| Aquaculture is the world’s fastest growing food production sector. If consumption levels remain unchanged, the global seafood supply has to increase to 37 million tons in order to satisfy people’s consuming demand in 2030. The biggest challenge aquaculture facing is to meet rapid growing and expanding needs under the premise of sustainable development. Unlike capture fisheries, aquaculture has great potential to increase the seafood supply, thus to meet the people’s growing demand for fish product. With the limit of restricted water and land resources, the increasing seafood supply relies on the improvement of produce efficiency. At present, because of the free charge of pond water in aquaculture, domestic farmers usually adopt high-density and high-yield pattern of pond fish culture in order to increase the output. This culture pattern leads to high amount of feeding and the frequent exchange of pond water in aquaculture. The surplus bait and high volume of feces exacerbate the environmental pollution of pond, thus result in the over input of pesticide and slow growing of tilapia. The final consequence is to lower the produce efficiency of aquaculture and decrease the quality of seafood. China is the largest aquaculture country in the world, supplying more than 80 percent of global aquaculture products. Today eutrophication problem of aquaculture itself has been a serious threat to water quality and safety, as well as aquatic products quality and safety.This dissertation takes tilapia pond culture as the example to analyze the present produce efficiency and environmental efficiency of aquaculture and their influencing factors. The improvement of corresponding influencing factors will promote produce efficiency,increase farmers’ income, meanwhile reduce pollution and protect environment and water resources. This dissertation provides theoretical and practical basis for the sustainable healthy development of tilapia pond culture,aquaculture,are well as the agricultural sector, for harmonious development of environment, resources, economy and society, for promoting the conservation of resources, increasing supply volume and quality of seafood and market competitiveness, securing people nutrition safety, reducing production costs of aquatic products, enhancing farmers’ income and improving their living standards.Theoretical analysis includes produce efficiency analysis, farmers’ behavior analysis and relations between agricultural development and environmental pollution.On the basis of introducing production efficiency, technical efficiency and environmental efficiency theory and farmer behavior theory, this study analyzes the motivation (induced condition) of aquaculture pollution. Natural attributes of aquaculture,market attributes and market failure caused the more and more serious environmental pollution of aquaculture. In the drive of maximizing profits, the farmers adopt the advanced technology, intensive, specialized production aquaculture pattern to improve output (desired output) and also increase the output environmental pollution (undesired output). The quasi-public property of water resources, the negative externalities of discharged pollution and positive externalities of water pollution treatment of aquaculture provides conditions of environmental pollution existence. The lack of market regulation provides living conditions for aquaculture pollution. Water resources are essential inputs for aquaculture. However, the cumulative environmental pollution of aquaculture year after year deteriorates the quality of surround water resources, thus causes the frequent disease in breeding process of aquaculture products. The sequence is that the volume of fishery drugs has to be increased and the quality of aquaculture products inevitably decreased. Compared with clean water, deteriorated water quality dissolves relatively low volume of oxygen, thus the number of released fish fry is restricted. Therefore, the reduction of output is certain. Hence, environmental pollution has impact on both output quality and quantity. The combination of input factors in aquaculture technology affects not only the produce efficiency but also the environmental pollution output. The direct consequence of environmental resources deterioration is to increase the usage of fishery drugs, thus increase the possibility of seafood unsafety. In this sense, reducing the environmental pollution of aquaculture may lead to the less input of fishery drugs,increase the dissolved oxygen and enhance the quality and quantity of aquaculture products.The analysis of traditional economic cost and environmental economic cost forms the foundation of single factor utility efficiecy.In order to avoid the deviation caused by the diversity of waters, taking tilapia pond aquaculture for example, this study analyzes the produce efficiency of aquaculture. On the basis of cost-benefit analysis, three patterns of tilapia ponds culture --- monoculture,polyculture and IMTA (Integrated Multi-Tropical Aquaculture) --- are studied. First cost analysis of the three culture models are conducted, focusing on examining the difference between traditional economic costs and environmental economic costs. In general,environmental costs are higher than traditional economic costs. Therefore, the analysis of tilapia pond culture only from the perspective of traditional economics is insufficient.The environmental pollution costs are borned by society this fact results in the more and more aquaculture pollution. Comparing single-factor produce efficiency of different models of tilapia ponds cultures, this study finds that factor productivity of different aquaculture models vary greatly. The labor productivity of monoculture is the highest,indicating that specialized production promotes labor productivity, in line with Adam Smith’s theory of labor division. If only considering tilapia production,land productivity of polyculture is the lowest among the three models, because other the economic fishes consume the land resources. If taking all products into consideration, land productivity of polyculture is the highest, this attributes to hierarchical utilization of waters