基于层次分析法的我国罗非鱼养殖风险研究

罗非鱼养殖过程中面临很多风险,为了量化罗非鱼养殖风险的影响因素,评估养殖风险等级,以主产区罗非鱼养殖为例,分别从自然、市场、操作和政策四个方面,运用层次分析法和德尔菲专家调查法,建立风险评价指标体系,对各风险因素的影响程度打分,对两两因素相对重要性给出定量表示,整理并分析获得的数据资料。结果表明:我国罗非鱼养殖风险等级为B级,养殖风险很高,其中市场风险和自然风险是影响罗非鱼产业风险的重要因素,其次是政策风险,操作风险的影响程度最小。自然风险中以极端天气的影响程度最大,市场风险中受出口订单量的影响程度最大,操作风险中病害防控能力影响程度较大,政策风险中地方发展规划会极大地影响罗非鱼产业的可持续发展。     

PERCEPTIONS OF RISK AND RISK MANAGEMENT IN VIETNAMESE CATFISH FARMING: AN EMPIRICAL STUDY

Although Vietnamese catfish farming has grown at a rapid rate in recent years, the industry has also faced many problems that affect its sustainability. This paper explores the perceptions of catfish farmers regarding risk and risk management strategies in their production activities. The relationships between farm and farmer socioeconomic characteristics and perceptions of risk and risk management are also examined. Data for the study were collected in 2008 from a sample of 261 catfish farmers in the Mekong Delta, Vietnam using a questionnaire survey. The results show that, in general, price and production risks were perceived as the most significant risks. Farm management and technical measures were perceived to be more effective than other kinds of risk management strategies in risk reduction. Although price risks were rated as important, price risk management strategies were not perceived as important measures for risk mitigation. The results of the study are discussed to identify the implications for various industry stakeholders, including policymakers, processors, advisors, and developers of new risk management strategies.     

Clam farming quality as a management tool: A proposal based on recent studies in Northern Adriatic lagoons

The rapid and extensive spread of the clam Tapes philippinarum in Northern Adriatic lagoons, mostly in the lagoon of Venice (550 kmq), has led to severe exploitation by mainly free fishing, thus breaching the law. To contrast this unsustainable overexploitation, to which the present decreasing clam harvests are at least partly due, the local fishing authority has recently prepared a Master Fishing Plan for clam production, which is at present under way: the free fishing system must be replaced by a licencing system aimed at regulating market supply and mainly at converting more than 1000 fishermen into clam farmers. Moreover, a number of regulations for both vessels and harvesting techniques and management rules, such as daily clam harvests and fishing times, have been established. Although these newly introduced regulations may be regarded as valuable tools for preserving both the lagoon environment and the resource itself, they do not adequately consider protection for consumers. Although the licensed water areas have been evaluated as safe according to Italian law, at present no guarantees certify the quality of the clams harvested from them, due to the fact that the lagoon of Venice has polluted areas from which clams may be collected illegally and recycled to the legal market simply by putting them into the approved licensed areas before harvesting and marketing them. This paper therefore proposes a number of measures to be undertaken within the framework of good farming practices. The aim is to improve product quality by certification procedures in all production phases, and to guarantee the definite origin of farmed clams.     

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.     

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。     

Prediction of size-dependent risk of salmon smolt (Salmo salar) escape through fish farm nets

The escape of small smolt through farm cage netting is a major challenge faced by the Norwegian salmon farming industry. Escape can occur when the smolt placed in the cages are smaller than the size estimated by the farmers. Furthermore, one may assume wrong mesh-properties as the cage netting change shape and/or state from stiff (mesh bars with tension) to slack (mesh bars without tension) due to sea currents or waves and become more suitable for penetration. The latter represents an increased risk for cages placed in more exposed sea areas, which is a growing trend in the industry due to increased demand for farming sites. The potential influence of mesh shape and state on the risk of escape from salmon farm cages is predicted. The morphological characteristics of salmon smolt are assessed and used to determine the risk of potential escape through meshes of different sizes, shapes and states. The results showed that fish smaller than 47 g and 201 g have the potential to escape through 30 mm and 50 mm meshes, respectively. In general, the risk of smolt escape is highest when the meshes in the netting are slack. Semi-slack meshes with mesh openness of between 65 and 95 % also present a higher risk of smolt escape than square stiff meshes. The highest risk of escape was identified at approximately 80 % mesh openness. This study illustrates the importance of mesh states in fish farming cage nettings. In many cases the minimum smolt size needed to maintain an escape risk below 1 % was approximately twice as large for slack square meshes than for stiff square meshes of the same size.     

