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1.
This case study looks at changing livelihood strategies of the coastal population in Soc Trang Province in the Mekong Delta, Vietnam, and their impacts on natural resources. It provides an opportunity not only to document the impact of shrimp farming on coastal livelihood but also to better understand the link between brackish water aquaculture development and natural resource use. The approach includes a socio‐economic survey in six villages of the province focusing on risk strategies and livelihood diversification. Shrimp farming was found to be less risky and more profitable for households and private companies with a higher investment capacity than for poorer households. Households facing a high risk in shrimp farming diversified their aquaculture production, with other high‐value species like mud crab and elongated goby as a coping mechanism. The use of natural resources' collection is shifting from home consumption towards market‐oriented sales of juvenile mud crabs, clams or fish (elongated goby) to supply seed for brackish water aquaculture developments.  相似文献   

2.
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.  相似文献   

3.
    
In Mexico shrimp farming is the most important aquaculture activity. However, its sustainable development has been threatened in recent years by the economic risk associated with low yields caused by outbreaks of viral diseases. A stochastic bioeconomic model was developed to analyze the economics of farm management adjustments as a response to disease risks, using pond-level data from a farm operating in the State of Sinaloa, Mexico, during the period 2001–2005. The data base analyzed included different combinations of stocking density (in the range 6–30 PL/m2) and culture time (from 12 to 31 weeks), which allows for wider application of the simulation results, even at the industry level. Results from this study indicate that operating costs would increase by 33% if the farmer would choose to market product directly. Scenarios with lower stocking densities and intermediate culture times generated the highest probabilities 6–9 PL/m2 16–19 weeks (76%/100%/70%), and 10–14 PL/m2 20–24 weeks (72%/99%) of achieving superior economic performance, as demonstrated by achieving the target reference point of 35% operating profit margin ratio. The study reinforces the value of the current trends in Sinaloa to reduce stocking density as a good management practice to decrease the impact of diseases. This study also provides important additional knowledge on the specific economic results and risks associated with the combination of these two management variables at different levels.  相似文献   

4.
    
We estimated the impact on economic risk associated with the prevalence of white spot disease in shrimp farms in the State of Sinaloa, Mexico. Farms located in the jurisdiction of Local Aquaculture Health Boards (LAHBs) were used for preparing estimates during 2008–2010. Probability distributions of economic losses were calculated by comparing net revenues obtained under normal operations and operations affected by the disease, using Monte Carlo simulation, to estimate the impact of prevalence on losses in absolute and relative terms, probability of losing and loss per unit risk at USD$484.27/ha, 28.9%, 72.9% and 0.20. Regression analysis allowed estimating that, by an increases of 1% in prevalence, there were increases in the estimators of risk of USD$11.49/ha, 0.96%, 0.47% and 0.005. Correlation analysis showed that there were significant differences in prevalence among LAHBs districts and years. The higher prevalence coincided with the districts and years that exhibited higher risk. The source of water and use of nursery systems were the main differences in operating conditions among the districts, possibly determining to a large extent the differences in economic risk calculated for the districts. Sensitivity analysis indicated that prevalence was the main factor determining risk. A significant inverse relationship was found between shrimp prices and prevalence, as a consequence of speculative market conditions. The possibility of using this relationship for syndromic surveillance is considered. We propose the use of the estimators employed in this study for assessment of economic risk associated with white spot disease (and possibly others) and standardization of results for future research.  相似文献   

5.
    
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.  相似文献   

6.
对虾工厂化养殖的系统结构   总被引：9，自引：0，他引：9  
对虾工厂化养殖是在人工控制条件下,利用有限水体进行对虾高密度养殖的一种生产方式,它依托一定的养殖工程和水处理设施作为技术支撑,融合无公害生产的管理模式,是一种高效的环境友好型养殖。文章就构建对虾工厂化养殖平台中的各系统环节及该种生产模式的概况作系统综述。  相似文献   

7.
Site selection for aquaculture planning is a complex task involving the identification of areas that are economically, socially and environmentally suitable, available to aquaculture and commercially practicable. This paper reports upon a study into the use of a geographic information system (GIS) to assist in aquaculture planning. Using a case study in the site selection for land‐based shrimp farming within the Australian coastal zone, we demonstrate that a GIS has potential to assist aquaculture planning. Our analysis is based on a sequential, two‐stage approach. The first stage eliminates the grossly unsuitable portion of the study area through a preselection with low resolution, cheap and easily available data. The second stage then focuses on and ranks the remaining area using high resolution, possibly more expensive data. Finally, we use the GIS to present the results of the analysis in an easily accessible form.  相似文献   

8.
    