and reasonable allocation of fish species. The environmental costs of IMTA are comparatively high, because manure of livestock and poultry replaces certain part of forage, increasing the emissions of nitrogen and phosphorus. Due to the difficulty in controlling the technology and input volume of-forage under the model of IMTA, labor productivity and land productivity are comparatively lower than that under polyculture.In general, under all model of cultures, single-factor productivity is low. Therefore, it is the common problem in aquaculture under all cultural models. To promote the productivity, first thing that should be done is to enhance the utilization efficiency of input factors.Compare the produce efficiency acquired by different empirical models under different aquaculture models.DEA and SFA models are employed to assess the productivity of tilapia ponds culture. The results indicate that differences between the two models are little. Both of the produce efficiencies of the two models are very low. The differences among different models of aquaculture are also little and the distributions of the results are very close. In any model of aquaculture, there are very few in the decision-making units on the efficiency frontier and the vast majority of farmers are at the low efficiency level, thus in urgent need of significant technological improvements. All in all, it is a common problem that the produce efficiency of tilapia ponds culture is low. Sensitivity analysis of input factors under DEA model and the output elasticity of input factors under SFA model both imply that the inputs of machines have significant negative impact on produce efficiency,indicating an excessive amount of machines or irrational usages of machines. Though the impacts of other factors on produce efficiency under the two models rank incompletely the same, both show the input of forage and fish fry has greater impact on the promotion of produce efficiency and that of land and labor impacts comparatively less. From the perspective of factor inputs, enhancing the utilization efficiency of forage and the quality of fish fry can contribute to the improvement of produce efficiency of tilapia ponds culture. All survey data show that in any breeding patterns, only a small part of farmers achieve full efficiency or high efficiency level, while most farmers have a very low produce efficiency. This indicates that no matter what culture model farmers adopt, there is a large room to enhance production efficiency of aquaculture from technical perspective.Calculate economic losses caused by acquaculture and acquaclture environmental efficiency.According to macro data from provinces of Jiangsu, Guangdong and Hainan, this study calculates the total volume of environmental pollution discharged by aquaculture(tilapia pond culture) from year 1990-2012. Provided that market prices of nitrogen and phosphorus are no more than the cost of pollution treatment, this study also calculates the economic losses caused by tilapia culture in the three provinces above mentioned. Then SBM model is employed to analyze the environmental efficiency of tilapia pond culture,that is,to contain the pollution in the total output. Empirical analysis shows that the environmental efficiency of tilapia ponds culture is lower than technical efficiency of both DEA model and SFA model. This fact implies that farmers pursuing the maximization of economic profits are at the cost of sacrificing surround environment.This kind of behavior is in accordance with the behavior theory of economic farmer. Few farmers have a comparatively higher environmental efficiency than technical efficiency due to much attention on Eco aquaculture or free-range pattern. Farmers adopt free-range pattern mainly because the deterioration of environment or the small margin of aquaculture income. Very few farmers achieve the optimum of environmental efficiency and technical efficiency. This is the best state of aquaculture. The significant and positive impact of technical efficiency on environmental efficiency indicates that improving technical efficiency is a good way to enhance technical efficiency.Regression analysis discloses the path of enhancing produce efficiency and environmental efficiency.Finally, ordinary least squares (OLS) regression model is adopted to analyze factors influences of production efficiency and environmental efficiency. Results show that technical efficiencies of both DEA model and SFA model have significant and positive impact on environmental efficiency. The essential determinants of produce efficiency are technical efficiency, quality of fish fry, water treatment, silt treatment, technology training and the policy of agricultural subsidy. The educational level of farmers also has positive impact on produce efficiency. Among the three cultural models, monoculture has greatest impact on produce efficiency. However, polyculture has greatest impact on environmental efficiency. The current IMTA has comparatively lower impact on both produce efficiency and environmental efficiency. Therefore, it is not the modern green circulated aquaculture model, but traditional aquaculture model. Combining channels of enhancing both produce efficiency and environmental efficiency, the common key way is to promote technical efficiency. How to improve technical efficiency? Improving farmers’ education level, joining cooperatives, adopting high quality fish fry, treat aquaculture water and pond silt is the way to promote the technical efficiency of DEA and SFA models.In summary, this paper presents the following countermeasures to increase tilapia supply and enhance the quality of tilapia products. Monitoring and management measures of environmental pollution on aquaculture farmers shall be taken. Measures of guidance farmers to improve technical efficiency shall be implemented such as promotion pollution treatment, implementation of environmental pollution subsidy mechanism,establishment of a sound technical support system in order to push the farmers to culture high-quality fish, and improve technical efficiency and environmental efficiency. |
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