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1.
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.  相似文献   

2.
The marketing of organically labeled prawns is predominately in a cooked or raw frozen form to avoid the development of melanosis (black spot). Certification for organic status prohibits the use of any added chemicals. The application of 60% CO2/40%N2 modified atmosphere to chilled (raw) prawns using two species of prawn was investigated for the ability to control black spot formation. Sensory assessment and microbiological counts were used to determine the end of product shelf life. Modified atmosphere packaged (MAP) prawns exhibited no melanosis for up to 16 days. The high quality life was retained for 12 days; shelf life of 16 days, according to standard microbiological criteria, was achieved, which is more than twice previously reported for non-MAP prawns. Results suggest MAP may be an effective method for the marketing of organically grown prawns as well as those produced by conventional prawn aquaculture without application of the normal chemicals used to prevent black spot.  相似文献   

3.
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.  相似文献   

4.
Abstract

Prawns (Macrobrachium rosenbergii) were subjected to conditions, which simulated domestic and export handling practices. Prawns were mixed with crushed ice to maintain the prawn samples temperature at 0°C and were stored at room temperature (25 ±2°C) for 48 hr for the domestic handling trial, while for export handling, the samples were kept in a cold room at (0 ±1°C) for 72 hr. Both processes showed sensory, chemical and instrumental changes but the magnitude of the changes for domestic handling was greater than for those of the export trial. Maximum load (firmness), energy to the breaking point (chewiness) and percent of cooking loss increased as storage time increased up to 12 hr, after which prolonged storage resulted in a decrease in these parameters in the cooked samples. Expressible juice decreased during the first 12 hr, later increased gradually. Other chemical parameters such as the soluble-insoluble collagen ratio, proteolysis index (PI) and total volatile nitrogen (TVN) of cooked prawn increased with the increase in storage time. Good correlations among instrumental, chemical and sensory evaluation results were obtained for texture and taste-odor attributes of samples from both of the handling trials. Blanching and deheading of the prawns were found to maintain qualities very well, while samples, which underwent proper handling procedures, exhibited some quality changes after 48 hr.  相似文献   

5.
The effects of baking, boiling, microwaving, and frying on the proximate composition and fatty acid content of the edible portion of Indian white prawns (Fenneropenaeus indicus) were determined. Mean moisture, lipid, protein, and ash contents of raw prawns were 72.1, 4.32, 21.5, and 1.31%, respectively. For all cooking methods, moisture decreased and protein increased, while fatty acid compositions changed uniquely for each method. In fried prawns, the n3/n6 ratio was the lowest and significantly differed from the other treatments. The heat treatment significantly changed the proximate composition and fatty acid content. Baking and microwaving are the best methods of the four for cooking prawn while preserving their nutritional value, especially on the basis of recommended dietary intake of DHA and EPA.  相似文献   

6.
“太湖1号”杂交青虾规模化繁育技术研究   总被引：2，自引：0，他引：2  
利用53hm2标准化鱼池,采用雌雄亲虾同池的放养模式与集中投放抱卵虾孵化培育模式2种模式进行“太湖1号”杂交青虾的规模化繁殖试验。结果显示,本期共繁殖生产虾苗33533．86万尾,31878．33kg。雌雄亲虾同池培育的产苗量比集中投放抱卵青虾培育的产苗量要低36．49～69．26kg／hm2,或132．85万。143．607万尾／hm2,苗种规格大小差异大。雌雄亲虾同池培育的捕苗时间从7月18日到8月25日,共计38d,集中投放抱卵亲虾培育池的苗规格较一致,捕苗时间为期25d,捕捞时间缩短了13d。这表明,集中投放抱卵虾孵化培育模式可作为青虾规模化繁殖生产的优选方式。  相似文献   