Abstract

The environmental costs associated with coastal aquaculture, though poorly understood, can in some cases be quite large. The presence of risk, uncertainty and insufficient monitoring can greatly reduce the power of traditional economic instruments such as environmental taxes and tradable permit systems to internalize these costs. Using the Texas shrimp farming industry as a specific example, this article explores the potential of environmental assurance bonds (EABs) as an alternative economic instrument to internalize environmental costs of aquaculture production under such conditions. Drawing from previous literature, an explicit distinction is made between two mechanisms simultaneously incorporated in the EAB: a deposit‐refund incentive and social insurance. The article discusses the role of each of these mechanisms in shifting the environmental costs of production back to firm. Practical application of EABs in the Texas coastal shrimp farming industry is then examined.  相似文献   

9.
    
The importance of moulting for growth in farmed shrimp is reviewed in relation to the physiological cycle, induction triggers, behavioural and compositional changes, elements for successful moulting and potential strategies for moulting management. Successful ecdysis is also dependent on pond water quality, health and nutritional status. The stages in the moulting cycle are as follows: premoult, the preparation period for moulting that comprises the longest period in the cycle and includes accumulation of nutrient reserves; post‐moult, short and crucial stage for shrimp recovery after moulting; and intermoult, when feeding is continuous and most of growth occurs. The ecdysis is very rapid and mainly dependent on suitable physiological status of individuals. Up to 10% of the whole shrimp moulting cycle may rely on body nutrient reserves, once feeding is decreased or ceased (premoult and post‐moult). Moulting is started by hormonal increments in haemolymph, 20‐hydroxyecdysone and methyl farnesoate, which are found similar in insects. Beyond health and nutrition, proper environmental conditions such as good water quality are essential for successful moulting, hardening of exoskeleton and rapid growth. Moulting prediction and management may result in significant feed savings in pond farming and potential effects of, for example, moon phases and stressors have to be further considered. The complex nature of moulting in shrimp, including different sorts of endocrine regulation and environmental stimuli, suggests it is difficult to be precisely controlled in farmed populations. Moulting physiology of shrimp is discussed in relation to some farming practices.  相似文献   

10.
    
There is growing interest in sustainable intensification of aquaculture production. Yet little economic analysis has been done on farm‐level effects of the economic sustainability of production intensification. Data from 83 shrimp farms (43 in Vietnam and 40 in Thailand) were used to identify (through principal component and cluster analyses) 13 clusters of management practices that reflected various scales of production intensity that ranged from 0–1999 kg/ha/crop to 10,000 kg/ha/crop and above, for both Penaeus monodon and Litopenaeus vannamei in Vietnam and Thailand. The clusters identified reflected sets of management practices that resulted in differing yields despite similarities in stocking densities among some clusters. The enterprise budget analysis developed showed that the more intensively managed clusters outperformed the less intensively managed clusters in economic terms. More intensively managed farm clusters had lower costs per metric ton of shrimp produced and were more profitable. The greater yields of shrimp produced per hectare of land and water resources in more intensively managed shrimp farms spread annual fixed costs across a greater volume of shrimp produced and reduced the cost per metric ton of shrimp. Costs per metric ton of shrimp produced decreased from the lowest to the highest intensity level (from US$10,245 at lowest intensity to US$3484 at highest for P. monodon and from US$24,301 to US$5387 for L. vannamei in Vietnam and from US$8184 at the lowest intensity level to US$3817 at the highest intensity level per metric ton for L. vannamei in Thailand). Costs of pond amendments used in shrimp production were particularly high in Vietnam and largely unwarranted, whereas fixed costs associated with the value of land, production facilities, equipment, and labor were sufficiently high in Thailand so that net returns were negative in the long run. Nevertheless, economic losses in Thailand were less at greater levels of intensification. The study demonstrated a clear value proposition for shrimp farmers to use natural resources (such as land) and other inputs in an efficient manner and supports findings from corresponding research on farm‐level natural resource use efficiency. Additional research that incorporates economic analysis into on‐farm studies of sustainable intensification of aquaculture is needed to provide ongoing guidance related to sustainable management practices for aquaculture.  相似文献   

11.
设计一套虾池自动投饲装置,初步解决了虾池自动投饲问题。提出非接触定位、测距定位和接触定位三种投饲装置自动沿岸行驶方案,并对不同方案的优缺点进行了分析比较;对机械执行系统进行了详细的结构设计,该系统包含拉线和投饲装置两部分,拉线约束投饲装置自动沿岸行驶,投饲装置完成投料动作;采用应变式重量传感器和微控制器等,开发出投饲装置的控制系统,实现定时定量的投料控制。同时,采用新兴的ZigBee无线网络通信技术,实现对投饲装置的虾料重量和蓄电池电压的远程监控。投喂实验表明,该系统的工作过程稳定、可靠。  相似文献   

12.
    
