Threats
The finless porpoise's preference for coastal and riverine habitats makes it highly vulnerable to the impacts of human activities that take place in these regions (2). Although the finless porpoise is not directly targeted by fishermen, large numbers die when they become entangled in fishing nets, particularly gillnets (2) (5). Electric fishing also threatens the finless porpoise in the Yangtze River; despite being illegal, this destructive fishing method has become widespread in the river system during the last decade, not only killing some porpoises outright but also depleting their prey (5). Furthermore, high levels of toxic pollutants have been reported from Japanese finless porpoises, and while finless porpoises tend to avoid boats (2), mortalities caused by collisions with vessels may be a problem in busy shipping areas, such as Hong Kong (5). The deforestation of mangrove areas, rampant harbour expansion and the development of shrimp farms is taking place throughout Asia, degrading the porpoises' coastal habitat (2) (5). The Yangtze River finless porpoise is particularly vulnerable to habitat degradation, with the river not only being impacted by fishing and pollution, but also by the numerous dams that dot the Yangtze River basin (5). The impact that these threats may have on the Yangtze finless porpoise is illustrated only too well by the recent tragic demise of the baiji (Lipotes vexillifer), which was believed to have gone extinct from the Yangtze River in 2006 (6).
