罗氏沼虾

罗氏沼虾江西省水产科学研究所罗氏沼虾课题组罗氏沼虾（Ｍａｅｒｏｂｒａｃｈｉｕｍｒｏｓｅｎｏｅｒｇｉｉ）和我国常见的日本沼虾（即青虾）同属沼虾属，两者之间有许多类似的生活习性和形态结构，它们都是我国目前淡水养殖虾类中的主要优良品种。和青虾相比，罗氏沼虾...     

罗氏沼虾池塘养殖技术及生长研究

罗氏沼虾池塘养殖技术及生长研究郑善坚（浙江萧山浙江水产学校３１１２１４）罗氏沼虾（Ｍａｃｒｏｂｒａｃｈｉｕｍｒｏｓｅｎｂｅｒｇｉｉ）具有生长快、养殖周期短，个体大，经济价值高等特点，受到广大养殖者的青睐。１９９４年仅浙江省罗氏沼虾的养殖面积已有２７０...     

广东罗氏沼虾育苗中幼体大量死亡原因初探

罗氏沼虾（Ｍａｃｒｏｂｒａｃｈｉｕｍｒｏｓｅｎｂｅｒｇｉ）育苗已有一定历史,育苗技术也日趋完善,但近年来广东罗氏沼虾育苗过程中却常出现幼体大量死亡的情况,严重影响生产。由于罗氏沼虾的幼体发育经历复杂的变态过程和较长的时间,许多因子都可能影响其发育变态...     

江都市渔业发展四措施

一、加大结构调整力度,建立渔业区域特色优势进一步调优养殖品种结构。江苏省江都市现有水产养殖面积12郾8万亩(特种水产7郾7万亩),其中罗氏沼虾2郾8万亩,形成虾苗繁殖、成虾养殖、罗氏沼虾全价颗粒饲料加工、罗氏沼虾成品加工、成虾销售的产加销一条龙产业化,“仙宝”牌罗氏沼     

罗氏沼虾池塘高产养殖技术

１９９６年和１９９７年山东省文登市水产研究所在文登市第二淡水养殖试验场利用温泉水进行工厂化育苗成功,并进行了罗氏沼虾池塘养殖试验。１９９６年我们利用８亩新挖池塘,进行罗氏沼虾与鲢、鳙鱼混养,平均亩产罗氏沼虾５０ｋｇ,平均体长８．０ｃｍ,平均亩产鲢、鳙３０ｋｇ。１９９７年我们利用１０亩新挖池塘,进行鱼、虾混养,平均亩产罗氏沼虾７５ｋｇ,平均体长８．５ｃｍ,高产达１００ｋｇ。这些成绩填补了山东半岛地区罗氏沼虾养殖方面的空白,为半岛地区开展罗氏沼虾养殖打下了基础。现将试验情况报告如下。１试验条件１．１…     

罗氏沼虾对维生素C的需求

以每公斤饲料分别添加０、５０、１００、２００、４００、８００ｍｇ维生素Ｃ多聚磷酸酯（ＬＡＰＰ）的半纯化饲料饲养初始体重约５．５２ｇ的罗氏沼虾Ｍａｃｒｏｂｒａｃｈｉｕｍｒｏｓｅｎｂｅｒｇｉ９周。结果表明,添加ＬＡＰＰ使罗氏沼虾的相对增重率显著升高,蜕壳频率增加,蜕壳周期缩短。添加量达到５０ｍｇ／ｋｇ的,可以保证罗氏沼虾正常蜕壳。肝胰脏和血淋巴中的Ｖｃ含量随饲料中ＬＡＰＰ水平的上升而上升,ＬＡＰＰ的添加量达２００ｍｇ／ｋｇ时,肝胰脏中的Ｖｃ达到饱和;而血淋巴中的Ｖｃ含量则随饲料中ＬＡＰＰ水平的上升一直上升。若饲料中缺乏ＬＡＰＰ,则罗氏沼虾全虾的蛋白质和粗脂肪含量下降,而肝胰脏中的粗脂肪含量上升。以增重率为指标,用突破点直线回归法确定罗氏沼虾饲料中Ｖｃ多聚磷酸酯的适宜含量为１１１．９ｍｇ／ｋｇ。     

罗氏沼虾养殖密度与产量关系的研究

罗氏沼虾 (Ｍａｃｒｏｂｒａｃｈｉｕｍｒｏｓｅｎｂｅｒｇｉｉ)个体大 ,生长快 ,食性广 ,肉质好 ,营养价值高 ,是一种优良的淡水养殖品种。 90年代以来 ,罗氏沼虾的养殖在全国范围内迅速发展 ,养殖面积不断扩大 ,养殖技术和单位面积产量也不断提高。不同地区罗氏沼虾的养殖模式大同小异 ,基本上都是采取一次放足苗 ,分批起捕 ,捕大留小的模式。但不同地区罗氏沼虾的养殖密度和单位面积产量则差异很大。为了探讨罗氏沼虾在池塘中的适宜放养密度及放养密度与产量及经济效益的关系 ,我们进行了如下试验。1　材料与方法1 1　池塘条件试验是 199…     

