瓯江海南沼虾溯江幼虾资源的初步调查

本文报道了瓯江海南沼虾溯江幼虾资源的现状。瓯江当年生海南沼虾的溯江幼虾在每年6月底开始出现,11月后消失;高峰期在8月中、下旬。据统计:1988年仅青田县沙埠至石溪口江段的海南沼虾幼虾产量就达8700公斤。估算年蕴藏量在1.75万公斤以上,且目前处于基本稳定状态。     

Bycatch in a tropical schooling – penaeid fishery and comparisons with a related, specialised trawl regime

Abstract  The bycatch in a tropical Australian banana prawn, Penaeus merguiensis (de Man), fishery is described and contrasted with the closely related tiger prawn, Penaeus semisulcatus De Haan and Penaeus esculentus Haswell, fishery. Most of the similarity between banana prawn fishery catches was accounted for by three teleost species constituting 51.4% of the total bycatch weight. The bycatch assemblage structure of this fishery was significantly different ( P  <   0.05) from the adjoining tiger prawn fishery. The banana prawn fishery had a higher mean bycatch catch rate from shorter duration trawls, but lower estimated total annual bycatch (1502 t yr⁻¹) than the longer duration trawls of the tiger prawn fishery (20 073 t yr⁻¹). This study provides new data for quantifying bycatch and improving the accuracy of quantitative risk assessments currently being used to demonstrate sustainability of bycatch populations. The information will be incorporated into collaborative development of a long-term monitoring programme.     

Assessment of requirement values for essential amino acids in the prawn, Marsupenaeus japonicus (Bate)

The requirements of juvenile prawn, Marsupenaeus japonicus (Bate), 0.79 g initial body weight, for essential amino acids (EAA) were evaluated based on the daily increase of each EAA in the whole body when the prawn was maintained on a diet with a high nutritive value (a casein‐squid protein‐based diet). The quantities of each EAA needed daily for growth and maintenance of prawn are conceived to correspond to the daily requirements of this prawn species for EAA. Therefore, these requirement values of respective EAA should be supplied from dietary proteins. To determine these values, protein and amino acids of the whole body of the prawn were quantified before and after feeding experiments, and the quantities of respective EAA needed to meet the requirements were estimated based on the EAA profile of the whole body protein of prawn. As a result, the contents of EAA in dietary proteins (%) needed to meet the requirements of the prawn for EAA were assessed to be: threonine (2.3), methionine (1.3), valine (2.4), isoleucine (2.3), leucine (3.4), phenylalanine (2.6), lysine (3.2), histidine (1.1), arginine (2.9) and tryptophan (0.6), respectively, when the prawn are fed 50% protein diet with 90% protein digestibility at a ration size of 2% (% of body weight).     

应用SSR和SRAP标记构建青虾遗传连锁图谱

采用SSR和SRAP标记结合拟测交策略构建青虾(Macrobrachium nipponense)遗传连锁图谱。共有175个标记(含27个SSR、148个SRAP标记)分布在53个连锁群上。每个连锁群含2~8个标记,其中不少于3个标记的连锁群有35个,连锁对18个,平均每个连锁群的标记数为3.3个;连锁群长度在6.7~91.2 cM之间,相邻标记间最大间隔为49.0 cM,最小为1.4 cM,平均间隔为13.1 cM。青虾框架图谱长度为997.2 cM,图谱观察总长度为2 270.5cM,根据估算,青虾遗传连锁图谱预期长度为4 380.6 cM,图谱的覆盖率为51.83%。本研究构建了青虾遗传连锁图谱,该图谱也是淡水虾蟹类第一张遗传连锁图谱,可为青虾QTL定位、基因克隆、遗传选育等提供指导,并为进一步构建高密度的青虾遗传连锁图谱奠定了基础。     

Using the Sustainable Livelihoods Framework to Identify Constraints and Opportunities to the Development of Freshwater Prawn Farming in Southwest Bangladesh

A conceptual framework, drawn from an approach to poverty reduction known as the sustainable livelihoods approach (SLA), is applied to understanding the role of freshwater prawn, Macrobrachium rosenbergii, farming in gher (modified rice fields with high, broad peripheral dikes) systems in southwest Bangladesh. Gher farming potentially allows incorporation of a wide variety of crops together with prawn, fish, dike crops, and rice culture. The analysis shows how, in a gher farming context, sustainable livelihoods are achieved through access to a range of livelihood assets, which are combined in the pursuit of prawn farming strategies. The study used the SLA framework as a diagnostic tool to identify ways of strengthening the livelihoods of the prawn farmers.     

