Difference between the WTP and WTA in cultural service value evaluation of agriculture ecosystems: Shanghai pond aquaculture case study

Pond aquaculture has existed in China for thousands of years and has been not only a major source of food, but also provided cultural service. The development of service industry in agriculture has further highlighted the value of pond aquaculture. The Contingent Valuation Method (CVM), one of several methods for evaluating non-market values, has been widely used data analysis. However, there has remained much controversy on the effectiveness and stability of CVM. One such hot spot of discussion has been strategic bias, a significant disparity between willingness to pay (WTP) and willingness to accept (WTA), in evaluation of environment products and services values. Current literature has shown that few researches exist on the evaluation of cultural service values of aquaculture ecosystems. This paper used pond aquaculture in Qingpu, Jiading and Fengxian Districts of Shanghai to evaluate the cultural services values and discuss the difference between WTP and WTA as given by Tobit and Mulit-Logit models. The results showed that WTP was affected by the income, education, interest and satisfaction with pond environments of the interviewees. A significant positive relationship existed between WTP and the above factors. WTA was also influenced by income and satisfaction with pond environments. WTA was significantly positively related to income. But satisfaction with pond environment was negatively related to both WTP and WTA. Household income, register, age and interest in pond activities of interviewee were the main influence factors on WTA/WTP asymmetry. The average WTA/WTP ratio was 5︰1. Income, substitution, endowment and prospect effects as well as property right affected the differences between WTP and WTA. Due to deviations in interviewees' understandings of WTA, responses were higher than the real pond value. Based on this fact, WTP was used as the preferred assessment method. The average value of WTP of the investigated area was 163.75 Yuan per person. Then based on the population statistical yearbook, total cultural services values of Qingpu, Jading and Fengxian were 177.161, 241.040 and 177.521 million Yuan per year, respectively. It suggested that in the construction of new rural areas in Shanghai, sufficient attention needed to be paid on the full play of cultural services values of aquaculture pond ecosystems. Functional departments needed to achieve full protection and sustainable utilization of ponds, with focus on increased farmer income.