Abstract

Extensive forms of shrimp aquaculture have become an important source of income for farm households in the brackish water region of the Mekong Delta, Vietnam. The economic and production characteristics of farms are discussed in this paper, based on a 1997 farm survey, with particular emphasis on shrimp farming practices. Two types of shrimp fanning practice were observed, one based on natural recruitment of seedstock with few supplementary inputs, and the other based on relatively high cash investments in Penaeus monodon seedstock and other inputs. Households practising monodon culture made significantly more income, but faced high risk associated with shrimp mortality. An investigation of the factors affecting monodon yields indicated that investment in higher quality inputs had a positive effect on yield and income. However, further research is needed on the extent to which management can reduce risk of shrimp mortality by investing in such premium quality inputs.  相似文献   

13.
    
Shrimp polyculture is not yet a common practice among farmers; however, this activity represents an important alternative to solving and/or minimizing some of the problems that shrimp aquaculture has faced in the past two decades (environmental pollution, diseases and decreasing prices). In this context, many benefits have been achieved with some polyculture practices. Several species from diverse trophic levels have the potential to be co‐cultured with shrimps. A good knowledge of the species that are candidates for polyculture and an adequately designed culture system are the most important points to consider when co‐culturing shrimp with other species. The present paper is a review of the past, present and future of shrimp polyculture with other organisms.  相似文献   

14.
    
Shrimp farming in India has developed at an uneven pace since export-oriented production began in the early 1990s. The introduction of Penaeus vannamei in 2009 along with disease-related production declines in competing Asian nations has led to a remarkable expansion in recent years. It is clear that the long-term success of Indian shrimp farming will continue to rely on the widespread adoption of Better Management Practices (BMPs). A two-round stakeholder Delphi survey was conducted in 2012 to elicit views and build consensus on the relative importance of a comprehensive set of BMPs covering most aspects of shrimp farming production. While the vast majority of BMPs were considered important, respondents placed greater emphasis on those BMPs aimed at improving production efficiency. Also, BMPs focused on overall outcomes were ranked higher than those placing specific restrictions on input usage. Results also yielded interesting policy implications on BMPs that are yet to be widely adopted such as distance between farms and construction of effluent treatment systems.  相似文献   

15.
文章调查了广东省汕尾市红海湾对虾精养池塘水体中不同形式的碳（C）、氮（N）和异养细菌含量的变化,并分析c和N对异养细菌的影响,以期为养殖过程合理调控水质环境提供理论数据。结果发现,池塘中不同形式的P（C）在养殖前、中期逐渐升高并达到最大值,中、后期缓慢下降趋于稳定,P（N）在养殖前、中期较低,后期升高并达到最大值;异养细菌数在养殖中期的第56天和养殖后期的第98天出现2个高峰,养殖第70天出现低谷。异养细菌数与总无机碳（TIC）和总碳（TC）呈现极显著正相关关系;养殖中、后期异养细菌数与C／N（TOC／TN）呈极显著负相关关系。结果表明,养殖中、后期水体中C（主要是有机碳）成为影响异养细菌繁殖的限制性因素,适当添加C源可以促进异养细菌繁殖,吸收转化无机氮,从而达到降低水体中无机氮浓度、提高物质循环利用效率的作用。  相似文献   

16.
    
The implementation of the voluntary adoption of the Code of Conduct (CoC) to promote environmental responsibility and sustainable development of Thai shrimp industry is examined. Farmers' perceived benefits, risks and uncertainties associated with the adoption and their perceived extra fixed cost are found to be the critical conditions to the success of the program. Improvement of farmers' perceptions through increased information and knowledge, development of supportive policies and mechanisms (i.e., a “Group CoC” system, insurance program, a combination of environmental policy approaches) and strengthening farmers organizations, as well as establishing networks among and between the players throughout the market chain are suggested to enhance the adoption and implementation of the scheme.  相似文献   

