| 论文摘要： |
Two species of cetaceans are endemic to the Yangtze River, the baiji or Yangtze River dolphin Lipotes vexillifer and the Yangtze finless porpoise Neophocaena asiaeorientalis asiaeorientalis. Over the past several decades, both species have suffered dramatic declines in abundance and concomitant reductions in the extent of their geographic ranges. In 2006, the baiji was presumed to be extinct when an extensive survey of the Yangtie River failed to find any evidence of its continued existence. Data from that same survey further indicated that the population size of the Yangtze finless porpoises had decreased from 2,700 in 1991 to approximately 1,800 individuals by 2006. Results of a more recent population survey of the Yangtze River conducted in 2012 revealed that this rapid decline has continued, with only approximately 1,000 Yangtze finless porpoises remaining across their former range. The population viability of both species is threatened primarily by overfishing and illegal fishing of their prey, heavy boating traffic, sand dredging, construction projects in or near the water, and pollution throughout the Yangtze River ecosystem. In an attempt to protect these species, several conservation strategies, including in situ conservation (i.e., on-site conservation), ex situ conservation (i.e., off-site conservation), and captive breeding programs have been implemented. In this review, we examine the effectiveness of these conservation strategies over the past three decades and synthesize these findings to make recommendations for the future protection of the Yangtze finless porpoise. |