THE SUSTAINABLE LIVELIHOODS APPROACH TO THE DEVELOPMENT OF FRESHWATER PRAWN MARKETING SYSTEMS IN SOUTHWEST BANGLADESH

A conceptual framework, drawn from an approach to poverty reduction known as the Sustainable Livelihoods Approach (SLA), is applied to understanding the role of freshwater prawn (Macrobrachium rosenbergii) marketing systems in southwest Bangladesh. Freshwater prawn marketing potentially provides economic returns and social benefits to the rural poor. Although the potential benefits are great, a number of constraints were identified for the long-term sustainability of prawn marketing systems. The study used the SLA framework as an analytical tool to identify ways to strengthen livelihoods of prawn traders and associated groups.     

The production economics of freshwater prawn (Macrobrachium rosenbergii) farming in Hawaii

Detailed cost-return of freshwater prawn farming in Hawaii is estimated for farms ranging in size from a minimum of 1 acre to a maximum of 100 acres. Major factors affecting cost and revenue are discussed. Freshwater prawn farming in Hawaii is profitable at the existing average annual production of 3 000 pounds/acre and at the existing average farm price of $3.00/pound for farms that are 10 acres or larger. Smaller farms are profitable only when operated as a family venture.     

对虾养殖若干计算程序的研究

经多年潜心研究并汇集了对虾养殖中常用的２０多个计算式,并编好计算程序输入“对虾养殖计算器”,由原来记忆困难,操作麻烦变为计算器记忆,操作简单,可准确快速地解决养虾生产中常遇到的各种计算问题,成倍地提高工作效率。     

Protein Requirements of the Freshwater Prawn Macrobrachium rosenbergii Evaluated by the Factorial Method

The dietary protein requirement of the freshwater prawn Macrobrachium rosenbergii to obtain the maximum body protein retention was assessed by the estimated protein needed daily for maintenance (M) and body protein increment (G). The body protein increment was estimated by quantifying body nitrogen increments when the prawn was fed high‐protein diets composed primarily of casein. The protein required for maintenance was estimated by regressing weight gains in feeding experiments using graded dietary levels of casein. The true daily retention (R) or increase in body protein of the prawn corresponds to the sum of M and G. The values of M, G, and R determined in the present study were 3.86, 0.24, and 4.10 g/kg body weight/d, respectively. On the basis of the daily body protein increment and the net protein utilization of casein (58%), dietary protein requirement of the juvenile M. rosenbergii for maximum body protein retention was suggested to be about 7.1 g/kg body weight/d.     

Immunomodulatory effect of Cynodon dactylon against white tail disease of giant freshwater prawn,Macrobrachium rosenbergii (de Man, 1879)

The giant freshwater prawn, Macrobrachium rosenbergii, is an economically important and extensively cultured crustacean worldwide. The viral pathogens, Macrobrachium rosenbergii nodavirus (MrNV) and extra small virus (XSV) are responsible for causing severe mortalities in the hatchery and nursery phases. This study investigates the protection of postlarvae of freshwater against white tail disease (WTD) using plant extract derived from Cyanodon dactylon and the modulation of the prawn non‐specific immunity. To determine the immunomodulatory effect of C. dactylon extract, the prawn was injected with plant extract and various immunological parameters were estimated. The immunological parameters such as proPO, SOD, THC and clotting time were found to be significantly higher in the plant extract‐injected prawn when compared with control groups. The results of real time PCR analysis revealed up regulation on the expression proPO, SOD and lysozyme genes in MrNV and XSV challenged prawn postlarvae treated with C. dactylon extract. Infectivity experiment showed high relative per cent survival in MrNV and XSV‐challenged prawn postlarvae treated with C. dactylon extract. These results strongly indicate that the administration of C. dactylon plant extract enhances immunity of the prawn. Based on the results, this study recommends that the immersion of postlarvae in C. dactylon plant extract is a potential prophylactic agent against WTD.     

