南海北部大陆架海洋生态系统Ecosim模型的动态模拟

为了确定最佳的渔业政策,采用EwE 5.1软件,对南海北部大陆架海洋生态系统构建了1987-1998年Ecosim(时间动态)模型。Ecosim模型包含了32个功能组,初始参数来源于20世纪80年代末期静态平衡的Ecopath模型。通过营养关系,分析了渔业捕捞对主要经济鱼类的动态影响。结果显示1998年系统总输出、总生物量都有不同程度的增加,而总捕捞量则有所降低;强化的捕捞压力导致了低值小型鱼类被捕食压力的间接缓解,大中型高价值鱼类的生物量发生明显下降;说明了生态系统呈现出逆向发育的主要原因在于过度捕捞所产生的从上而下(top-down)的控制作用。

Simulation of the Time Dynamics of Marine Ecosystems in the Northern Continental Shelf of South China Sea with Ecosim Model

A Ecosim model for the northern continental shelf of South China Sea is established for the period of 1987 to 1998 by using the EwE 5.1 software to examine the time dynamic change in the marine ecosystems.The model consists of 20 functional groups,with key initial parameters inherited from the mass-balanced Ecopath model in the late 1980s.The effects of fishing on the dominant economic fish species are examined through trophic interactions.The results show that total system throughput and total biomass increase to some extend,but total catches decline clearly in 1998.Intensified fishing pressure on economic fish species results in indirect "prey release" of some low-valued species of small fish,and as a consequence a decline in the biomass of many high-valued species of big(or middle) fish.The marine ecosystem appears to develop reversely,which was mainly attributed to top-down control exerted by overfishing.