Abstract:

In order to properly guide production activities of the pondfarming freshwater shrimp by the environmentally friendly efficiency standard, employing Slacksbased Model (SBM model) and CCR model, this paper took the impact of freshwater aquaculture on water quality into consideration, calculated the usages of all inputs, environmental efficiency and economic efficiency and compared the results by correlation analysis, paired sample t test and homogeneity test of variance. The SBM model was proved to be the best method to measure the environmental efficiency, because it could solve problems of weak disposability, restriction of convexity and slackness. The input elements of freshwater shrimp farming consisted of land rent, young shrimp, feed, fertilizer, electricity, drug, labor and machines. The desired outputs were the yield of adult shrimps and the nitrogen and the undesired outputs were phosphorus discharged. The undesired outputs were calculated based on balance principle of the material. The analysis was based on 183 decision making units engaged in pure freshwater shrimp pond farming in Jiangsu Province listed as the first province of freshwater farming. The results showed that environmental efficiency of pondfarming freshwater shrimp (economic efficiency including environmental cost) was only 0476 9 with 31 decision making units on the efficient frontier, while traditional economic efficiency (economic efficiency exclusive of environmental cost) was 0.6967. They were significantly positively correlated with similar distributions, but the former was significantly lower than the latter and appeared stronger volatility. Therefore, compared with economic efficiency, it was harder to reach the frontier of environmental efficiency through controlling the freshwater shrimp farming elements. The fundamental reason was the ignorance of environmental cost in farmersresources allocation，because farmers were economic men, they cared about the personal shortterm economic benefits rather than the environmental protection or the longterm development of industry that has the nature of public products. Therefore, environment impact should be taken seriously. All the inputs were excessively used. There were diseconomies of scale in freshwater shrimp pond farming. The overuse rates of the inputs in the two efficiencies were quite different. Apart from electricity, young shrimp cost and drug cost, the overuse rates of other inputs in environmental efficiency were higher than those in economic efficiency, especially labor and machine input, which have the nature of fixed cost. Lower utilization rate resulted in more excessive fertilizer input than feed input. The overused rate of young shrimp input was higher in economic efficiency than that in environmental efficiency. Raising the breeding density could not improve the economic efficiency greatly