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.     

SOCIOECONOMIC ASPECTS OF SMALL-SCALE FRESHWATER PRAWN MARKETING SYSTEMS IN MYMENSINGH,BANGLADESH

An investigation was carried out in Mymensingh region of Bangladesh to understand current practices of freshwater prawn (Macrobrachium rosenbergii) marketing systems. Prawn marketing is almost exclusively maintained by the private sector, where the livelihoods of a considerable number of people are associated with prawn distribution and marketing systems. The market chain from producers to consumers passes through a number of intermediaries. The prawn is a highly valued product in international markets; most of the prawns (60%) are therefore exported, particularly to the USA, Japan and Europe. The rest (40%) of the under-sized prawns are sold to local markets in Mymensingh. The price of prawn depends on quality, size and weight, and grade. In spite of marketing constraints, livelihood outcomes are positive and most of the households of traders (75%) have improved their social and economic conditions through prawn marketing activities. However, concerns arise about the long-term sustainability of prawn marketing due to poor road and transport facilities, inadequate supply of ice, lack of money and credit facilities, and poor market infrastructure. It is therefore necessary to provide institutional, organizational, and government support for a sustainable prawn market.     

CONSTRAINTS TO THE ADOPTION OF RICE-FISH FARMING BY SMALLHOLDERS IN BANGLADESH: A FARMING SYSTEMS ANALYSIS

In spite of its potential, the adoption of rice-fish farming among smallholders in Bangladesh is low. This paper seeks to explain this low adoption by evaluating the rice-fish technology as one element of the household farming system. The adoption of the technology is associated with a range of technical, human, and institutional constraints. Rice-fish technology is not structured to address the food security goal of smallholders and, therefore, is adopted by only those who are better placed to assume the risks. This paper concludes that the adoption of the technology among this group of smallholders would accelerate when policymakers acknowledge its constraints and structure extension services accordingly.     

SELLING FRESHWATER PRAWN IN FOOD FESTIVALS: A MARKETING EXPERIMENT IN KENTUCKY

This paper evaluated consumer perceptions of cooked freshwater prawn sold in festivals. Data were collected from prawn consumers attending the Kentucky State Fair and Garrett's Festival (in Lexington, Kentucky) on knowledge of prawn, seafood consumption frequency, proclivity of purchasing locally grown food, etc. A conjoint experiment was conducted in which respondents rated nine hypothetical plates of cooked prawn, differing from one another by the number of prawns, price, cooking style, and the presence or absence of side items. Results from data analyses indicated that the Garrett's Festival respondents were more educated and had more knowledge of prawns than the State Fair respondents. The State Fair respondents, while indifferent to the prawn cooking style, considered the product's price to be more important than the Garrett's Festival respondents. All results suggest that vendors would be more successful in dedicated prawn festivals than participating in festivals of general interest, such as the State Fair.     

对虾流网掉虾原因分析及其补救的技术措施

渤海、黄海北部秋汛捕捞对虾,以往主要使用拖网。为保护渔场水域的生态环境和幼鱼(幼体)资源,通过针对虾类行动的实验性观察,同时使用流网试捕。分析流网掉虾的原因和提出防范掉虾的技术措施,以便更好地实现“以流网代替拖网捕捞对虾”的技术改革。     

COMPARISON OF AQUACULTURE EXTENSION IMPACTS IN BANGLADESH

ABSTRACT

Production from small scale pond aquaculture in Bangladesh trebled in the decade to 1999 under the influence of extension projects of the Department of Fisheries. The impacts of completed aquaculture extension projects and practices of former participants have rarely been investigated so this was done for four past projects. The different extension approaches were: extension with credit and intensive or little supervision; demonstrations; group extension and informal extension by fry traders; and adaptive research-development. Generally extension recipients and non-participants had similar sized landholdings, but demonstration farmers had larger farms and ponds. Extension recipients mainly received information from project-related sources and rated its utility highly. Neighbours and control farmers mainly obtained information from mass media and other farmers, over 90% of these households also cultivated fish. Extension recipients generally followed better practices: for example stocking fewer fingerlings and achieving higher production than non-participants, but with wide variations. Training of fry traders appeared to reduce overstocking in general probably due to the advice of fry traders. Overall, 2–6 years after extension the recipients have continued to farm fish, have a fair understanding of good practice and achieve reasonable yields. Limited demonstration effects occurred. Extension through group approaches and informal agents seem to be cost effective for the many pond owners in Bangladesh.     