Economic feasibility of prawn Macrobrachium production in South Carolina,USA

Cost and returns were estimated for freshwater prawn Macrobrachium rosenbergii farming as a supplemental enterprise in South Carolina in relation to the following factors: (1) existing versus new investment for ponds and water supply; (2) three stocking strategies (postlarvae alone, a 50:50 mixture of postlarvae and nursed juveniles and nursed juveniles alone) at various densities (2·15–8·61 prawns m^?2); (3) a range of prices for seed stock ($0–50 per thousand); and (4) two marketing alternatives (sale of product as shrimp tails only or with the large animals marketed heads-on and the rest as tails). Net revenue estimates indicate that prawn aquaculture has potential to become a source of supplemental income to farmers in the coastal plain area of South Carolina and throughout much of the southeastern United States. This is especially likely if the enterprise can utilize existing pond facilities that are already discounted into the value of the land or were constructed during a period of lower investment costs. A prawn farm is unlikely to be profitable if postlarvae alone are stocked, even in existing facilities, but if a mixture of postlarvae and juveniles or juveniles alone are stocked in existing facilities, profitability is likely at seed costs up to about $40 per thousand.     

A Preliminary Evaluation of Naturally Occurring Organisms,Distillery By-Products,and Prepared Diets as Food for Juvenile Freshwater Prawn Macrobrachium rosenbergii

The relative acceptability and suitability of naturally occurring pond organisms identified as likely natural food items for juvenile freshwater prawn, Macrobrachiurn msenbergii, were evaluated under controlled conditions. The potential of direct consumption of materials used as organic pond fertilizer (distillers dried grains with solubles [DDGS] was also evaluated. Growth and survival of prawn fed gastropods, oligochaetes, zooplankton, or DDGS were compared with those fed a nutritionally-complete pellcted diet (control). Groups of five juvenile prawn (average weight 1.66 ± 0.10 g) were stocked into eighteen 7.5-L glass aquaria. Dietary treatments were evaluated in triplicate aquaria for 21 days. Prawn fed live zooplankton exhibited a significantly higher rate of weight gain (P < 0.05) than drawn in other treatments, as measured by differences in slopes of regression lines for weight gain over time. There were no significant differences (P > 0.05) in rates of gain for prawn fed a complete diet and those fed DDGS or gastropods. Prawn fed oligochaetes grew significantly slower (P < 0.05) than those fed the prepared diet. Results indicate that juvenile prawn as large or larger than 2g can utilize live zooplankton and that DDGS may be consumed directly by prawn. Thus, DDGS may serve a dual role as a feed and pond fertilizer. Additional research in pond management strategies that maximize zooplankton and gastropod numbers and the potential of DDGS as a combination food/fertilizer in freshwater prawn production ponds should be conducted.     

Current status and prospects of farming the giant river prawn Macrobrachium rosenbergii (De Man) in Bangladesh

Giant river prawn (Macrobrachium rosenbergii) farming plays an important role in the economy of Bangladesh. Presently, it is cultured in around 50 000 ha area with total annual production of 23 240 t. Traditional extensive prawn farming has been expanding over the last three decades through the introduction and adoption of improved culture systems, such as culture of prawn‐carps, prawn‐shrimp‐fish and prawn‐fish‐rice as concurrent and rotational systems. Efforts for the development of improved techniques on broodstock management, seed production and rearing and grow‐out of prawn have been made over the last decade. The outcomes are low‐cost feed for broodstock, production of post‐larvae in net cages (hapa), all‐male prawn culture, periphyton based prawn‐tilapia culture, C/N based prawn culture, organic prawn farming, prawn‐mola culture and prawn‐carp‐mola polyculture. Despite the development of culture technologies, a number of challenges for sustainable development of prawn farming need to be overcome to realize the potentials of this promising sector. Good aquaculture practises at all levels and application of measures for quality control and food safety would ensure sustainable development of prawn farming in Bangladesh.     