7.
The prevailing notion in the prawn (Macrobrachium rosenbergii) culture industry is that the large male prawns that dominate the product value in research and commercial populations should, alone, be the target of commercial mono‐sex (all‐male) culture. However, studies have shown that the male prawn's response to increasing density (intensification) is controlled by a strong hierarchical dominance‐based social structure resulting in a large, disproportionate, increase in low value small animals in the ‘lower’ modal class of the male prawn size distribution. In contrast, prawn females and other aquatics, such as marine shrimp, display a moderate and uniform response to intensification in all size classes. Indeed, the densities in which prawn male superiority has been demonstrated are well below those used in intensive marine shrimp culture. This article: (1) discusses the background to the issue, (2) discusses the notion that because female prawns appear to be ‘marine shrimp‐like’ – with a normal size distribution indicating a lack of a strong social dominance – this will render them superior to all‐males under intensive growing conditions, (3) presents a ‘rate‐of‐response‐to‐density’ model projecting a female‐superior response to high previously untested densities, (4) summarizes results of a pond field test conducted at Auburn University (Auburn, AL, USA) to test the model's results whereby hand‐sexed prawns in treatment‐replicated in‐pond cages at densities of 10, 25, 40 and 55/m2 showed that all‐female prawns give higher production and product value than males under intensive conditions, (5) discusses the use of biotechnological methods to sex‐reverse brood‐stock to produce all‐females and (6) discusses the notion that the potential of genetic selection to increase prawn production is only possible using females.  相似文献   

8.
The effects of broodstock source (pond-reared and wildcaught from shallow waters) and prawn size (large—weight >120 g, and small-weight < 110 g) on ovarian maturation and reproductive success of Penueus monodon were evaluated. Large females underwent stage IV ovarian maturation and spawned with greater success than did small prawns. Both pond-reared and wildcaught females of the same size exhibited comparable maturation and spawning success. Large females rematured and spawned more frequently than small ones. Total eggs produced by large prawns was significantly greater than for small prawns; nevertheless, prawn source and size had no significant influence on amount of eggs spawned per spawning event. Egg quality varied greatly in terms of percent fertilization, hatch rate, and metamorphosis to first protozwa stage.  相似文献   

9.
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10.
The giant freshwater prawn Macrobrachium rosenbergii was first introduced into mainland China by the Chinese Academy of Agricultural Sciences from Japan in 1976. It was cultured at the Guangdong Province Fishery Institute (now as Pearl River Fishery Institute, Chinese Academy of Fishery Sciences). Following these early efforts, giant freshwater prawn culture has gradually spread to northern and inland areas. At this time (2011), China has become the largest producer of giant freshwater prawn in the world. Due to a preference of cooking with fresh aquatic products, Chinese retail markets have developed which have special live‐holding counters. From small rural shops to urban supermarkets and specialty restaurants, live seafoods are commonly available whereby customers pick out the products they wish to purchase and consume. Giant freshwater prawns are produced in over 35 countries throughout the world. They are usually sold either fresh, on‐ice, or frozen. What makes the Chinese prawn industry unique is its focus on a live transportation and marketing model. As a result, numerous innovative live‐transport technologies have been developed which have been key to the success of this expanding domestic industry. In this article, we would like to give a general overview of the giant freshwater prawn industry, its status in China, and the special role live‐transportation has for expanding production of giant freshwater prawns.  相似文献   

