Comparison of intensive shrimp farming systems in Indonesia, Philippines, Taiwan and Thailand

The estimated production of cultured shrimps for 1995 in Taiwan, the Philippines, Indonesia and Thailand was 20 000, 40 000, 80 000 and 220 000 tonnes, respectively. Intensive shrimp ponds in the Philippines (71%) and Indonesia (63%), which are developed in the tidal and mangrove areas, cannot be properly treated by complete drying, owing to seepage from supply and drainage, nor by removal of the fouled layer by heavy machines such as bulldozers. Intensive farms in Thailand and Taiwan are owned by small-scale operators operating 2-3 ponds simultaneously, each ranging from 0.16 to 1.0 ha, which is the optimal size for efficient farm management and lower overhead and investment costs compared with larger farms such as those found in Indonesia and the Philippines. In Taiwan, 90% of pond water supply is mixed open sea water with underground fresh water. Pond salinity, which is kept constant at 10-15%o, causes Taiwanese farmers to encounter an array of problems which include high cost of underground water pumping, land subsidence, salinization, more pathogens and rapidly fouled bottom. Water loss by seepage in Thailand is minimal (average 23 cm in the final month), compared with Indonesia and the Philippines, because pond dikes are tightly compacted by heavy machines and high clay content (86%). Circular water movement in ponds in Thailand, facilitated by heavy aeration (13.3 hp ha^?1), aids in the settling of waste in pond centres for easy removal. Indonesia and the Philippines still maintain high water exchange systems (335 cm and 470 cm in the final month, respectively) which introduce viruses, other pathogens, excess organic loads, ammonia and other toxic particles released by nearby farms through the incoming water. Despite serious crop failures in other countries within the past few years, the annual shrimp production in Thailand still remains high because farmers have readily adopted new, environmentally friendly and locally suitable, water exchange systems such as less water exchange, and closed, full-strength seawater and freshwater systems, overcoming heavy viral and disease infections. Approximately 30% of shrimp production in Thailand comes from the freshwater areas, sometimes 200 km from the sea. Half of the Philippine farmers rely on imported feeds; this has caused high shrimp mortality owing to toxins produced from expired feeds kept in humid conditions.     

Production risk of pangas (Pangasius hypophthalmus) fish farming

Pangas is a relatively new and fast-growing fish species that has great potential for production and export growth in Bangladesh. However, production variability exists from farm to farm and location to location, which indicates that production risk may be a problem in pangas farming. Research on production risk is therefore of great importance, especially for small-scale farming systems in developing countries, where farmers are more vulnerable to risk. This study investigates the production risk of pangas farming in selected areas of Bangladesh. A Just–Pope stochastic production function is chosen to estimate the mean and risk functions. The test result shows that significant production risk exists in pangas farming, and that the risk differs between small and large farms.     

影响中国农产品总产量的主要因素分析——基于农户经营方式的视角

从农户经营方式的角度看,弱质劳动力务农、劳动力兼业经营和农业规模经营是影响中国农产品总产量的三个主要因素。采用国内外的相关数据分析这三个因素对农产品总产量的影响,结果表明,不同质劳动力利用和农业劳动力兼业不一定会影响农产品总产量,农户的粮食规模种植模式也不是必然提高国家的粮食总产量。由此得出,中国农产品总产量水平主要是由当前技术水平所决定的;农业规模经营方式中,如果农户收入最大化通过总的规模收益实现,不利于国家主要农产品安全目标的实现;家庭农场的建立应趋利避免害,避免复种制度改变对农产品总产量的影响。     

Technical efficiency of different farm sizes for tilapia farming in China

China is the world's largest tilapia producer. This study uses the stochastic frontier function in the Cobb–Douglas model to evaluate a production frontier for tilapia aquaculture and analyses the relationship between farm size and production efficiency in China. A random sample of 300 tilapia farmers was surveyed in the main tilapia‐producing areas to study their economic efficiencies. The percentage distribution of tilapia farm technical efficiency was determined, with an average efficiency of 79%, which showed that the sample tilapia farmers operate at 21% below the production frontier and hence that they still have a chance to achieve targeted yields. The technical efficiencies of two categories (≤1 ha and >1 ha) were 78.82% and 79.27% respectively. A second‐stage analysis investigated the relationship between farm size and technical efficiency and showed a positive relationship between farm size and production efficiency based on the ordinary least‐squares model. The optimal farm size was found to be 7.50 ha. This study proposes strategies such as enlarging the farming scale moderately, thereby achieving the advantage of economies of scale, and enhancing the competitiveness of the tilapia industry in China.     

