Status Of Marine Fishery Resources Enhancement And Release In Shandong And The Primary Study Of SD Simulation

Fishery resources enhancement and release is a method which release cultured juveniles of fish, shrimp, crab, shellfish and etc. into the wild either for restocking or for enhancement of fishery biomass. Nowadays, the growing human population and increasing food demand have put pressure on coastal environments and fisheries resources. Over-fishing and destruction of coastal habitats have resulted in depletion of coastal resources. Long-distant fishery has been restricted by the 200 sea miles'demarcation of exclusive economic zone. Because of small risk investment, huge profit, and easy-management of stock enhancement industry, it has great potential for development.The measure of stock enhancement and release in China has been taken for over twenty years, which relates to a variety of species and different sea areas. According to the historic data and literature, this paper describes the development and status of fishery enhancement in China, especially in Shandong, including trends of released number, recapture rate, and the distribution of the main species released in different areas. By field survey and interview, it analyses the stock enhancement and release status of the shrimp Penaeus chinensis, Penaeus japonicus, jelly fish, and Cuttlefish in Shandong.According to the theory of system dynamics, this paper takes stock dynamic fluctuation, ecological environment and community capital into account, and constructs simulative model of stock enhancement, with system simulating software"Vensim". By taking shrimp enhancement in Shandong as an example, this paper analyses the fluctuation of fishery resource, feed biomass and capital,with an assumption that the releasing numbers is consistent each year. Simulative results shows that, fishery biomass and capital ascend along with the augment of releasing number, and gradually go to equilibrium, while the feed biomass fluctuates in a opposite way. Calculation will stop in this model when releasing number is larger than a certain scope, which means that the releasing performance exceed the carrying capacity of water area. In addition, this paper also analyses the fluctuation of the fishery biomass,recapture weight and capital with five different fishing efforts. The more fishing effort, the fewer fishery resource biomass and the more recapture weight and capital.Study of stock enhancement and release as a system project to give a qualitative and quantitative analysis is few. This paper attempts to have a primary study from the point of view of system dynamics, expecting to provide convenient and economic instrument for simulating test. The SD simulation of shrimp enhancement and release in Shandong shows that the simulating result is approximately consistent with the reality. By synthesis of the data, it is considered that 1 billion is the relatively suitable number for releasing shrimp in sea area of Shandong. Small releasing number cannot bring high profit, while too great releasing number will lead to unbalance of ecological system.The result of this study is expected to provide some useful advices for further policy-making in marine fishery resources enhancement program.