏季虾类群落结构时空差异的主要原因。     

Population dynamics of the brown shrimp Crangon crangon L., in shallow areas of the German Wadden Sea

Settlement, growth and mortality of the brown shrimp, Crangon Crangon L., were studied in the north Frisian Wadden Sea over a period of 19 months to fill existing gaps regarding the species' life cycle, and thereby to clarify points related to the fishery. Settlement of postlarval shrimp in the shallow areas occurred in three batches: in May; during summer; and an overwintering batch. Compared with an earlier model based on laboratory-derived data, a new growth model based on field data predicts similar growth rates for the earlier phase of the shrimp life cycle, but higher rates for the later stages of the cohorts. Mean growth rate of the different cohorts over the size range sampled was 0.23 ± 0.08 mm day^?1. Of the factors tested, only temperature significantly influenced growth rates. Preliminary estimates of instantaneous total mortality values for shrimp cohorts from these shallow areas ranged from 0.03 to 0.12 day^?1. Salinity explained most of the variation in mortality rates, but this most likely indicates an indirect effect of depth on emigration. The cumulative effects of growth rates estimated from the new model and lower losses through predation could imply a higher contribution of winter eggs to the autumn fishery. This, however, needs further evaluation to properly quantify the trade-offs between settlement and recruitment to the fishery, as well as the growth and mortality rates.     

对虾配合饵料与虾病防治关系的研究

对虾配饵中动、植物蛋白比接近1:1为宜,如果动物蛋白不足,对虾生长发育不良,易感染各种疾病。配饵中添加鱼油试验经生物统计表明,鱼油是对虾增重的第一限制因子。配饵中缺乏鱼油,对虾食欲不振,会引起消化生理代谢障碍。对虾配饵原料质量如油脂氧化酸败与原料霉变及霉变产生的毒素,对对虾生长极其不利。不仅使虾体瘦弱,抗病力减弱,而且死亡率比对照组明显增高。因此,对虾配饵精选原料是保证配饵质量、减少发病率、提高成活率的关键因素。     

PURCHASING SHRIMP FOR AT-HOME CONSUMPTION: THE RELATIVE IMPORTANCE OF CREDENCE VERSUS PHYSICAL PRODUCT FEATURES

Consumers have become increasingly concerned with the quality, safety and production features of food. Certain population segments will pay more for food products carrying a label identifying credence features that consumers cannot evaluate, even after consumption. Seventy-nine market research questionnaires were completed by consumers purchasing live shrimp at two harvest sales at a University of Florida pond aquaculture facility. A conjoint analysis experiment was included to quantify the utility value and relative importance of seven different shrimp product physical and credence features: species, size, refrigeration state, product form, purchase price, country of origin label, and production method label. Both credence features had positive impacts on shrimp product utility, with country of origin label conferring higher positive utility than any other shrimp feature. Utility associated with wild-harvested shrimp was slightly higher than the utility of farm-raised shrimp. These results provide justification of seafood industry support for mandatory country of origin labeling.     

Economic characteristics of extensive shrimp farms in the Mekong delta

Abstract

Extensive forms of shrimp aquaculture have become an important source of income for farm households in the brackish water region of the Mekong Delta, Vietnam. The economic and production characteristics of farms are discussed in this paper, based on a 1997 farm survey, with particular emphasis on shrimp farming practices. Two types of shrimp fanning practice were observed, one based on natural recruitment of seedstock with few supplementary inputs, and the other based on relatively high cash investments in Penaeus monodon seedstock and other inputs. Households practising monodon culture made significantly more income, but faced high risk associated with shrimp mortality. An investigation of the factors affecting monodon yields indicated that investment in higher quality inputs had a positive effect on yield and income. However, further research is needed on the extent to which management can reduce risk of shrimp mortality by investing in such premium quality inputs.     

Strain and dose infectivity of Vibrio parahaemolyticus: the causative agent of early mortality syndrome in shrimp

Diseases of shrimp have contributed to billions of dollars of economic loss in the aquaculture industry. Newly emerging strains of the bacterium Vibrio parahaemolyticus produce a condition in shrimp called early mortality syndrome or acute hepatopancreatic necrosis disease. Three different V. parahaemolyticus strains were evaluated for their respective pathogenicity on shrimp, Litopenaeus vannamei, when the bacterial strains were grown under various laboratory conditions prior to inoculating shrimp. For each trial, feed was inoculated with a known concentration of bacteria and then fed to the shrimp. The early mortality syndrome strain of V. parahaemolyticus was the most lethal resulting up to 100% mortality within 24 h after being introduced to shrimp via a single feeding. The other two strains of Vibrio, one isolated from the environment and the other from a human clinical case, resulted in 0% and 30% mortality within 96 h respectively. The concentration of the early mortality syndrome strain of V. parahaemolyticus that the shrimp were exposed to directly correlated with mortality rate, which allowed for lethal or sublethal short‐term disease challenge assays to be established. Infiltration of haemocytes was also evident in the midgut caeca of shrimp infected with the early mortality syndrome strain of V. parahaemolyticus, which has not been previously reported.