罗氏沼虾配合饲料及其投饲技术的研究

研究了罗氏沼虾必需氨基酸的种类、数量及其比值，提出了罗氏沼虾不同生长期的建议营养指标。报道了罗氏沼虾配合饲料的加工、储存方法以及投饲量、投饲时间、投饲场所等投饲技术。     

罗氏沼虾养殖技术（上）

为了进一步在我国广大农村推广罗氏沼虾养殖基础知识，我们特地编写了“罗氏沼虾养殖技术”一文，供从事罗氏沼虾养殖的生产人员参考。内容包括罗氏沼虾的池塘养殖、罗氏沼虾的人工繁殖以及罗氏沼虾幼虾的培育和运输。     

世界罗氏沼虾养殖概况

世界罗氏沼虾养殖概况魏琦（农业部全国水产技术推广总站）罗氏沼虾Ｍａｃｒｏｂｒａｃｈｉｕｍｒｏｓｅｎｂｅｒｇｉｉ（ｄｅＭａｎ），又称马来西亚大虾，淡水大虾，大长臂大虾，原产于印度太平洋地区，是世界上最大型的热带淡水虾之一，因其具有生长快、食性杂、个体大...     

EFFICIENCY ANALYSIS AND THE EFFECT OF POLLUTION ON SHRIMP FARMS IN THE MEKONG RIVER DELTA

This article investigates the efficiency of intensive, semi-intensive, and extensive shrimp farming practices as well as the difference between the upstream and downstream efficiency of shrimp farms in the Mekong River Delta (MRD), Vietnam. Our article is the first to compare the efficiency of the 3 shrimp practices and investigate the difference between the efficiency of downstream and upstream farms. The efficiency of shrimp farms is measured using group-frontier and meta-frontier analysis on a sample of 292 farms. The results show that, on average, shrimp farms are inefficient; extensive farms are more efficient than intensive and semi-intensive farms; and, controlling for key socio-economic factors, upstream farms are more efficient than downstream farms, suggesting that pollution from upstream farms may influence shrimp farm efficiency. The results give some direction for improvement and some evidence to shrimp farmers and policymakers in the MRD to take the pollution problem seriously and find solutions for more sustainable development.     

Effect of a size-based selection program on blood metabolites and immune response of Litopenaeus vannamei juveniles fed different dietary carbohydrate levels

Blood metabolites in wild and seventh-generation cultivated shrimp were measured to determine how size-based selection could alter the nutritional and immunological conditions of Litopenaeus vannamei. Wild L. vannamei juveniles and a sample of seventh-generation cultured shrimp were acclimated under identical conditions. During 55 days, shrimp were fed a high (HCHO: 44%) or a low (LCHO: 3%) carbohydrate diet for 55 days. Wild shrimp showed a direct relation between dietary CHO and lactate, protein and hemocyte levels indicating that dietary CHO was used for protein synthesis via transamination pathways. In seventh-generation cultured shrimp these parameters were inversely proportional to dietary CHO level, indicating the capacity to synthesize protein from dietary CHO was repressed in cultured shrimp. Farmed shrimp showed a limited capacity to respond to LCHO diets demonstrating high protein dependence in their metabolism and immune response. These results demonstrate that during size-based breeding programs other metabolic process than CHO catabolism can be selected. The incapacity of shrimp to use dietary CHO could limit protein reduction of diets and limit the efforts of the shrimp industry to be ecologically and environmentally profitable.     

Incidence,Growth, and Inactivation of Listeria monocytogenes in Cooked and Peeled Cold-Water Shrimp