11.
Production and population characteristics of monosex male (all‐male) giant river prawns, Macrobrachium rosenbergii, were compared with a normal (mixed‐sex) population in separate studies in Mississippi and Kentucky (USA) under low and high density stocking conditions, respectively. In Study 1 (Mississippi), juvenile prawns were stocked into eight 0.05–0.06 ha ponds at 24,700/ha. The mean stocking weight of all‐male was 0.34 g and mixed‐sex was 0.39 g. Prawns were fed 23% crude protein “range cubes” and harvested after 120 d for the all‐male prawns and 112 d for mixed‐sex prawns. In Study 2 (Kentucky), juvenile prawns from each group were stocked into six 0.04 ha ponds at 60,000 juveniles per hectare. The mean stocking weight for all‐male was 0.38 g and for mixed‐sex juveniles was 0.34 g. Prawns were fed a commercial sinking pellet (33% protein) once daily at a standardized rate and harvested after 105 d. In both locations survival of mixed‐sex prawns and all‐male prawns was not significantly different and the final average weight of all‐male prawns was significantly greater than the average weight of mixed‐sex prawns. For the study in Kentucky, total production was not significantly different between treatments, whereas in Mississippi total production in the all‐male ponds was significantly higher than in the mixed‐sex ponds. For both studies, the production size index of all‐male prawns was significantly greater than that of mixed‐sex prawns. In terms of population structure, in all‐male ponds there was a significant increase in orange claw (OC) males compared with the mixed‐sex ponds both as a percent of sex and a percent of total population. The increase in OC numbers in all‐male populations may be due to a lack of females to stimulate the transition of males to the final, sexually mature, blue claw stage. As target weights increase from 20, 30, and 40 g, the all‐male populations were increasingly superior in terms of production (kg/ha) of those target sizes. The economic benefit of all‐male over mixed‐sex populations will be principally based on an examination of tradeoffs that primarily consider the cost difference of juveniles relative to the price differences for different final harvest weights.  相似文献   

12.
Freshwater prawn (Macrobrachium rosenbergii) culture in the Western Hemisphere is primarily, if not entirely, derived from 36 individual prawns originally introduced to Hawaii from Malaysia in 1965 and 1966. Little information is available regarding genetic variation within and among cultured prawn stocks worldwide. The goal of the current study was to characterize genetic diversity in various prawn populations with emphasis on those cultured in North America. Five microsatellite loci were screened to estimate genetic diversity in two wild (Myanmar and India‐wild) and seven cultured (Hawaii‐1, Hawaii‐2, India‐cultured, Israel, Kentucky, Mississippi and Texas) populations. Average allelic richness ranged from 3.96 (Israel) to 20.45 (Myanmar). Average expected heterozygosity ranged from 0.580 (Israel) to 0.935 (Myanmar). Many of the cultured populations exhibited reduced genetic diversity when compared with the Myanmar and the India‐cultured populations. Significant deficiency in heterozygotes was detected in the India‐cultured, Mississippi and Kentucky populations (overall Fis estimated of 0.053, 0.067 and 0.108 respectively) reflecting moderate levels of inbreeding. Overall estimate of fixation index (Fst = 0.1569) revealed moderately high levels of differentiation among the populations. Outcome of this study provide a baseline assessment of genetic diversity in some available strains that will be useful for the development of breeding programmes.  相似文献   

13.
Tanzania demarcated three prawn fishing zones along its coast to spread fishing pressure and help the prawn fishery to recover. However, it is unknown whether the demarcated zones correspond to the genetic stock structure of the world's most commercially important prawn, the giant tiger prawn (Penaeus monodon). Thus, this study used partial mitochondrial control region sequences (534 base pairs) to test the hypotheses that (1) giant tiger prawns in Tanzania's demarcated prawn fishing zones are a single stock and (2) the giant tiger prawns on the Tanzanian coast experienced a recent demographic expansion. The sequences showed high haplotype diversity (h = 0.998–1.0) and low nucleotide diversity (θπ = 1.89%–2.24%). The neutrality test and mismatch analysis showed that the hypothesis of recent demographic expansion could not be rejected. The analysis of molecular variance revealed low and insignificant fixation indices between the zones (FST = 0.00025, p > 0.05; ΦST = −0.00027, p > 0.05), suggesting that the three demarcated fishing zones constitute a single stock and that fishers may be targeting the same stock. Furthermore, it was discovered that Zone 2 has the potential to replenish depleted areas; thus, it should be prioritised in future conservation planning.  相似文献   

