State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Beijing Normal University, Beijing 100875, PR China.
J Environ Manage. 2011 Mar;92(3):683-94. doi: 10.1016/j.jenvman.2010.10.005. Epub 2010 Oct 20.
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.
采用能值分析和经济分析方法，对中国南四湖 2007 年网箱养殖、池塘精养和池塘半自然生态养殖 3 种鱼类养殖模式进行了能值和经济分析，从生态和经济角度，探讨了不同养殖模式的效益和驱动力。结果表明，不同养殖模式的投入结构、生产效率、环境影响、经济可行性和可持续性均存在差异，其主要差异体现在养殖方式不同导致的饲料能值投入上，即分别以天然生物饵料（浮游生物、水草等）和人工配合饲料为食。从能值投入产出效率（EYR）、经济效率（ELR）和可持续发展指数（ESI）来看，精养模式和半自然养殖模式均不是可持续发展模式，而相对环保的养殖模式在短期内却难以获得竞争优势。池塘精养的经济效益最好，净产值为 2.57E+03 美元/公顷，高于网箱养殖的 1.27E+03 美元/公顷，略高于半自然养殖的 2.37E+03 美元/公顷。从养殖户选择养殖模式和决定养殖规模的驱动因素来看，土地资源的可获得性和投资能力是决定养殖户选择养殖模式和养殖规模的主要因素，其他因素影响较小。从理论上看，发展环境友好型养殖模式，如节约水资源和土地资源、开发绿色饲料、减少废物排放等，对于缓解养殖压力、实现养殖活动与生态系统承载能力相协调具有重要意义。能值与经济分析相结合，可为深入认识鱼类养殖系统的生态和经济效益、解决相关政策制定中的问题提供依据。
