Emergy evaluation and economic analysis of three wetland fish farming systems in Nansi Lake area, China.
Emergy evaluation and economic analysis of three wetland fish farming systems in Nansi Lake area, China.
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DOI：
10.1016/j.jenvman.2010.10.005
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发表时间：
2011-03
影响因子：
8.7
通讯作者：
Lixiao Zhang;S. Ulgiati;Zhifeng Yang;Bin Chen
中科院分区：
文献类型：
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作者：
Lixiao Zhang;S. Ulgiati;Zhifeng Yang;Bin Chen
采用能值法和经济法对2007年南四湖地区网箱养鱼系统、池塘集约化养鱼系统和半自然粗放式池塘养鱼系统3种鱼类生产模式进行了评价和比较。本研究的目的是从生态学和经济学的角度了解所选鱼类生产模式的效益和驱动力。该研究考虑了投入结构、生产效率、环境影响、经济可行性和可持续性。结果表明，三种生产系统之间的主要差异在于与其饲养系统相关的鱼饲料能量成本，即以浮游生物和草等天然生物质为食或以商业原料为食。从EYR、ELR和ESI可以清楚地看出，以商品饲料为主的集约化生产模式是不可持续的。然而，问题是，较无害环境的模式似乎不能在短期内提供有竞争力的净利。集约化池塘养鱼系统的净利润为2.57E+03 $/ha，远高于网箱养鱼系统的1.27E+03 $/ha，略高于半自然养鱼系统的2.37E+03 $/ha。在影响当地农民决策的驱动因素中，土地的可得性和投资能力决定了农民对生产模式和经营规模的选择，而其他因素似乎影响不大。从理论上讲，迫切需要发展环境上可持续的生产模式，即节水和土地节约措施、更环保的饲料以及低废物系统，以使生产活动保持在生态系统的承载能力之内。结合能量和经济分析可以更好地了解鱼类生产系统的环境和经济效益，并有助于解决政策制定过程中遇到的问题。
Emergy and economic methods were used to evaluate and compare three fish production models, i.e., cage fish farming system, pond intensive fish rearing system and semi-natural extensive pond fish rearing system, in Nansi Lake area in China in the year 2007. The goal of this study was to understand the benefits and driving forces of selected fish production models from ecological and economic points of view. The study considered input structure, production efficiency, environmental impacts, economic viability and sustainability. Results show that the main difference among the three production systems was the emergy cost for fish feed associated with their feeding system, i.e., feeding on natural biomass such as plankton and grass or on commercial feedstock. As indicated by EYR, ELR and ESI, it can be clearly shown that the intensive production model with commercial feed is not a sustainable pattern. However, the point is that more environmentally sound patterns do not seem able to provide a competitive net profit in the short run. The intensive pond fish farming system had a net profit of 2.57E+03 $/ha, much higher than 1.27E+03 $/ha for cage fish farming system and slightly higher than 2.37E+03 $/ha for semi-natural fish farming system. With regard to the drivers of local farmer’s decisions, the accessibility of land for the required use and investment ability determine the farmer’s choice of the production model and the scale of operation, while other factors seem to have little effect. Theoretically, the development of environmentally sustainable production patterns, namely water and land conservation measures, greener feed as well as low waste systems is urgently needed, to keep production activities within the carrying capacity of ecosystems. Coupled emergy and economic analyses can provide better insight into the environmental and economic benefits of fish production systems and help solve the problems encountered during policy making.