Technical efficiency of carp polyculture production in Jiangsu, China: a ray stochastic frontier production approach

This study aims to examine the technical efficiency of crucian carp polyculture systems in Jiangsu province, China, applying stochastic frontier analysis. Prior aquaculture polyculture studies using this method neglected the multi-output nature of polyculture and aggregated all of the outputs into a single index. In this paper, we use a ray production function and adopt it in the stochastic frontier framework. Production functions defined as Cobb-Douglas and Translog specifications are both employed to compare cross-sectional data collected for 144 farmers in 2012. The results reveal that the Translog specification captures the production behaviour and that there is an evident technical inefficiency in the polyculture setting. The mean technical efficiency is 79%. The farms that applied the new polyculture system demonstrate significantly greater efficiency on average than farms that applied the traditional polyculture system. The output elasticity with respect to the polar coordinate angle theta(1) is calculated to be 0.17. This represents a 0.17% increase in the output norm with a 1% increase in the output mix with fixed proportions between crucian carp and filter-feeding fish. The output elasticity with respect to the polar coordinate angle theta(2) is -0.26. This represents a 0.26% decrease in the output norm due to a 1% increase in the output mix with the level of grass carp held constant. Hence, decision makers should be informed that the adopting of new species to the traditional system may be an effective way to unlock the productive potential of pond aquaculture in Jiangsu province.