ABSTRACT

Cooked and peeled cold-water shrimp (Pandalus jordani) naturally contaminated with Listeria monocytogenes were obtained from a processor for a series of studies to determine the level of contamination and growth characteristics of this bacterium in the naturally contaminated product. L. monocytogenes was isolated from every 25-g sample of individually quick frozen (IQF) shrimp that was tested. The level of contamination in each composite sample ranged from 5 to 16 colony forming units (CFU) per 25 g. When individual shrimp taken from the 25-g sample portions were tested separately, samples positive for L. monocytogenes ranged from 1 of 12 to 5 of 15 shrimp tested. The project also evaluated the effectiveness of three methods to inactivate the bacterium: ozone, chlorine dioxide, and steam as possible product reconditioning strategies. Ozone and chlorine dioxide were both found to be ineffective reconditioning treatments for shrimp naturally contaminated with L. monocytogenes. Experiments with steam conducted at the laboratory and later at the shrimp processing plant verified that shrimp contaminated with L. monocytogenes could be safely reconditioned by steam pasteurization. Steam was used successfully to pasteurize several thousand pounds of contaminated shrimp in the processing plant. When the naturally contaminated product was packaged in either oxygen-permeable or impermeable films and stored at 5°C and 10°C, the product was deemed spoiled by sensory evaluation after 9 days of storage, at which time the L. monocytogenes population were 3 × 10⁴ CFU per g. By comparison, when an isolate (strain 4311) from naturally contaminated shrimp was inoculated onto the pasteurized shrimp at a concentration of 12 cells /25g, the L. monocytogenes population reached 3.0 × 10⁸ per g after 9 days of storage. The pasteurization process used in this study would not be effective in inactivation of Clostridium botulinum. Ready-to-eat-shrimp must therefore be stored below 3°C or frozen.     

褐藻酸钠裂解物对冷冻南美白对虾品质的影响

以褐藻酸钠为原料,采用过氧化氢氧化法制备褐藻酸钠裂解物,分析了裂解物对南美白对虾Penaeus vannamei虾仁质量的效果,并研究了对虾仁冷冻后品质的影响.结果表明,褐藻酸钠裂解物中的分子量大于6 kDa的裂解物HDX-A能有效改善冷冻后水分流失,虾仁经1％的浸泡液处理1h后进行冻藏不同时间后再解冻,HDX-A能够有效地阻止水分流失,从而保持虾仁水分且随时间的延长其保持能力并不减弱,而且随浸泡溶液浓度的增加效果增强.HDX-A主要是通过增加自由水含量而避免了冷冻后虾仁水分和营养流失.HDX-A还可有效地降低冷冻虾仁的蒸煮损失,1.5％处理的样品蒸煮损失最低,整体上蒸煮损失低于20％,120d时仅为15.6％左右,显著低于对照(P＜0.05).HDX-A可通过降低冷冻虾仁水分流失改善了粘弹性和破断力等流变学特性,提高了产品品质,可作为无磷品质改良剂替代复合磷酸盐.     

Technical Efficiency of Shrimp Farming in Bangladesh: An Application of the Stochastic Production Frontier Approach

This study estimates the levels and determinants of farm‐level technical efficiency of shrimp farmers, using the stochastic production frontier function involving a model for technical inefficiency effects. A sample of 90 brackish water shrimp farms were surveyed in the region of Shyamnagar Upazila of the Satkhira District, Bangladesh, to study their economic efficiencies. Data were collected, using a questionnaire survey from September to October 2011. The mean technical efficiency level of the shrimp farmers was estimated at 82%, and thus, farmers operate 18% below the production frontier. The results suggest that the inefficiency effect is significant, and that education, age, non‐farm income and distance of the farm are significant determinants of technical inefficiency. By operating at full technical efficiency levels, shrimp production can increase from the current yield of 225.56 to 265.28 kg/ha. Besides improving technical efficiency, technological progress and extension services (such as dissemination of proper information of the technological practices and further adoption of technological practices) can also contribute to increased shrimp production levels. Finally, quality feed and fingerling at affordable prices need to be ensured to further promote shrimp production.     

A synthetic antibacterial peptide from Mytilus galloprovincialis reduces mortality due to white spot syndrome virus in palaemonid shrimp

White spot syndrome virus (WSSV) isolated from Penaeus monodon was found to be highly infective for the western Mediterranean shrimp, Palaemon sp. Using polymerase chain reaction (PCR), it was demonstrated that such shrimp are not naturally carriers of WSSV. Following challenge with virus, mortality reached 100% 3.5-4 days after injection at 22 degrees C. Incubation of infected shrimp at 10 degrees C totally suppressed the mortality which rapidly developed when shrimp were returned to 18 or 22 degrees C. Preincubation of WSSV with mature synthetic mytilin significantly reduced shrimp mortality with a 50% efficient dose of about 5 microM. Survival of shrimp was not due to the development of an active mechanism of defence as re-injection of WSSV produced the same mortality pattern. Mortality was probably due to WSSV replication as dot blot failed to detect viral DNA in the injection sample but was positive 1 day post-injection. Protection by mytilin was by interaction at the virus level, preventing replication as no WSSV nucleic acid was detected by PCR even after 7 days in shrimp injected with WSSV preincubated with 10 or 50 microM mytilin.     