循环水系统结合鱼菜、紫外处理对镜鲤生长及水质的影响

为探索绿色环保的循环水养殖模式,设计循环水鱼菜共生系统(鱼菜组)、紫外灯鱼菜共生系统(鱼菜紫外灯组)及循环水养殖系统(循环水组),比较三种不同处理方式对镜鲤(Cyprinuscarpio var.specularis)、叶用莴苣(Lactuca sativa var.ramosa)生长和养殖水质的影响。结果显示,鱼菜组、鱼菜紫外灯组处理对镜鲤的生长无显著影响,但会显著影响镜鲤形态学指标,鱼菜组镜鲤肠体比显著低于循环水组。体成分方面,鱼菜组全鱼粗蛋白、粗脂肪显著高于循环水组,鱼菜组肝脏粗蛋白显著低于循环水组。鱼菜紫外灯组的细菌总数显著低于鱼菜组。水质方面,鱼菜组、鱼菜紫外灯组可显著降低系统中氨氮、硝酸盐氮及总磷总氮含量,鱼菜紫外灯组硝酸盐氮、总磷及总氮含量显著高于鱼菜组。综上所述,循环水系统耦合水培蔬菜单元可改善系统水质,改善鱼体成分,并且结合紫外灯处理可降低水体细菌总数。     

Technical efficiency of carp production in Nepal: An application of stochastic frontier production function approach*

Abstract

Modern aquaculture is a relatively new activity among Nepalese farmers and a small contributor to the economy. Given the abundance of water resources and fish species, rising demand for fish, and its high profitability, aquaculture has potential for future expansion if it is given appropriate attention from the government. In Nepal, productivity in aquaculture is much lower compared to other countries in the region, which suggests that there is potential for increased fish production through technological progress and improvement in farm‐level technical efficiency. However, no formal analysis has yet been conducted to assess the productive performance of Nepalese aquaculture and its potential for future improvement. Against this background, this paper examines the technical efficiency and its determinants for a sample of fish pond farms from the Tarai region of the country using a stochastic production frontier involving a model for technical inefficiency effects. The estimated mean technical efficiency is 77%, with intensive farms being more efficient than extensive farms. The adoption of regular fish, water, and feed management activities has a strong positive effect on technical efficiency.     

Production risk,technical efficiency,and input use nexus: Lessons from Bangladesh aquaculture

The optimal use of resources in aquaculture is important, especially in developing countries, to obtain the highest possible outcome from the production process to support food security and poverty alleviation. Thus, within this study, the risk, efficiency, and input‐use variation in aquaculture farms in Bangladesh is investigated using a flexible stochastic frontier model with a risk and an inefficiency function. The results reveal that feed, labor, and capital have positive and significant impacts on production. In addition, an increased fingerling density and a larger farm increase the risk, whereas the use of feed and the capital invested have the opposite effect. Access to extension services has a positive effect and increases farm efficiency. An investigation of the farm size–productivity inverse relationship reveals that this phenomenon is not applicable to Bangladesh aquaculture. In general, efficient farmers are large‐scale farmers, who use a lower stocking density but a higher feeding intensity, resulting in a higher yield. On average, farmers use less labor and feed than what is optimal. To increase efficiency and reduce risk, it is recommended that more technical knowledge on optimal input use, extension service, and capital is made available to aquaculture farmers.     

Profitability and technical efficiency of aquaculture systems in pampaanga,philippines

Abstract

We evaluate the profitability and technical efficiency of aquaculture in the Philippines. Farm‐level data are used to compare two production systems corresponding to the intensive monoculture of tilapia in freshwater ponds and the extensive polyculture of shrimps and fish in brackish water ponds. Both activities are very lucrative, with brackish water aquaculture achieving the higher level of profit per farm. Stochastic frontier production functions reveal that technical efficiency is low in brackish water aquaculture, with a mean of 53%, explained primarily by the operator's experience and by the frequency of his visits to the farm. In freshwater aquaculture, the farms achieve a mean efficiency level of 83%. The results suggest that the provision of extension services to brackish water fish farms might be a cost‐effective way of increasing production and productivity in that sector. By contrast, technological change will have to be the driving force of future productivity growth in freshwater aquaculture.     

