Effects of Integrated Shrimp Farming in Vietnam

Despite being a leading shrimp exporter in the world market, shrimp farming in Vietnam is carried out by many small‐scale farmers who face constraints in complying with increasingly stringent food safety and sustainability standards. The best way for such small farmers to circumvent this paradox is to make effective integrations both horizontally and vertically. Using value chain and institutional economics approaches, this study determines the factors that influence the probability of horizontal and vertical integrations between the production and processing stages in the shrimp industry in Vietnam. Analysis results confirm that integrated shrimp aquaculture is much more effective than the traditionally small‐scale‐ and individual‐production mode. In addition, logit estimation results identify the key factors affecting integration, including effectiveness of the legal framework, production scale, infrastructure development, and farmers' skill and awareness. Several policy recommendations proposed to encourage the development of integration in shrimp farming in Vietnam could also be useful for other similar developing countries.     

Aquaculture and poverty alleviation in Ben Tre Province,Vietnam

Research results on the effects of aquaculture on poverty alleviation have been mixed. We use Tobit, simulation models and cross sectional survey data of 285 households, in Ben Tre Province, Vietnam, to evaluate the effects of aquaculture involvement on poverty, measured using per capita consumption of less than $1.25 USD, $1.50, and $2.00 per day. The results show for per capita consumption of less than $1.25 per day that households’ aquaculture participation or productivity had no or little effect on the living standard. For income levels above $1.25 per capita per day aquaculture participation or productivity influenced the standard of living.     

Production Methods and Resource Use at Litopenaeus vannamei and Penaeus monodon Farms in India Compared with Previous Findings from Thailand and Vietnam

Shrimp farms in India had average yields (pond surface basis) of 7.86 ± 1.04 (SE) m.t./ha/yr for Litopenaeus vannamei (n = 89) and 3.88 m.t./ha/yr for Penaeus monodon (n = 11). Average feed conversion ratio was 1.48 ± 0.04 for L. vannamei and 1.24 ± 0.12 for P. monodon. Land use for production ponds, supporting area, and feed ingredients averaged 0.634 ± 0.053 ha/m.t. for L. vannamei and 0.716 ± 0.087 ha/m.t. for P. monodon. Saline water volume used at farms without water exchange was 18,522 ± 4065 m³/m.t. for L. vannamei and 9528 m³/m.t. for P. monodon. Farms exchanging water used 149,188 m³/m.t. for L. vannamei and 191,500 m³/m.t. for P. monodon. Freshwater embodied in feed was 1678 ± 508 m³/m.t. for L. vannamei and 1401 ± 137 m³/m.t. for P. monodon. Average energy use for farm construction and repair, farm operations, and embodied in feed and liming materials was 82.14 ± 9.08 GJ/m.t. for L. vannamei and 59.03 ± 24.92 GJ/m.t. for P. monodon. Wildfish used to make fishmeal included in feed was 1209 kg/m.t. for L. vannamei and 1611 kg/m.t. for P. monodon. Farm infrastructure, pond management methods, yields, and resource use in India were similar to those previously reported for shrimp farms in Thailand and Vietnam.     

Water quality and plankton densities in mixed shrimp-mangrove forestry farming systems in Vietnam