我国对虾养殖生产现状及展望

本文阐述了我国对虾养殖生产的基本情况及对虾养殖生产面临的潜在威胁。从科研,生产和销售三个方面提出了一些急待解决的问题和对策,并对我国养虾业发展的前途做了展望。     

对虾湿性颗粒饵料的研究

本文报道了对虾湿性颗粒饵料的配方、生产工艺及养殖效果。湿性颗粒饵料在适口性、引诱性、摄食率、蛋白的消化吸收率等方面都比干性颗粒饵料有所提高。摄食率提高5～15%,对蛋白质的消化吸收率提高10%以上,亩产增加10～20kg,饵料系数平均为1.9,下降0.10～0.23。虾个体平均体长增加0.6～1.0cm,亩经济效益增加285～538元。最后对研究结果进行了分析讨论。     

唐海县虾池赤潮生物种类与赤潮类型的研究

1989～1992年,我们对唐海县虾池赤潮生物种类与赤潮类型进行了研究。共发现赤潮生物21种,赤潮类型4种(单相型、双相型、三相型和四相型)。研究结果表明:发生在该县虾池中的绝大多数赤潮为多相型赤潮。     

虾池赤潮盛衰规律的研究

本文首次揭示了虾池赤潮在盛衰过程中池水溶氧、pH、PO_4—P 的变化特征及其与赤潮生物种类和数量的关系。研究表明,由中肋骨条藻和腰带光甲藻共同引起的虾池赤潮在全盛期的每日16:30左右可使池水中的溶氧量比未发生赤潮的虾池约高4mg/L,pH 值约高0.5;PO_4—P 含量于2:30左右达到最小值.8:30左右达到最大值。而水色的日变化则与赤潮生物的垂直移动有关。     

浅论对虾人工配合饵料

本文介绍了对虾人工配合饵料的发展概况,论述了对虾对各种营养成分的需求并简介了对虾配合饵料的添加剂和粘合剂。     

辽东湾中国对虾标志放流及其增殖效果的研究

本文根据辽东湾中国对虾标志放流实验与重捕资料，对辽东湾中国对虾放流场的选择、种苗的放流规格和放流增殖效果进行了研究。根据上述实验分析表明，在辽河口海区进行对虾放流增殖是较理想的场所，在秋汛生产期洄游分布遍及辽东湾传统的中心渔场；放流种苗的适宜体长规格为5cm以上，回捕率较高，最高达3．31％。这将对辽东湾生产性对虾放流提供科学的依据。     

Freshwater prawn farming in Bangladesh: history, present status and future prospects

Within the overall agro-based economy in Bangladesh, freshwater prawn ( Macrobrachium rosenbergii ) farming is currently one of the most important sectors of the national economy. During the last two decades, its development has attracted considerable attention for its export potential. Freshwater prawn farming offers diverse livelihood opportunities for a large number of rural poor. Although the prospects for prawn farming are positive, it requires some research and development activities for long-term sustainability. This paper provides an overview of freshwater prawn farming in Bangladesh.     

潮间带潜堤网栏养虾设施的设计

在近岸潮间带建设潜堤,并在堤顶设置拦网是一种新型的对虾人工养殖设施。这种潜堤网拦养殖设施,在涨潮时,海水越堤而过,注入池内;退潮时,利用拦网防逃,潜堤贮水,实现自行换水。该设施投资小,节省能源,管理方便,产量高。本文通过两个已建工程的设计,说明这种养殖设施的可行性,并提出潜堤和拦网设计中的各项参数的确定方法。     

POPULATION PROFILE DEVELOPMENT AND MORPHOTYPIC DIFFERENTIATION IN THE GIANT FRESHWATER PRAWN Macrobrachium rosenbergii (de Man)

Post-larval populations of Macrobrachium rosenbergii are characterized by a homogenous size distribution curve which changes, with time, to a positively skewed curve, with some individuals demonstrating a higher growth rate than the rest of the population. No morphotypic variation is observed at the post-larval and juvenile stages, and the ratio of males to females is 1:1, equally distributed along the whole size distribution curve. Both the mean weight and the development of the skewed distribution curve are inversely affected by increasing density. In a mature population, three male morphotypes can be clearly differentiated by claw color, relative size within the population and the ratio of claw length to body length. The Small Male (SM) morphotype is characterized by short clear claws, while the two larger morphotypes are characterized by Orange Claws (OC) and Blue Claws (BC). Their relative occurrence in the population is SM 20–25%, OC 15–25%, and BC 5–10%. No apparent morphotypic variation exists in females and their size distribution is generally homogenous. Increased population density does not change the relative position, nor the relative proportions of the three male morphotypes and the females, however, the degree of skewness of the curve is inversely related to the density.     