Willingness to pay for shrimp attributes and evidence of stigma following the Gulf Coast oil spill

Mandatory labeling requirements in the United States require shrimp products to be labelled with certain credence attributes: production process and country of origin. To determine the effects of these requirements in the wake of the 2010 Gulf Coast oil spill, we estimate willingness to pay (WTP) for various credence characteristics (geographic origin and production process) and physical attributes using a Becker DeGroot Marschak experimental auction. Although the results are obtained from a small convenience sample, and hence cannot be generalized, we find that participants are willing to pay premiums of $0.90–$1.23 per half-pound for domestic shrimp (regardless of production method) and $0.60–$1.03 per half-pound for wild-caught shrimp. We also find evidence that Gulf Coast shrimp are stigmatized; controlling for other characteristics, participants are willing to pay $1.03–$1.34 less per half-pound for Gulf Coast shrimp. Overall, credence attributes influence WTP more than physical attributes.     

Presence of multiple viruses in non-diseased, cultivated shrimp at harvest

Histological examinations were carried out with 400 cultivated black tiger shrimp (Penaeus monodon) from 12 commercial rearing ponds from three different areas in Thailand over a period of 3 years. The shrimp were collected at or near harvest time as two arbitrary size groups of 10–20 each from each pond. Aside from size difference, they showed no gross signs of disease and were normally active. Pathognomonic histopathological lesions were found only for hepatopancreatic parvovirus (HPV) or monodon baculovirus (MBV). Although these were relatively frequent, no unusual shrimp mortality had occurred in any of the ponds examined. Severity of these infections was negatively correlated with shrimp size. When grouped together, HPV-infected shrimp gave mean lengths of approximately 6.5 cm that were significantly different from uninfected shrimp at 9 cm length, early in the cultivation cycle while MBV-infected groups of approximately 9 cm length were not readily distinguishable until uninfected shrimp were 10 cm or more, later in cultivation. Thus, HPV infection was correlated with more severe stunting than MBV. In addition to histopathological examination, polymerase chain reaction (PCR) assays for HPV, white spot syndrome virus (WSSV) and infectious hypodermal and hematopoietic necrosis virus (IHHNV) were carried out on one large sample of 240 shrimp from 6 ponds where visible lesions were apparent for MBV only. Surprisingly, 94% of the specimens gave a positive test for at least one of the four viruses. HPV and IHHNV alone or in combination were detected at high prevalence (approximately 60%) despite the absence of visible histological lesions and were confirmed by southern blot hybridization. Although the prevalence of the four viral pathogens was very high, it would normally have gone unnoticed, since normal shrimp are rarely examined for viruses.     

Enhanced growth effects on shrimp (Litopenaeus vannamei) from inclusion of whole shrimp floc or floc fractions to a formulated diet

A growth trial was conducted to determine the effects of inclusion of whole shrimp floc or floc fractions to a control diet on growth and survival of shrimp (Litopenaeus vannamei). The floc sample was collected from marine shrimp culture tanks and partially fractionated by extraction with water, acetone and hexane. A series of diets was manufactured by inclusion of whole floc (intact or ground), each of the fractions or their combination to a control diet. These diets were fed to shrimp (approximately 1.0 g) in an indoor laboratory under flow‐through conditions for 8 weeks. It was found that addition of whole floc (200 g kg^?1) or floc fractions (24–200 g kg^?1) to the control diet improved (P < 0.05) shrimp growth rate without affecting (P > 0.05) shrimp survival (>81.3%). Although inclusion of whole floc reduced the crude protein and crude fat contents and gross energy of the control diet, shrimp fed the whole floc‐supplemented diets obtained the highest (P < 0.05) growth rates (1.01 and 1.03 g week^?1) among the shrimp fed the 11 tested diets including two control (0.81 and 0.85 g week^?1), two commercial (0.45 and 0.71 g week^?1) and five floc‐fraction‐added (0.91–1.00 g week^?1) diets. Many bioactive compounds in the floc that possibly affected shrimp growth were also analysed and quantified.     

Chemical composition and physical properties of salted shrimp paste (Kapi) produced in Thailand

Chemical composition and physical properties of 11 salted shrimp pastes (Kapi) obtained from various places of Thailand were determined. Based on proximate composition, protein constituted the major component (29.44–53.27 %, dry wt. basis). All samples contained 22.77–35.47 % NaCl with A _w of 0.695–0.774. Various formal nitrogen contents (11.96–22.87 mg N/g sample) were in agreement with different degrees of hydrolysis (12.68–20.76 %), suggesting the varying cleavage of peptides among the samples. From electrophoretic study, salted shrimp paste contained a large amount of small molecular weight proteins and peptides. Different samples had different colors with \( \Delta E^{*} \) of 47.10–60.43 and \( \Delta C^{*} \) of 9.46–20.76. The samples had total carotenoid content of 0.54–1.97 mg/g sample. Free astaxanthin, astaxanthin diester and canthaxanthin were the major carotenoids in salted shrimp paste. Thus, salted shrimp paste is a good source of protein and serves as the nutritious condiment.