Internal cause: the reproductive ability of baiji dolphin is low, 6-8 years old, with one fetus and one offspring, and the reproductive cycle of mature females is about 2 years.
Single feeding habit, only eating fish of a certain size; It is speculated that its ability is relatively low (relative to finless porpoise). These are the internal factors that cause the endangered population of Baiji dolphin (Feng et al. 1986).
External factors: ① overfishing: on the one hand, it destroyed the fish resources on which the baiji depended; On the other hand, some harmful fishing gear and fishing method, such as rolling hook, electric fish, fried fish, poisonous fish, etc., can directly harm baiji; (2) The rapid development of shipping industry: On the one hand, a large number of motorboats occupy the limited living space of Baiji dolphin, and the loud noise from motorboats interferes with the sonar system of Baiji dolphin; On the other hand, the propeller can directly kill the baiji; (3) Construction of water conservancy facilities: The construction of dams and culverts for flood control and drainage in the Yangtze River has changed the environment of Tongjiang in lakes and small tributaries along the Yangtze River in the past, resulting in the loss or deterioration of the habitat of baiji. The indirect impact of giant water conservancy projects such as Gezhouba and Three Gorges Dam on baiji can not be ignored; ④ Water pollution in the Yangtze River: The water quality in the coastal zone near the main stream of the Yangtze River and below Nanjing has been polluted to some extent, and certain concentrations of organochlorine and heavy metals have been detected in baiji and finless porpoise. In addition, the capsizing accident of pesticide transport vehicles and ships in the Yangtze River and its vicinity will also bring disastrous consequences to fish and baiji in the Yangtze River.