Water quality and plankton densities were monitored in shrimp ponds at 12 mixed shrimp‐mangrove forestry farms in Ca Mau province, southern Vietnam, to detail basic water chemistry and assess whether conditions are suitable for shrimp culture. In general, water quality was not optimal for shrimp culture. In particular, ponds were shallow (mean ± 1SE, 50.5 ± 2.8 cm), acidic (pH < 6.5), had high suspended solids (0.3 ± 0.03 g l^?1), low chlorophyll a/phytoplankton concentrations (0.2 ± 0.05 µg l^?1 and 8600 ± 800 cells l^?1 respectively) and low dissolved oxygen (DO) levels (3.7 ± 0.15 mg l^?1). Eight out of the 12 farms sampled had potentially acid sulphate soils (pH < 4.2). Salinity, DO and pH were highly variable over short time‐periods (hours); DO in particular was reduced to potentially lethal levels (1–2 mg l^?1). Seasonal variations in water chemistry and plankton communities (i.e. salinity, DO, phosphate, temperature, phytoplankton and zooplankton densities) appear to be driven by differences in rainfall patterns. The presence or absence of mangroves on internal pond levees (‘mixed’ versus ‘separate’ farms) and the source of pond water (rivers versus canals) were of lesser importance in determining water quality patterns and plankton biomass. Zooplankton and macrobenthos densities were sufficient to support the current (low) stocking densities of shrimp. However, natural food sources are not adequate to support increases in production by stocking hatchery reared post larvae. Increasing productivity by fertilization and/or supplemental feeding has the potential for adverse water quality and would require improvements to water management practices. Some practical strategies for improving water quality and plankton densities are outlined.     

江苏省海涂养殖现状及可持续发展研究

根据江苏省海涂养殖的现状及目前海涂养殖生产中存在的主要问题,提出了今后江苏省海涂养殖可持续发展相应的对策.     

3种微藻对海水集约化对虾养殖尾水氮磷的去除效果

基于对虾生物絮团集约化养殖尾水含有高浓度硝态氮和磷酸盐的特征,比较分析钝顶螺旋藻（Spirulina platensis）、牟氏角毛藻（Chaetoceros muelleri）、盐藻（Dunaliella sp.）3种微藻在配制尾水中的存活生长状况及其对无机氮磷的去除效果,以期筛选出适宜的微藻用于后续尾水净化技术。采用显微镜计数法测定藻细胞密度,国标法测定总无机氮、氨氮、硝态氮、亚硝态氮和磷酸盐的含量。结果显示,钝顶螺旋藻在实验前后的藻细胞密度变化不大（P>0.05）,约为3.32×106 个/mL和5.88×106 个/mL;牟氏角毛藻和盐藻细胞密度有明显增加（P<0.05）,分别从初始的4.00×104 个/mL和2.50×105 个/mL升高至实验结束时的1.66×106 个/mL和1.06×107 个/mL。经过16 d实验,钝顶螺旋藻组对硝态氮和总无机氮去除率分别为79.60%和46.06%,显著高于其他各组（P<0.05）,第8天时对磷酸盐的去除率可高达98.55%;牟氏角毛藻组16 d的磷酸盐去除率为98.25%,显著高于其他各组（P<0.05）。研究表明,3种微藻均可在对虾养殖尾水环境中存活,且对尾水氮磷具有较好的净化效果。     

虾类遗传育种研究进展

虾在水产养殖业中占有极为重要的地位。20世纪50年代以来,随着众多经济虾类人工培育苗种的成功,其养殖业发展迅猛,由50年代的世界虾产量不足5.0×105t,到现在维持在1.9×106t的水平。尤其是近年来特种水产养殖业的兴起,使虾类的身价倍增。世界养殖业总产量约3—5年翻一番。90年     

Impact of yellow head virus outbreaks in the whiteleg shrimp,Penaeus vannamei (Boone), in Thailand