Assessment of a biofilm‐based culture system within zero water exchange on water quality and on survival and growth of the freshwater shrimp Neocaridina heteropoda heteropoda

The contribution of biofilm to water quality and as a food source for the culture of the freshwater shrimp Neocaridina heteropoda heteropoda was assessed in indoor aquaria using a zero water exchange system. Two successive phases were conducted to evaluate biofilm development on different substrates (polyethylene net: PN, plastic bottles: PET, agrovelo: AV) and the effect of biofilm to shrimps culture. The biofilm grown on all substrates helped to keep a good water quality by the uptake of nitrogen compounds and the production of high levels of dissolved oxygen associated to the proliferation of autotrophic microorganisms. High survival, reproduction and hatching of shrimps were achieved in all groups mainly associated with good water quality. Final biomass of the shrimps was significant higher for PN and AV groups; while specific growth rate and the levels of lipids of the shrimps yielded similar values for all treatments indicating that the three substrates allowed the growth of a biofilm that resulted in a healthy food source with similar nutritional value for shrimps. The results show that the production of N. heteropoda heteropoda could be successfully conducted by a biofilm‐based culture system with no water exchange, and thus contributing to a better water use. All materials tested were suitable substrates for biofilm growth, though AV and PET could reduce significantly production costs when compared to the PN. Moreover, by the recycling and reuse of waste materials (such as plastic bottles) could contribute to the development of a responsible, sustainable and environmentally friendly culture method.     

农户正规信贷可得性影响因素的实证分析——以陕西省756户农户的调查为例

农村金融市场普遍存在着农户“借款难”和金融机构“放款难”的两难局面。本文利用陕西省756户农户的调研数据,使用二分类Logistic模型来分析影响陕西省农户正规信贷可得性的因素,实证分析结果显示,被调查农户的文化程度、农户家庭年收入水平、是否购买农业保险、农信社对农户的信任水平以及农户违约后内疚程度对农户正规信贷可得性有显著的正效应;农户家庭负债水平、农户承担更大风险的意愿程度以及农户是否曾违约对农户正规信贷可得性有显著的负效应;被调查农户的年龄、农户的家庭总资产、耕地面积、家庭人口数,家中就读大学的子女数、是否有重病患者以及农业经营收入比例和农户支付更高利率的意愿对农户正规信贷可得性没有显著的影响。     

Tilapia–Shrimp Polyculture in Negros Island,Philippines: A Review

Tilapia–shrimp polyculture has played an important role in current efforts to control luminous bacterial disease caused by Vibrio harveyi. At present, green water technology is most extensively used by shrimp farmers in Negros Island in the central Philippines. While the contribution of tilapia as a biomanipulator is highlighted in the literature, the mechanism of action is not well understood. Data were gathered from shrimp ponds practicing two production systems: (a) green water system (probiotics + tilapia) and (b) closed/semiclosed system (probiotics alone). There was no difference between luminous Vibrio count (P < 0.05) in both systems, and water quality was found to be similar (P < 0.05). Because the green water system uses a bigger reservoir to raise the tilapia biomass, the net shrimp production was lower. In terms of direct cost of production, however, the green water system was 10–15% lower than the closed/semiclosed system because of significantly less aeration required. The polyculture maintained a more stable plankton environment during the early months of culture, which increased survival of shrimps. Various pathways are presented for the control of luminous bacterial growth in polyculture ponds: (a) fish feeding on organic wastes and conversion to feces; (b) selective fish foraging to increase the dominance of beneficial phytoplankton; (c) bioturbation of pond sediments; and (d) release in the water column of antimicrobials, fungi, or competing bacteria from the skin and gut mucus of tilapia.     