Development of an integrated aquafarming system

The integration of aquaculture into agricultural production systems to intensify profitable food production without the usual environmental degradation appears to be a promising option for a large number of small farmers in many developing countries. However, for the adoption of novel production systems, economic considerations are the main driving force. The farmer has to be convinced of the long- and short-term benefits and profits of different farming systems options. The potential farmer-aquaculturist needs site-specific holistic information packages of different production options, as contrasted with packages of technology only, in order to combine traditional knowledge with modern scientific results. These all-embracing data packages for different production systems must take into account the environmental conditions, the availability and price of the stocking material for aquaculture, of farm animals and seeds, seasonal farm and off-farm labour demands, and the socio-economic situation of the farmer and the neighbourhood. The possible production intensities, profits and risks have to be quantified, and the impacts on the environment, the family and society have to be determined. Such information would serve as a guideline for the selection of management options best suited to his/her farming system and would allow a choice of alternatives in case of unforeseen events. The multifaceted obstacles to developing a sustainable integrated aquafarming system are presented for a case in the Philippines.     

Mariculture of giant clams,Tridacna crocea and T. derasa: Management for maximum profit by smallholders in Solomon Islands

Abstract

The International Center for Living Aquatic Resources Management (ICLARM) has demonstrated that coastal village communities in Solomon Islands can successfully farm giant clams. The production technology is simple and does not require a large capital investment. The main inputs are clam seed, labour and time. Labour is used for activities such as planting, cleaning, thinning and harvesting. In this paper, a bioeconomic model is used to explore optimal farm management for two species of giant clam fanned for the aquarium and seafood markets. The theoretical basis for this analysis is found in the economic theory of optimal forestry exploitation. Optimal management involves finding the combination of the decision variables and the cycle‐length that maximises a stream of discounted profits. The decision variables considered here are husbandry which relates to cleaning, and the frequency with which thinning is undertaken. The optimal cycle‐length is determined for both a single‐clam harvest and multiple harvests for various management scenarios. The labour requirements for these management scenarios are identified for the multiple‐harvest case and input substitution between optimal combinations of labour and cycle‐length is investigated. Results indicate that profits are maximised for both species when husbandry is excellent and labour usage is most intensive. Thinning is only necessary for seafood clams for which the optimal cycle‐length is longer. Village farmers may not be profit maximisers however, and labour spent on giant‐clam farming takes them away from other activities. Rather than investing more labour and harvesting the clams earlier, a village farmer with other objectives may devote less labour and harvest the clams later, and spend more time on other activities. In general, these results are consistent with extension advice provided to village farmers by ICLARM. Optimal solutions were found to be very stable when incorporated into global optimisation routines and sensitivity analysis of a wide range of parameter values.     

Demonstrating the Use of Risk Programming for Aquacultural Farm Management:

A risk programming method that evaluates production plans based on expected income and risk was demonstrated using representative data from Panama. Results illustrate the usefulness of the program in presenting production choices to decision makers and evaluating those choices under changing conditions.
Less experienced or less financially secure farmers may select farm plans that differ quite importantly from those chosen by more experienced or more financially secure farmers. If farm survival is in doubt, more conservative farm plans will generally be adopted. Without consideration of the potential losses, it will often appear that all farmers should pursue the most intensive farm plan within their farming capabilities. However, many farmers will employ less intensive management strategies if the potential for losses associated with more intensive strategies is perceived to be excessive.
The model indicated that management strategies were sensitive to changes in shrimp price and feed cost, but less sensitive to the costs of post larvae or energy. Also, shrimp farm managers should give serious consideration to not producing in the dry season due to relatively high risk and low expected returns. Farmers should be most concerned with quality and availability of post larvae, not price. If hatcheries can address these concerns, the higher price of hatchery post larvae will be justified.     

ECONOMIC RISK ASSESSMENT OF A SEMI-INTENSIVE SHRIMP FARM IN SINALOA,MEXICO

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.     

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.     

The evolution of farm management,production efficiencies,and current challenges to catfish production in the United States

Abstract

The catfish industry is the most successful aquaculture business in the US. The development and growth of the catfish industry has resulted in complex fish farm businesses that require intensive management. Technological innovations have resulted in increased yields (land use efficiency). However, in more recent years, productivity gains have not kept pace with the rate of increase in input costs. Increasing intensification of catfish production over time has been accompanied by increased use of debt capital that results in higher levels of financial risk. While still a profitable activity, real profit margins have declined as financial risk has increased. New technologies will likely continue to increase productivity over time. Market‐oriented agribusiness approaches to catfish marketing are likely to become the norm. The challenge for the catfish industry is to coordinate adoption of new higher‐cost technologies with demand increasing market development to sustain farm price levels.     

Indoor Intensive Red Drum Aquaculture: A Stochastic Sensitivity Analysis

This research uses stochastic sensitivity analysis to examine an indoor intensive red drum aqua-culture facility. Important biological and economic factors are varied one at a time to determine the chance of survival and the chance of success. Results indicate that this type facility is very stable since all but one scenario had a 100% chance of surviving. This stability occurs because harvesting is spread uniformly through the year. Chances of being an economic success range from 0 to 100% depending on the investor's required rate of return and the assumed level of biological and economic factors considered in this analysis. An investor's interest in red drum farming will depend on his individual required rate of return, his management capabilities, the market conditions and his willingness to take a risk. It is certain, however, that a 0% chance of economic success will occur for a red drum farm under poor management.     