Yellow head virus (YHV) is known as a major pathogen in the black tiger shrimp, Penaeus (Penaeus) monodon. It can also cause serious mortality in farmed whiteleg shrimp, Penaeus (Litopenaeus) vannamei. However, there is no published information on the economic and/or production impact of the disease in P. vannamei. Shrimp with gross signs of YHV disease (faded body colour and 60–70% mortality) were observed in 20 study farms rearing P. vannamei in the central part of Thailand from the end of 2007 through early 2008. The estimated economic loss for these farms according to the Thai Animal Aquaculture Association was approximately US$3 million. Detailed sequence analysis of RT‐PCR amplicons from shrimp in all the study ponds revealed the presence of YHV Type 1b (YHV‐1b) alone (characterized by a 162‐bp deletion in the ORF3 region encoding the structural gene for gp116) and the absence of YHV Type 1a (YHV‐1a), the original YHV type reported from Thailand. Despite the large 162‐bp deletion (= 54 deduced amino acids) in the gp116 structural gene, histopathology of YHV‐1b infections was identical to that of YHV‐1a infections, and electron microscopy revealed that YHV‐1b virions were morphologically indistinguishable from those previously reported for YHV‐1a. In addition, an existing commercial RT‐PCR detection kit and an immunochromatographic test strip for the detection of YHV were proven to have been valid tests for both YHV‐1b and YHV‐1a. The source of the virus for these outbreaks was unlikely to have been the post‐larvae used to stock the ponds, as they were derived from domesticated specific pathogen‐free stocks free of YHV. Thus, it is possible that they originated from an unknown, natural reservoir.     

Resource Use Assessment of Shrimp,Litopenaeus vannamei and Penaeus monodon,Production in Thailand and Vietnam

Resource use was investigated at 34 Litopenaeus vannamei and five Penaeus monodon farms in Thailand and 30 L. vannamei and 24 P. monodon farms in Vietnam. Farms varied in water surface areas for production, reservoirs, canals, and settling basins; in pond size and depth; and in water management, stocking density, feeding rate, amendment input, aeration rate, crop duration, and crops per year. Production of L. vannamei averaged 17.3 and 10.9 m.t./ha/yr, and feed conversion ratio averaged 1.49 and 1.33 in Thailand and Vietnam, respectively. On average, production of 1 m.t. of L. vannamei required 0.58 ha land, 5,400 m³ water, 60 GJ energy, and 1218 kg wildfish in Thailand and 1.76 ha land, 15,100 m³ water, 33.7 GJ energy, and 1264 kg wildfish in Vietnam. Resource use per metric ton of shrimp declined with greater production intensity. In Thailand, P. monodon was produced at 0.2–0.4 m.t./ha/yr, with no inputs but water and postlarvae. In Vietnam, P. monodon production averaged 3.60 m.t./ha/yr. Production of 1 m.t. of P. monodon required 0.80 ha land, 36,000 m³ water, 47.8 GJ energy, and 1180 kg wildfish, and resource use per ton production declined with increasing production intensity.     

福建省霞浦县大弹涂鱼养殖可持续发展策略

福建省霞浦县大弹涂鱼养殖发展迅速，已成为该县的一项特色产业，目前全县大弹涂鱼养殖面积已突破1333ha，并取得了明显的经济效益。然而，随着大弹涂鱼养殖业的发展，也出现了一些需要解决的问题，本文就如何使霞浦县大弹涂鱼养殖能够保持可持续发展提出一些看法。     

Astaxanthin and Its Esters in Pigmented Oil from Fermented Shrimp By-Products

ABSTRACT

This study focuses on the isolation and quantification of astaxanthin and its esters in the oils extracted from shrimp waste. The content of astaxanthin was determined by high performance liquid chromatography and ranged from 1.5 to 2.1 mg g^?1. The astaxanthin and its esters were isolated by thin layer chromatography in three fractions: free astaxanthin, monoester, and diester of astaxanthin, with percentages of 44, 32, and 26%, respectively. Oleic acid was the major fatty acid in the monoester fraction, while palmitic, oleic, and stearic acids were present predominantly in the diester fraction. Free radical-scavenging activity of the oils and the three fractions was evaluated. All oils showed an effect on the decrease in the absorbtion of 1,1-diphenyl-2-picrylhydrazyl solutions, while among the fractions no significant difference occurred. Pigmented oil from shrimp waste is an organic source of pigment and antioxidant astaxanthin, the esters, and fatty acids, such as eicosapentaenoic and docosahexaenoic.     

