Abstract:The Yangtze finless porpoise( Neophocaena phocaenoides asiaeorientalis )has a relatively isolated population and is a subspecies. Its population size is going down because of human impacts. Its population viability is analyzed by a simulation model VORTEX 7 3 on the basis of author′s past field researches and data from other researchers. The population dynamics of next 100 years is simulated. The population extinction probabilities are compared in assumed different conditions, such as environmental vari...