The Economics of Kappaphycus Seaweed Cultivation in Developing Countries: A Comparative Analysis of Farming Systems

The farming of the red seaweed Kappaphycus alvarezii and related species as raw material for the hydrocolloid carrageenan rapidly spread from the Philippines in the late 1960s to Indonesia, Tanzania, and other tropical countries around the world. Although numerous studies have documented positive socioeconomic impacts for seaweed farming, factors such as diseases and distance to export markets have led to an uneven development of the industry. Using standard budgeting techniques, this study adapted production and market data from a FAO-led global review of seaweed farming to develop comparative enterprise budgets for eight farming systems in six countries (Indonesia, the Philippines, Tanzania, India, Solomon Islands, and Mexico). Although the basic technology package is the same across countries, the study revealed large differences in the economic performance of systems due to wide variations in farm prices and the scale of operations. Although seaweed farming is a suitable activity for small-scale producers, a minimum of 2,000 m of cultures lines are still necessary to ensure adequate economic returns. Greater farming plots may be needed if farm prices are well below the average farm prices paid in Indonesia and the Philippines. Policy recommendations are made to improve the economic potential of underperforming systems.     

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.     

Socio-economic factors critical for intensification of fish farming technology. A case of selected villages in Morogoro and Dar es Salaam regions,Tanzania

Intensification of farm technologies has shown high potential in improving farm production and enhancing rural food and income security. Intensification, however, is commodity-specific with high-value crops intensively produced. Farmed fish is one of the high-value crops introduced in the study area to meet the above ends. The problem, however, is that the level of intensifying fish farming technology has been very low leading to discouraging results. A study was conducted in Morogoro and Dar es Salaam Regions, Tanzania, to identify socio-economic factors that influence the intensification of fish farming technology. Data were collected from 234 respondents randomly sampled from 25 selected villages and were analyzed using multinomial logistic regression model. Results indicated that age, extension education, profitability, marketability, risk, palatability and easiness to obtain farmed fish were significant in explaining the intensification of fish farming technology. Three recommendations emerge from this finding. First, there is need to provide extension education to the practicing farmers on various aspects of fish farming. The probability of intensifying fish farming is higher for knowledgeable farmers. Second, technology developers should strive to reduce the risk of farming fish and improve the profitability and marketability of farmed fish. Finally, any analysis focusing on intensification of a fish farming technology should not confine itself to agronomic and socio-economic characteristics but should also encompass food characteristics of the technology. Food variables such as palatability and easiness to obtain farmed fish have been shown to influence the intensification of fish farming technology.     

Establishing a benchmarking for fish farming – Profitability,productivity and energy efficiency of German,Danish and Turkish rainbow trout grow‐out systems

The promotion of Blue Growth in aquaculture requires an understanding of the economic drivers influencing the sector at farm level, but the collection of reliable and comparable data at this level is time‐consuming and expensive. This study suggests an alternative strategy for qualitative sampling of freshwater trout farms in Germany, Denmark and Turkey, using a combination of existing data, group discussions and interviews with trout farmers, consultants and researchers. Nine ‘typical’ trout farming models are described, focusing on profitability, productivity and energy efficiency and allowing in‐depth comparative economic analyses of different production systems at farm level, across regions. Our results show that the majority of the farms investigated have been profitable. Turkish farms benefit from competitive advantages due to low wages, low capital investment and favourable climate conditions. Large German farms profit from local market prices and advanced farm management. Danish farms using recirculating techniques remain competitive thanks to enhanced productivity and economy of scale. However, small traditional farms in Germany and Denmark may struggle to stay competitive in the long term. Organic farms in both countries face challenges of high feed costs and comparatively low productivity with mixed success. Using edible protein energy return on investment (epEROI) as an indicator of ecological sustainability, all surveyed farms compared very favourably with the terrestrial systems of animal meat production were investigated so far.     

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.     

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。     

Profitability evaluation of resource allocation for growing redtail and Chinese shrimp

A farming survey was conducted to evaluate the profitability of resource allocation for producing redtail shrimp, Penaeus penicillatus (Alock) and Chinese shrimp, P. chinensis (Osbeck). Data on production costs and total revenue according to different harvest sizes of shrimp species were collected based on 108 individual ponds operated by 25 surveyed shrimp farmers. The results indicated that growing Chinese shrimp to a marketable size of 12 g was the most profitable management strategy. The profits could be maximized by integrating small-scale farms to a 12.41 ha optimal farming area when the available resources remained the same as those for a 10 ha farm.