Fishers,dams, and the potential survival of the world's rarest turtle,Rafetus swinhoei,in two river basins in northern Vietnam

1. Next to cetaceans and megafishes, freshwater turtles are the most iconic endangered freshwater species.
2. A detailed questionnaire survey conducted with more than 100 individuals from fishing communities in northern Vietnam was used to investigate the current status of Southeast Asian turtles and provides new hope concerning the survival of Rafetus swinhoei, for which recent official records in the wild are limited to a single individual in Vietnam.
3. The survey included the entire Vietnamese portion of the Da River in Hoa Binh and Son La provinces, as well as the Chu and Ma river system in Thanh Hoa Province, as they are the last sites where the world's rarest and largest Asian softshell turtle has been seen. The questionnaire, conducted in Vietnamese, focused on demographic details, fishing intensity and gear, the status of fishing grounds, and the frequency of interaction with turtles.
4. The great majority of fishers could recognize different turtle species from photographs and describe their preferential breeding habitats; not all knew that they are protected. A few confirmed that more than once each year they still encounter freshwater turtles during their fishing activities.
5. This survey provides detailed information on sites where freshwater turtles are still seen in northern Vietnam and broadens our hope that wild individuals of the extremely rare R. swinhoei may still be present in the remaining riparian wetlands of these biodiverse, dammed, and controlled river basins in North Vietnam.

     

Shrimp farming in Latin America: Current status,opportunities, challenges and strategies for sustainable development

Abstract

Shrimp farming in Latin America and the Caribbean (hereinafter, LA&C) is a complex, diverse and dynamic activity, occurring in 22 out of 36 countries, producing 231,000 tons, valued at US$ 1.2 billion in 2002¹. Farmed shrimp represents 52% of all shrimp volumes produced regionally, and almost 18% of all shrimp and prawn (S&P, hereinafter) cultivated worldwide. Whiteleg shrimp (Litopenaeus vannamei) constitutes 91% of all shrimp farmed in LA&C and five nations, led by Brazil ‐formerly by Ecuador‐, comprise 82% of farmed production. Over 90% of LA&C shrimp production is exported (230,000 tons of end products from both aquaculture and wild origin valued at US$ 1.36 billion), generating a trade surplus of US$ 1.28 billion (2002).

Farmed shrimp could easily surpass 513,000 tons by 2030, more than doubling current regional figures (2.9% annual growth rate, compounded). However, competition with Asian countries, anti‐dumping accusations and other factors might limit the expansion process, which is increasingly determined by strategically important matters rather than by physical production constraints. Here, a ‘production‐driven’ process of past decades is being replaced by a ‘demand‐led’ situation, where market and marketing issues will increasingly influence the outcome of shrimp farming.

Growing market competition will continue to press prices down and industry will be forced into a permanent process to improve competitiveness. Here, development strategies include actions by governments and producer associations, promotional and marketing campaigns and the application of good management practices across the production and distribution chains.     

Comparing Profits from Shrimp Aquaculture with and without Green-Water Technology in the Philippines

To reduce disease impact, Philippine farmers developed the green-water (GW) system, which has been spreading rapidly since 2008. In the most applied GW-system, the shrimp pond receives water from a reservoir stocked with tilapia. We collected financial data on GW and non-GW systems from farms having similar management and environmental context. All farms had more than one pond; the average pond area was < 1 ha, and total pond areas per farm ranged from 1.4 to 139 ha. The total variable and fixed costs per ha of shrimp pond were not different for GW and non-GW farms, but on GW farms the cost per kg of shrimp produced was lower. The latter was higher than the 2009 market price of 30 g shrimp for non-GW farms mainly. In GW farms the cost of seed was lower, and survival rates and individual shrimp weights at harvest were higher for an equally long culture period.     