14.
This study was conducted to evaluate the effects of all‐male, mixed‐sex and all‐female freshwater prawn (Macrobrachium rosenbergii) in a polyculture with major carps (Catla catla and Labeo rohita) and self‐recruiting small fish molas (Amblypharyngodon mola) in the fallow rice fields of Bangladesh. There were three treatments with three replicates. All ponds were stocked with carps and molas plus either all‐male prawns (treatment MP), mixed‐sex prawns (MFP) or all‐female prawns (FP). Prawn, mola, catla and rohu were stocked 20 000, 20 000, 1750 and 750 ha?1, respectively, in all treatments. The prawns were fed twice daily, starting at 8% body weight and gradually reduced to 3% body weight. The fish were fed in the morning with mustard oil cake and rice bran (1:2 ratios) at 3% body weight. Significantly higher production of prawns (697 kg ha?1) was obtained in treatment MP, which yielded 34.7% and 56.2% more production than MFP and FP respectively. Significantly higher total production of 1620 kg ha?1 and a higher benefit–cost ratio of 2.10:1 were also obtained in treatment MP. It can be concluded that an all‐male prawn culture is economically more viable than all‐female and mixed‐sex prawn cultures, along with other fish like major carps and the nutrient‐dense molas in the polyculture.  相似文献   

15.
Thailand was second only to P.R.China in annual production of giant river prawn. This article briefly describes the seed production of giant river prawn technology in Thailand and notes that broodstock management has paid scant attention to genetic issues. There are, however, ongoing selective breeding programmes on giant river prawn aimed to improve growth and disease resistance. In the conventional culture technology, postlarvae are stocked at a high density and prawns are harvested partially. The cropping period is long and the practice has led to disease outbreaks and deteriorated pond bottoms that result in frequent detection of antibiotic residue. The improved culture technology involves manual sexing of the prawns at 3 months and restocking only the male prawns into new ponds at low density. The technique gives higher yield and reduces incidence of disease and thus the need for prophylactics. The constraints to giant river prawn culture business in Thailand include low yield and a limited export market. The article describes three ways to expand and sustain the business of giant river prawn farming in the country: development of more genetically improved strains; culture of all‐male stock, and new culture techniques.  相似文献   

16.
Freshwater prawns, particularly, the Giant Freshwater prawn Macrobrachium rosenbergii, are one of the most economically important farmed species in the world. Faced with increasing disease problems in penaeid shrimp culture, farmers turned to freshwater prawn farming. Freshwater prawns were considered relatively less susceptible to diseases. However, with intensification of culture and increased world trade of the farmed species, emerging diseases are beginning to constitute an increasingly serious health problem in freshwater prawn culture. This article is a review of the important diseases reported in freshwater prawns, with particular emphasis on the white tail disease of M. rosenbergii as it is the most important disease recorded to date and also the most well studied among the diseases of freshwater prawns. Steps to be taken for proper health management in the farming of this species is also touched upon.  相似文献   

17.
The present study analyzes the prawn marketing chain before and after the implementation of a Danish-funded project (GNAEP) in three coastal districts of greater Noakhali, southeast region of Bangladesh. The results reveal that, before GNAEP, there was a longer prawn marketing chain with a number of intermediaries who used to share a considerable amount of market margin. However, after implementation of GNAEP, the prawn marketing chain has become shorter with a significant reduction of intermediaries which facilitates direct selling of prawns to processing plants through local Community Based Organizations (CBOs). The present prawn marketing system in the regions is in favor of prawn farmers. Farmers have greater advantages because 1) CBOs provide reasonable market price and actual weight, 2) CBOs can bargain with processing plants as the former are aware of the latest international market prices through Marketing Information System 3) number of intermediaries is lowered and 4) transport and preservation costs are reduced. The displaced intermediaries, some of whom are powerful persons in the society, have again started to influence the prawn market in different ways. This fact has opened up another discussion on how the power structure is shifting in this region and how they are affecting prawn marketing.  相似文献   