An assessment of alternative strategies for the integration of pond aquaculture into the small‐scale farming system of North‐east Thailand

Abstract

This paper uses a linear programming model to examine the economic viability of four fish production strategies in the context of rainfed farming systems in the north‐eastern region of Thailand. The four systems are rice bran feeding system, pond fertilization using buffalo manure, fish production recommendations developed by the Asian Institute of Technology (AIT) Recommendations and an integrated duck/fish production system. These systems have been introduced into North‐eastern Thailand where the main obstacles to fish production are the lack of indigenous knowledge offish culture and a shortage of water. While technical feasibility studies are needed to evaluate the practical viability of aquaculture technologies, economic assessment is required to assess their commercial viability. The objective of this paper is to examine whether or not these fish production systems can contribute to, and integrate with, the prevailing farm system in the North‐east of Thailand. The linear programming model is used to determine the optimum on farm product mix that maximizes net returns under each of the four production systems. Among different resources, labour requirement in the fish‐stocking month appeared to be the first binding resource, while capital requirement was not a constraint for an average farming household of the region. A sensitivity analysis is presented to show how each of the fish production systems operates with different levels of pond size, labour and capital availability. The results of the study show that these aquaculture systems are economically attractive and can contribute significantly to the livelihood of the small‐scale farmers of North‐east Thailand.     

Growth and reproductive performance of broodstock shrimp reared in a biosecure recirculating aquaculture system versus a flow-through pond

Over the past decade, viral pathogens have caused mass mortalities of farmed shrimp throughout the major shrimp farming regions of the world. In addition, the global shrimp farming industry has been criticized for negatively impacting coastal environments. These issues have raised concerns about the sustainability of traditional shrimp farming practices, and have prompted farmers and researchers to develop biosecure technologies that promote a sustainable industry. Current technologies include the use of specific pathogen free (SPF) shrimp that are grown to market size in recirculating systems that rely on pathogen exclusion. Inherent in this approach is the need to produce SPF broodstock under biosecure conditions. However, there is a paucity of information on broodstock growth and reproductive performance when they are reared in recirculating systems. The present investigation compares shrimp growth and reproductive performance in two trials where shrimp were cultured from market size (20 g) to broodstock size (40–60 g) in a recirculating aquaculture system (RAS) versus a flow-through earthen pond (EP). In trial 1, mean growth rates of males and females in the RAS were 0.83 and 1.33 g/week, respectively. In the EP, males and females grew 1.07 and 1.48 g/week, respectively. In trial 2, mean growth rates of males and females in the RAS were 0.90 and 1.53 g/week, respectively, whereas in the EP, males and females grew and 1.24 and 1.78 g/week. Slower growth rates in the RAS may be attributed to the lack of natural productivity, which provides supplemental nutrition to the shrimp. In addition to growth rates, reproductive performance of broodstock reared in the RAS was compared with historical reproductive performance of broodstock reared in the EP. Data on spawning success and production of viable nauplii revealed no significant differences (P>0.05) between broodstock shrimp reared in these two systems. These results indicate that broodstock shrimp can be cultured in a biosecure RAS while maintaining good growth and high survival. In addition, reproductive performance of broodstock shrimp reared in a RAS is not compromised when compared with broodstock shrimp reared in a conventional, flow-through pond.     

Influence of variation in water temperature on survival,growth and yield of Pacific white shrimp Litopenaeus vannamei in inland ponds for low‐salinity culture

There is considerable interest in the culture of whiteleg shrimp (Litopenaeus vannamei) in inland low‐salinity water in Alabama and other states in the Sunbelt region of the US. However, the growing season is truncated as compared with tropical or subtropical areas where this species is typically cultured, and temperature is thought to be a major factor influencing shrimp production in the US. This study, conducted at Greene Prairie Aquafarm located in west‐central Alabama, considered water temperature patterns on a shrimp farm in different ponds and different years; and sought possible effects of bottom water temperature in ponds on variation in shrimp survival, growth and production. Water temperature at 1.2 m depth in 22 ponds and air temperature were monitored at 1‐hr intervals during the 2012, 2013, 2014 and 2015 growing seasons. Records of stocking rates, survival rates and production were provided by the farm owner. Correlation analysis and linear mixed model analysis of variance were used. Results showed that hourly water temperatures differed among ponds. The range of water temperature in each pond explained 41% of the variance in average final weight of shrimp harvested from each pond. In conclusion, the results suggest that variation in water temperature patterns has considerable influence on shrimp growth and survival in ponds.     