Intensification of Shrimp Culture in Earthen Ponds in South Carolina: Progress and Prospects

Experiments on the intensive cultivation of Pacific white shrimp, Penueus vunnumei, in ponds in South Carolina were begun in 1985 at the Waddell Mariculture Center. A preliminary study involved two 0.1 ha ponds stocked at an average of 43 postlarvae/m², with management practices based on those used in Taiwan for intensive pond culture of Penueus monodon. Harvest yields averaged 6,757 kg/ha for one crop, demonstrating the technical feasibility of such intensive culture of P. vannumei. In 1986, 2.5 ha of ponds at the Waddell Center (six ponds totaling 2.0 ha at 40 postlarvae/m² and two totaling 0.5 ha at 60/m²) yielded a total of 13,606 kg (5,442 ke/hn). These results were obtained even though aeration and water exchange rates were substanthlly reduced and South Carolina experienced its worst heat wave and drought. This served as a pilot-sde, proof-ofconcept test. Tank studies in 1985 and 1986 showed little effect of stocking density on shrimp growth rate at densities of 20–100 animals/m². This was confirmed in ponds in 1987 when no differences in growth rates were observed at densities of 20–100 postlarvae/m². Harvest biomass increased directly with stocking density in all trials, reaching a maximum of 12,680 kg/ha/crop at 100 shrimp/m² in 1987. Initial attempts to intensify production in the nascent South Carolina shrimp farming industry occurred in 1986, when approximately 32 ha of private ponds were stocked at densities of 10–32 postlarvae/m². Farm harvests increased with stocking density, with maximum yield of 3,656 kg/ ha/crop. This trend toward intensification in the private sector is continuing, and in 1987 maximum harvests from private ponds were 5,050 kg/ha from a 0.3 ha pond and 4,625 kg/ha from a 1.5 ha pond. Prospects for further implementation of intensive culture in the private sector appear excellent, with yields of ≥ 10,000 kg/ha/crop expected from private farms within the next few years.     

Development of Dry Artificial Fish Bait for Trap Fishing Using Tuna Red Meat and Shrimp Head Wastes

ABSTRACT

This study developed and evaluated dry artificial fish bait for trap fishing utilizing tuna red meat (TRM) and shrimp head powder (SHP), aiming to replace the usage of edible fishes, such as sardines and squids, as bait. A total of 23 dry baits were prepared and tested for stability in seawater and acceptance by tilapia. Based on the stability and acceptability test results, two baits were selected as ideal and were further tested for protein leaching and dry matter loss in seawater. The tests revealed that the stick-shaped bait containing 61% TRM and 15% SHP was the ideal bait, with a protein leaching rate of 24.82 mg/g/h and dry matter loss of 36.6 mg/g/h. The catch rate of the traps baited with the artificial fish bait was significantly higher (P < 0.05) than those baited with squid meat (17 Nos/trap) and sardines (23 Nos/trap). Further, the catch rate of traps baited with artificial bait (38 Nos/trap) was found to be comparable with those baited with raw shrimp head wastes (SHW) (40 Nos/trap). When the bait was concentrated with 0.1% sodium benzoate, shelf life was extended by up to 6 months.     

南美白对虾绿色养殖试验报告

本文报告了在不使用任何药物的基础上,采用环保型的“福寿牌”饲料、生物过滤池,有益微生物EM和PsB及科学的日常管理,南美白对虾经过75d的养殖,平均体长达10．3cm,平均体重达10．2G,每平方米水面平均产量0．668kg,饲料系数为0．9,投入产出比为1．253。     

TCBS培养基在虾病防治监测中的应用

TCBS培养基是医学临床上分离致病弧菌的常用方法,而在对虾养殖生产中,也可以顺利达到分离弧菌的目的。对虾养殖池水质监测中,如果水中弧菌菌群数量在TCBS培养基上大量增加,由100个/ml以上,突然增加到300～500个/ml时,养殖池水也一定会发生很大的变化。当弧菌在水中形成优势种群,在虾体内达到致病量的时间约需1～2周。