18.
ABSTRACT

Recent developments in prawn production technologies (i.e., added substrate, increased stocking densities, size grading, and increased feed rates) have increased production rates from 900-1,000 kg/ha to over 2,500 kg/ha. While prawn can receive substantial nutritional benefit from natural foods at the lower biomass densities, at higher production rates prawn are likely to be more dependent on prepared diets. To ensure that maximum production is being achieved by these new production technologies, production rates must not be nutritionally constrained. This study was conducted to compare the current recommended technology of phase feeding of different quality feedstuffs to prawns of different sizes with the feeding of a high-quality penaeid diet throughout the production season. Two treatments were evaluated: Treatment 1 was phase feeding (current technology-control) where prawns were fed unpelleted distillers' grains with solubles (DDGS) for the first four weeks, then a 28%-protein prawn diet for weeks 5-12, and finally a 40%-protein penaeid diet for weeks 13-16. In Treatment 2, prawn were fed the 40%-protein penaeid diet throughout the entire production period. Feeding rates in both treatments were based upon a feeding table. Three 0.04 ha ponds were used for each treatment. All ponds were stocked at 59,280 juveniles/ha and were provided with artificial substrate in the form of a polyethylene “safety fence” oriented vertically to increase available surface area by 50%. After 106 culture days, no significant differences (P >0.05) were observed between treatments in terms of yield, average individual weight, food conversion ratio (FCR), or survival, which averaged 2,575 kg/ha, 46 g, 2.3, and 94%, respectively, overall. Due to the higher cost of the penaeid diet (US$0.84/kg), feeding costs for the penaeid diet treatment (Treatment 2) were 38% higher than those for Treatment 1. No benefit to using higher protein diets during the first 12 weeks of prawn pond production was observed.  相似文献   

19.
A technical and socio‐economic survey conducted in the Dong Thap province of Vietnam to assess the current status of river pen culture of giant freshwater prawn Macrobrachium rosenbergii (De Man) showed that pen culture, which has been developed and operated by farmers' indigenous knowledge, requires more study in order to optimize stocking density and to assess its environmental impacts. In this study, the prawn pens were of rectangular shape, with an average size of 209 m2. Prawns were stocked in June at an average density of 62 pieces m?2 and fed on farm‐made feed and were harvested 2–4 times starting from 4 months after stocking until late December or the following January. The average prawn yield was 0.52 kg m?2 year?1, ranging from 0.14 to 1.6 kg m?2 year?1. The average net return was US$0.71 m?2 year?1, ranging from US$1.24 to 4.37 m?2 year?1. About 73% of the farmers achieved positive net returns. The top five constraints for prawn pen culture were lack of knowledge of culture technologies, poor water quality, disease problems, poor quality of wild seed and lack of capital. Almost all farmers have no environmental awareness, and environmental regulations for prawn pen culture have not been established. Field measurements showed that all measured water quality parameters were within the range for good growth of giant freshwater prawns, and indicated that there was no significant accumulation of nutrients and organic matter at the bottoms of rivers or canals.  相似文献   

20.
This study was conducted to evaluate the consumer acceptability of post‐harvest freshwater prawns marinated in salt solutions (0.5%, 1%, 1.5% and 2% NaCl in the cooked product), and to compare the sensory acceptability of these treatments against prawns that had been salt acclimated pre‐harvest while still alive. The salt‐acclimated prawns were transferred to 250‐L tanks containing 10 ppt solar salt (NaCl with small concentrations of CaCl2 and KCl). Salts were increased by 5 ppt in 2 h increments until 30 ppt was reached. After 18 h of salt acclimation, prawns were chill killed. Prawns that were used for post‐mortem marination treatments were transferred to 250 L tanks with freshwater for 18 h prior to harvest and post‐mortem marination. Two consumer‐based sensory tests were conducted (n = 102). Results indicate that flavour, texture and overall acceptability of prawns increased (P < 0.05) as the salt concentration increased from 0.5% to 1.5% in marinated prawns. In addition, marinated prawns that contained 1% sodium chloride after cooking did not differ (P > 0.05) in acceptability when compared to salt acclimated prawns which contained 0.5% sodium chloride in the cooked product. The salt‐acclimated product was preferred (P < 0.05) over the 0.5% salt marination treatment, although they did not differ in final salt concentration. This indicates that salt acclimation enhanced product acceptability through increased salt concentration as well as due to the salt acclimation process, thus lowering the amount of sodium chloride that was necessary to enhance product acceptability.  相似文献   

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