控制对虾弧菌病药物的实验研究

研究了一株对虾弧菌病病原菌对２４种药物的敏感性，测定了几种抗菌性较强、抗菌谱较广且价格较低廉的药物对该菌的最低抑菌浓度（ＭＩＣ）和最低杀菌浓度（ＭＢＣ）以及药物在海水环境中对该菌作用的有效性和药物联用效果。结果表明，不同药物具有不同的ＭＩＣ值，在特定的实验条件下，药物之间的作用表现为：协同、拮抗和无关三种结果，不同药物在不海水中作用时间不一。本文对药物滥施乱用的后果进行了讨论并提出了效控制病菌、合     

热休克法诱导日本沼虾四倍体的初步研究

以热休克抑制受精卵第一次卵裂，进行日本沼虾四倍体诱导实验，热休克温度在３８、３９、４０和４１℃，于产卵２１０￣２３０分钟后，处理１￣２分钟均可获得四倍体胚胎，４０℃处理１．５分钟，四倍体胚胎诱导率达３６．８％，３８和３９℃处理２分钟后所获得的嵌合体胚胎比率大于四倍胚胎比率，而热休克温度４０℃时，四倍体率显著高于合体比率，４１℃处理时由于有丝分裂异常导致胚胎死亡率高，更适宜的处理时间有待进一步研究，     

POLYCULTURE OF THE FRESHWATER PRAWN (Macrobrachium rosenbergii) WITH TWO COMBINATIONS OF CARPS IN MANURED PONDS

A study was conducted to 1) evaluate the compatibility of prawns (Macrobrachiurn rosenbergii) with carps, especially the effect of the common carp (Cyprinus carpio); and 2) measure the ability of prawns to utilize the foods available in manured systems. Carps used were the silver (Hypophthalmichthys molitrix), bighead (Aristichthys nobilis), grass (Ctenopharyngodon idella) and common carp (Cyprinus carpio). Four ponds (0.09 to 0.17 ha) were stocked with silver, bighead and grass carps while common carp were stocked in only two ponds. Total fish densities were 8,600/ha where four carps were stocked, but only 6,200/ha when common carp were omitted. Post-larval prawns (wt 0.116 g) were stocked at densities of 17/m². Swine (approximately 60/ha of pond surface area) were housed on pond dikes so that fresh manure continuously entered each pond. Two lots of swine were fattened during the experimental period and loadings of swine manure were calculated based on hog size and feed consumption. Growth periods were 163 days for fish and 107 and 121 days for separate stockings of prawns. Gains in biomass by prawns averaged 714 kg/ha in ponds without common carp and 364 kg/ha in ponds containing common carp. Gains in biomass for both fish and prawns were 3,619 kg/ha (19.8 kg/ha/day) in ponds with common carp and 2,924 kg/ha (18.0 kg/ha/day) in those without common carp. Prawn survival was higher (X = 84.5% vs X = 72.5%), but final average weight of prawns was lower (2.64 vs 5.86 g) in the presence of common carp due to competition for food between common carp and prawns. Competition from carp is believed to have exerted less influence on prawn survival than predation on small prawns by larger, faster-growing prawns.     

RESOURCE ALLOCATION EFFICIENCY OF THE PRAWN-CARP FARMERS OF BANGLADESH

This paper evaluates resource allocation efficiency of prawn-carp polyculture systems by making use of the data of 105 farmers of Bangladesh. Data Envelopment Analysis (DEA) was employed to estimate the efficiency. Mean technical efficiency (TE), allocative efficiency (AE) and cost efficiency (CE) were 85%, 58%, and 49%, respectively. Fifty percent of prawn-carp farmers displayed full TE whereas only 9% were cost efficient. Actual input application largely deviated from the technical and cost-efficient levels. TEs and AEs showed a positive and negative correlation with pond size, respectively. Labor, fingerlings and feed were overused while organic and inorganic fertilizers were underused in general. Adjustments in actual input allocations were necessary to make use consistent with TE and CE levels. The study concludes that mere achievement of technical efficiency in prawn-carp production may be a short-run concern; the farmers have to be economically efficient in the long-run.     

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.