渤海对虾流网作业网列和网高最佳尺度研究

依据对虾流网捕捞原理，设计了与捕捞作业同步的试验和调查方法，就取得的资料归纳出与各级流网船相匹配的最佳网列长度和网片高度分别为：５９ｋＷ以上渔船网列长６０００ｍ，高９ｍ；２９ｋＷ渔船网列长４０００ｍ，高８ｍ；１５ｋＷ渔船网列长３０００ｍ，高７ｍ；９ｋＷ渔船网列长２０００ｍ，高７ｍ。这项研究成果为制定渤海对虾流网渔业管理细则提供了科学依据。     

Embryonic development of Ganga river prawn Macrobrachium gangeticum (Bate)

Macrobrachium gangeticum (Bate) are commercially valuable prawns that are broadly distributed in the Ganga river that flows from northern to eastern India. We studied embryonic development from cleavage (blastomeres), segmentation, formation of optic vesicle, eye pigment development to larva formation, as these data are largely unknown in this species. We conducted this study using mature M. gangeticum broodstock placed in freshwater tanks. Just after spawning, females were kept in separate aerated tanks, where fecundity was estimated from the total number of eggs. Thereafter, egg samples from berried females were used to study their embryonic stages. The correlation coefficient between size and prawn weight, egg weight, egg number, body weight and egg mass of different sizes of prawns was analysed. Our results show that an increase in prawn size led to an increase in egg weight and egg number while decreases in body weight:egg mass ratio was noticed. Further results indicate that an increase in prawn weight had a positive impact on egg weight and egg number. The embryo development stages were used in this study as a tool to evaluate the development process of the prawn in a hatchery environment.     

中国对虾越冬期褐斑病的组织病理观察

由患不同程度褐斑病对虾的组织病理切片观察发现,各时期的褐斑病都包括甲壳及壳下内部组织两部分的病变;都有增生性和非增生性两种组织应答。故推论是由多种病原菌混合污染所致。在早期褐斑病虾之甲壳表面发现有粘液状分泌物,说明此时在对虾甲壳表面已有了局部免疫反应。     

ANALYSIS OF THE COMMERCIAL-SCALE COST OF PRODUCING FRESHWATER PRAWN Macrobrachium rosenbergii IN THE SOUTH CENTRAL UNITED STATES

Freshwater prawn, Macrobrachium rosenbergii, production costs have mainly been estimated from experimental results or from limited numbers of producers. This paper discusses results from a cost of production survey sent to freshwater prawn producers in the south central United States in 2005. Feed and stocking costs were the highest variable costs and were related to the proximity of the input sources. Inorganic fertilizer cost was significantly greater for the south region while electrical costs were greater for the west region of the study area. The average prawn breakeven price covering all costs was $12.74, $14.27, $16.12, $17.18, and $14.55 per kilogram for producers in Kentucky, Mississippi, Tennessee, “Other States,” and for all respondents, respectively. Producers could decrease costs by improving yields, i.e., by increasing survival and/or weight gain, or by decreasing stocking, feed, and electrical costs; or by finding multiple uses of the equipment used to grow-out and harvest freshwater prawns.     

