‘Red list’: All freshwater dolphins endangered But European bison numbers have improved By JAMES BROOKS and JAMEY KEATEN, Associated Press Published: December 15, 2020, 6:00am Share: 5 Photos A report published by International Union for Conservation of Nature highlights that all four known freshwater dolphin species, including the tucuxi dolphin in the Amazon River system, are now threatened with extinction. (Fernando Trujillo /International Union for Conservation of Nature) Photo Gallery GENEVA — A leading conservation group uniting governments and civil society says all four known freshwater dolphin species are now threatened with extinction, after newly discovered information on the tucuxi in the Amazon River system showed it too is endangered.