Assessment of household risk management strategies for coastal aquaculture: the case of clam farming in Thaibinh Province,Vietnam

Clam farmers have experienced different types of risks that have been further exacerbated by the rapid expansion of clam farming areas, increased growing densities, and increased market difficulties in recent years in the Thaibinh Province of Vietnam. Most farmers have been seriously affected by production risk, market risk, and financial risk, while a number of others have met with success in almost all of their clam-raising cycles. This study applied a differentiating comparative analysis method and multiple discriminant analysis method to discuss the differences in risk management strategies between and among clam farming households and the impacts of those differences on their success/failure rates. In general, the tactics are related to increase in farm size, the application of technical innovations, diversifying livelihood activities, and accessing secure financial sources all provided better conditions for clam growth, diminished losses, and led to speedier recovery from shocks. To support farmers in managing risks, several government interventions are needed: (1) better re-zoning of clam farming areas in parallel with an increase in the farm size of each household, (2) promoting sustainable linkages between the farmers and the formal financial market and output market, and (3) investing more funding into research and extension related to sustainable clam farming practices and to the improvement of farmers’ skills in cooperative works and management.     

河湖水生态系统服务价值核算研究及应用展望

科学有效地界定河湖水生态系统服务价值评估体系与评估指标,可以促进河湖水生态的可持续发展、合理制定水资源价格、为河湖水生态系统服务价值评估提供参考,同时也为河湖水资源纳入国民经济核算体系提供借鉴,为绿色经济核算提供有力的依据。从河湖水生态系统服务功能、评估体系和评估方法等方面总结了国内外研究进展,分析了现有河湖水生态系统服务体系和评估方法的优缺点。对河湖水生态系统服务评估体系进行了优化,优化后的评估体系包括供给服务、调节服务、文化服务和支持服务4大类以及水资源供给、水质净化、科研教育和固碳能力等19项指标,优化了水资源供给、提供水产品、水质净化、防洪减灾、休闲娱乐、生物多样性保护等6个指标的评估方法。对河湖水生态系统服务价值核算在生态文明建设考核、生态产品价值实现机制、自然资源资产审计以及新时期河湖长制考核实施方面的应用进行了展望。下一步要制订GEP核算技术标准,建设市场化、多元化的生态产品交易体系,将水资源开发、利用及保护情况、水资源管理生态环境效益等指标纳入审计范围,建立以水生态系统为整体、以维护河湖生态系统健康为总目标、以定量评判和可操作性为抓手的新的河湖长制考核体系。     

ECONOMIC ASSESSMENT OF AN INTRA-SPECIFIC CROSS OF SILVER PERCH (Bidyanus bidyanus MITCHELL) FOR COMMERCIAL FARMING

The native freshwater silver perch, Bidyanus bidyanus, has the potential to form a large pond-based aquaculture industry in Australia, but at present, production is based on genetically un-improved stock. Research for improved growth rate has identified a significant level of hybrid vigor in fingerlings of the Murray River x Cataract Dam cross (MC). This study investigated whether the profitability of a commercial farm could be increased by using this intra-specific cross. Results indicate that silver perch bio-economics are sensitive to growth rate; use of MC increased annual return by AU$33,092, 20-year NPV by AU$324,895 and saved 56 days average grow-out. Cash flows became positive earlier for a farm using MC, which was also more risk efficient with only a 4% chance of making an annual return of less than AU$0. Although use of MC should result in improved profit to farmers, high feed costs and the small size of farms remain as major constraints to industry growth.     

