Accelerating population decline of Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis)

The Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) is now the only cetacean species in the Yangtze River following the probable extinction of the baiji (Lipotes vexillifer). However, population abundance estimates and genetic diversity studies both indicate that the porpoise population is declining and may also become extinct in the wild in the near future. We used data from 279 stranded porpoises that were collected along the middle and lower reaches of the Yangtze River since 1978 to construct life tables for the porpoise population before and after 1993. Demographic rate estimates reveal an accelerating decline of the Yangtze porpoise population according to the instantaneous rate of increase ( r ¯ ), from r ¯ = - 0.0159 (SD = 0.0135) to r ¯ = - 0.0625 (SD = 0.0169). Using an individual-based Leslie matrix model, there is a high probability of extinction (86.06%) within the next 100 years. Effective conservation measures must be enacted immediately. The pattern of cetacean decline and extinction in the Yangtze provides a startling demonstration of how rapid economic development without adequate environmental control leads to deterioration of natural habitats and threatens native species extremely rapid. This research also emphasizes the need for precautionary conservation action in other riverine systems containing freshwater cetacean species.