Production Systems,Efficiency And The Impacts On Environment

Improvement of efficiency and reduction in pollution are two key objectives in pond aquaculture in China.The selection of aquaculture species and system plays an important part in achieving the development of green aquaculture.A high-intensive monoculture system has been established since decades ago and been developed rapidly in some of the main aquaculture areas.This single species dominated system,however,has received wide attention due to its potential loss in resource efficiency and environmental pollution.The study is conducted in Yancheng city,Jiangsu province,which has the largest yield of crucian carp in China,with our focus on the pond famers who practice intensive monoculture of crucian carp and those who practice polycuture of crucian carp and other'species.Within a framework of three correlated perspectives,i.e.,improvement of efficiency,economization of resources and reduction of pollution,this study aims to analyze the comprehensive performance of samples of crucian carp culture ponds using two-year short panel data collected in 2014 and 2015 respectively.The four topics are:(1)Analyze and compare the characteristics of different fish production systems and their performances of cost-benefit.Producers'behavior on the selection of systems is also analyzed.(2)The stochastic frontier cost function model is applied to measure cost efficiency and its determinants for the sample of crucian carp farmers.Cost efficiencies of different production systems are compared as well.(3)A multiple-output stochastic ray production frontier(SRPF)model is addressed to measure technical efficiency(TE)and its determinants for the sample of crucian carp farmers.Technical efficiencies of different production systems of crucion carp are also compared.(4)Multiple Linear Regression is applied to investigate the impacts of production systems on utilization efficiency of resources and environment performance,aiming to provide supports on the earlier empirical results in this study and some reference for improving producing efficiency and reducing pollution.The conclusions of this study are:(1)As regards to the factors of production inputs,the mean level of feed input and level of total production inputs of monoculture system are both significantly higher than that of polyculture system,while the former system can economize more labor input than the latter one.The monoculture system is superior to polyculture system according to the result of cost-benefit analysis.(2)The mean cost efficiencies in these two production cycles are both at a high level as well,while the second cycle performs slightly more efficiently.Production systems have significant influence on cost efficiencies.The mean CE score of polyculture system is much lower than that of monoculture system,indicating monoculture system is more efficient and hence more competitive than that of polyculture system when measured by CE index.(3)The result of the SRPF model shows that output mixes have significant effects on the frontier output norm.The mean technical efficiencies in the surveyed two production cycles are both at a high level,while the second cycle performs slightly more efficiently.Production systems have significant influence on technical efficiencies.The mean TE score of polyculture system is much higher than that of monoculture system,indicating polyculture system is more efficient than monoculture system when measured by TE index.(4)Production systems have significant influences on resource efficiency and environment condition.The efficiency of feed utilization of monoculture system is significantly lower than that of polyculture system,indicating that polyculture system consumes less feedstuff and less high quality protein raw material in producing the same quantity of fish products.Production of anunonia nitrogen(TAN)per mu is much higher in ponds of practicing monoculture than practicing polyculture,revealing that monoculture ponds have polluted the environment more heavily when compared with polyculture ponds.The above conclusions have the policy implication of encouraging polycuture from the respective of production systems.As farmers always aim to maximize the benefits,it is most probable that they gain rapid development at the cost of the environment.The following suggestions may be taken in order to guide monoculture farmers or companies to switch their system to polyculture.(1)Speed up the implement of discharge standard for aquaculture pond effluent.As producers who practice monoculture usually do more harm to aquaculture water but at the least cost,it is indispensable to make them take their responsibilities for emission reduction and therefore help them make the system transiton.(2)The related extension departments in central and regional governments should support the transformation and upgrading of pond aquaculture industries through active measures,e.g.,formulating some special operational regulations on polyculture and encouraging researchers from colleges and institutes to provide on-the-spot technical supervision.(3)Government might implement a policy that rewards individuals or companies who extend polyculture activities,such as financial subsidies for both polyculture feedstuff and diversified species and insurance policy favors for ecological production systems.