17.
The annual increase in farmed freshwater prawn production in the world during the decade ending 2001 has been estimated as 29% and that during 1999–2001 as 48%, the production in 2001 being about 300 000 mt (all Macrobrachium species). Between 1999 and 2003 the annual increase in farmed Macrobrachium rosenbergii production in India was about 80%, production reaching 30 450 mt in 2002–2003. This log phase of production followed the rise and fall of shrimp farming in the country. Several shrimp farming ventures collapsed in the 1990s, owing to degraded environment and diseases, abetted by lack of awareness and inadequacy of information on the culture systems and their interactions with other human endeavours. This shrimp farming experience has made the aquafarmer and other stakeholders aware that while aquaculture has a high potential in ensuring food and nutritional security and livelihood, besides profit to the farmer and socio‐economic benefits to local communities, it is likely to slip from sustainable development pathways if adequate understanding, improved management practices, governmental policies and plans for implementation and regulation to ensure sustainability are not in place. The lessons learned from shrimp farming can help in steering the development of sustainable freshwater prawn aquaculture in India and elsewhere.  相似文献   

18.
Small-scale shrimp-culture is an important livelihood for rural residents in Thua Thien Hue (TTH) province, central Vietnam. However, they are facing the risk of exclusion from the food system due to globalization and trade liberalization. To keep these farmers in modern supply chains, their relationships with other chain actors, foremost the collectors, need to be improved. Thus, this study explores the characteristics and constructs of the relationships between the small-scale shrimp growers and their collectors. Data was based on a survey on 83 small-scale shrimp growers, together with 16 unstructured interviews with growers (10) and collectors (6). It was revealed that the relationships between small-scale shrimp growers and collectors in TTH province are short-term and price-driven and are influenced by the power of collectors. The relationship strength was measured by five intercorrelated constructs including reliability, willingness-to-maintain, desire-fulfilment, negotiation capacity, and discussion capacity. Although some constructs were positively correlated, the strength of the relationships was weak. Both business linkages and social connections affected the grower-collector relationships. Female traders had stronger relationships with collectors than males. Therefore, interventions should be focused on business and social linkages as well as females’ involvement in shrimp trade.  相似文献   

19.
    
The aim of this study was to evaluate the short‐term effect of probiotic inoculation on the abundance of heterotrophic and ammonia‐oxidizing bacteria in mature biofloc, as well as on total suspended solids (TSS), chlorophyll‐a and nitrogenous compounds in water. A completely randomized design consisting of five treatments (three commercial probiotics, one native consortia and one control) was performed. At the beginning of the experiment (day 1), each treatment was inoculated with the respective probiotic: PondPlus® (PP), Efinol® PT (EF) and Epicin® ponds (EP), native consortia UE, whereas the control was not inoculated. Water parameters and bacterial abundance were evaluated at 0, 2, 4, 6 and 8 days. The addition of probiotics, either native or commercial, did not show any significant effect on the TSS, Chl‐a and colony‐forming unit (CFU) of heterotrophic bacteria when they were added to the systems containing mature biofloc. A significant increase in ammonium oxidizing bacteria was registered with the probiotics PP and EP, although the levels of total ammonia nitrogen, NO3‐N and NO2‐N were statistically similar among all treatments. Modifications on most of the parameters measured were associated with the factor of time, rather than the inclusion of probiotics. Results suggest that the bacterial conglomerates in mature stage contain well‐established bacterial communities that are difficult to be affected by the addition of probiotics.  相似文献   

20.

以在盐度2~3条件下养殖至9月龄的凡纳滨对虾( Litopenaeus vannamei )成虾为材料, 研究低盐度养殖对虾在不同盐度驯养条件下的繁殖性能, 以期为利用低盐度养殖对虾培育亲虾提供科学依据。实验盐度梯度设置为1、8、15、23和30。雌虾经剪切单侧眼柄后进行促熟培育, 促熟期间的雄虾养殖水温控制在(27±0.5)℃, 雌虾水温控制在(28±0.5)℃。定期检查雌虾卵巢和雄虾精荚的发育情况, 采用精荚人工移植技术对不同盐度条件下培育的亲虾进行组合交配, 统计受精率和孵化率, 组织切片观察卵巢发育, 综合评价各实验组合的繁殖性能。结果表明, 在实验盐度梯度范围内, 雌虾卵巢都可发育成熟; 盐度1组雌虾成熟比例仅10%, 且全部死亡; 盐度8和15下发育成熟的雌虾达70%, 可正常产卵, 但产出的卵子受精率较低, 不能孵化出无节幼体; 盐度23和30下发育成熟的雌虾超过76%, 可正常产卵、孵化, 但孵化率较低。组织切片观察, 盐度8~30范围内各组雌虾卵巢发育无明显差异。在盐度8~30范围内, 凡纳滨对虾雄虾精巢都能够正常发育成熟, 但盐度30和23实验组的雄虾精巢发育速度明显快于盐度15和8组; 随着盐度的降低, 精荚发育成熟所需要的时间明显延长; 所有盐度实验组的精荚被移植后都可与卵子受精并孵化出无节幼体。

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