Fish culture in rainfed rice fields of northeast Thailand

Adoption of rice-fish culture by farmers in the rainfed areas of northeast Thailand is examined with reference to recent field research and extension in the region. The practice is placed in perspective with the development of aquaculture per se and the human and agricultural ecology of this heterogeneous region. Rice-fish culture is a recent activity in the region and has been promoted by government and non-government agencies with variable success among small-scale farmers. The widespread availability of private hatchery-produced fish seed and perceived decline in wild fish have been important stimuli. Rainfed rice fields are marginal agricultural environments and lack of water constrains both rice and fish production. Wild swamp fish are tolerant of these conditions and traditional systems for their management and capture have expanded greatly in recent years. In much of the region ‘trap’ ponds are used more for catching wild fish than as refuge sumps or ponds for fish culture per se; wild fish typically constitute between 20 and 80% of the total yields in stocked systems. Widespread availability of fish seed allows more farmers to try rice-fish culture but the small size of seed at purchase is still a problem particularly where carnivorous, wild fish are prevalent. Appropriate on-farm nursery techniques may improve success and adoption of hapa nursing has been high in some parts of the region. Species ratio and density of fish stocked depends mainly on their availability from fry traders; the major species stocked in rice fields are the silver barb (Puntius gonionotus), common carp (Cyprinus carpio) and Nile tilapia (Oreochromis niloticus).

Farmers adapt rice fields for fish culture as part of their whole farm strategy; benefits to rice, vegetable and fruit and livestock may be considered more important than fish yields. The high value attached to even small quantities of fresh fish is a major incentive for rice-fish culture, but women who are decision makers in terms of changes to rice fields and household consumption have often not been fully considered during promotion of rice-fish.

The relatively small areas of riceland that farmers can stock and harvest fish, low yields per unit area and high consumption of fish reduces the importance of rice-fish culture in many rural households. The analysis suggests that stocking fish in rice fields in areas with poor access to wild fish supplies from community water bodies would have most impact.

Although rice-fish culture can contribute to subsistence requirements, the high labour demand often means that intensified capture of wild fish or pond-based culture of fish are more attractive for poorer and better off farmers, respectively.     

Supplementation of Chelated Magnesium to Diets of the Pacific White Shrimp,Litopenaeus vannamei,Reared in Low‐salinity Waters of West Alabama

Shrimp farmers using inland low‐salinity waters in west Alabama have traditionally used agricultural fertilizers (K‐Mag®, muriate of potash) to raise pond water levels of potassium (K) and magnesium (Mg) to improve the rearing medium for Litopenaeus vannamei. Laboratory and farm trials were performed to investigate the potential of using dietary supplementation of Mg instead of costly agricultural fertilizers. A 5‐wk laboratory trial was devised to test four diets with varying levels of Mg supplementation (0, 0.15, 0.30, and 0.60% Mg chelate) using a magnesium chelate (MgC)–amino acid complex. Juvenile shrimp were stocked into artificial low‐salinity water (5 ppt) designed to contain low levels of Mg. A farm trial was also conducted to test the same diets under field conditions. Although both laboratory and on‐farm trials revealed a trend for increased growth using the diet with the highest Mg supplement, results were not significantly different. The use of magnesium chelates as dietary supplements at levels higher than the requirement level to enhance survival, growth, and osmoregulatory capacity of shrimp reared in inland low‐salinity well waters appeared to have limited potential. Until effective specialized diet formulations are produced, farmers should continue to supplement pond waters with fertilizers containing K and Mg.     

Effects of different diets and seawater systems on egg production and quality of the broodstock Babylonia areolata L. under hatchery conditions

The broodstock of spotted Babylon snail, Babylonia areolata, were conditioned in indoor tanks under two seawater systems (static system and flow‐through system) and five types of foods (fish, shrimp, squid, green mussel and formulated diet). High survival and good feeding was found from broodstock conditioned in all treatments of seawater systems and diets. All broodstock showed active behaviour with no signs of stress as exhibited by active movement and feeding, protrusion of siphonal tube and constant egg laying throughout the experiment. Two‐way analysis of variance showed that there were no significant differences (P>0.05) in the total yield of egg capsules, size of egg capsules, size of newly hatched larvae and growth of larvae among broodstock B. areolata conditioned in the seawater system and diet treatments, but there were significant differences (P>0.05) in the frequency of egg capsule laying, number of fertilized eggs/embryos per capsule, total yield of fertilized eggs/embryos and final survival of larvae among broodstock B. areolata conditioned in the diet treatments. We present initial evidence that the seawater system had a stronger influence on the egg production and quality of broodstock B. areolata than conditioning diets.