马氏沼虾的成虾形态及特征鉴别

马氏沼虾是我国从斯里兰卡新引进的淡水虾类，外观略呈纺锤形，虾体共分为20节，除尾节外，虾体的每一节各具l对附肢，雌虾和雄虾在第五步足基部分别具有“A”和“M”状突起。头胸甲的胃区、心区、触角区表面较粗糙，两侧还有数条与虾体平行的浅棕色斑纹。虾苗时期多数个体呈淡褐色，性成熟后体色呈浅褐、淡青偏褐色或淡灰色。额角尖端微微上翘向前伸展，但不超出第二触角的触角片末端，上翘高度不超过额角上缘鸡冠状隆起的顶端，齿式为7～13／4～6。其生物学特性与罗氏沼虾和日本沼虾相比有许多相似之处，但在体色、额角、头胸甲和腹甲侧片等形态特征上差异十分明显。本文描述了马氏沼虾的外部形态及结构，比较了上述几种虾的主要特征，并就“雄虾特化”现象以第二步足与体长之比作为依据提出了质疑。     

Rice fields to prawn farms: a blue revolution in southwest Bangladesh?

This paper examines freshwater prawn (Macrobrachium rosenbergii) farming in southwest Bangladesh where a large number of farmers have converted their rice fields to export oriented prawn farms, locally known as gher. The gher design potentially provides good opportunities for diversified production of prawn, fish, rice and dike crops, that has brought about a ‘blue revolution’. The average annual yield of prawn, fish and rice was estimated at 467, 986 and 2,257 kg ha⁻¹, respectively. Large farmers produced higher production due to more inputs, larger farm size and longer experience of prawn farming than others. All farmers in different gher size categories (i.e., small, medium and large) made a profit, with seed and feed dominating variable costs. Despite a higher production costs per hectare, the average annual net return was higher in large farms (US2,426), compared with medium (US2,426), compared with medium (US1,798) and small (US$1,420) farms. Prawn production in gher systems has been accompanied by a great deal of social and economic benefits. Most farmers associate the blue revolution with increases in income and living standards. Socio-economic benefits of the households of prawn farmers depend on resource ownership (i.e., farm size) and are very apparent. Nevertheless, a number of significant challenges, particularly social and environmental issues, are vital in translating its benefits effectively to the thousands of rural poor.     

The potential of mixed culture of genetically improved farmed tilapia (Oreochromis niloticus) and freshwater giant prawn (Macrobrachium rosenbergii) in periphyton-based systems

The production performance of genetically improved farmed tilapia (GIFT, Oreochromis niloticus) and freshwater prawn (Macrobrachium rosenbergii) in periphyton‐based systems were studied in farmers' ponds at Mymensingh, Bangladesh. Fifteen ponds (200–300 m² area and 1.0–1.5 m in depth) were used to compare five stocking ratios in triplicate: 100% GIFT, 75% GIFT plus 25% prawn, 50% GIFT plus 50% prawn, 25% GIFT plus 75% prawn and 100% prawn. Ponds were stocked at a total density of 20 000 GIFT and/or prawn ha^?1. Bamboo poles (mean diameter 6.2 cm and 5.5 pole m^?2) were posted in pond bottoms vertically as periphyton substrate. Periphyton biomass in terms of dry matter (DM), ash‐free DM and chlorophyll a were significantly higher in ponds stocked with prawn alone than in ponds with different combinations of GIFT and prawn. Survival of GIFT was significantly lower in ponds stocked with 100% GIFT (monoculture) whereas, that of prawn was significantly higher in its monoculture ponds indicating detrimental effects of GIFT on prawn's survival. Individual weight gains for both species were significantly higher in polyculture than in monoculture. The highest total fish and prawn yield (1623 kg GIFT and 30 kg prawn ha^?1) over 125–140 days culture period was recorded in ponds with 75% GIFT and 25% prawn followed by 100% GIFT alone (1549 kg ha^?1), 50% GIFT plus 50% prawn (1114 kg GIFT and 68 kg prawn ha^?1), 25% GIFT plus 75% prawn (574 kg GIFT and 129 kg prawn ha^?1) and 100% prawn alone (157 kg ha^?1). This combination also gave the highest economic return. Therefore, a stocking ratio of 75% GIFT plus 25% prawn at a total density of 20 000 ha^?1 appeared to be the best stocking ratio in terms of fish production as well as economics for a periphyton‐based polyculture system.