The authors assessed more than 340,000 km of river, combining river connectivity status with species occurrence models to map freshwater connectivity corridors. The assessment focused on long-distance migratory fishes and turtles with migrations over 500 km, and on river dolphins.
In 2019, 16 of 26 very long rivers over 1,000 km were free-flowing, but only 9 would remain so if all proposed dams were built. Under that scenario, 18 of 93 long and very long corridors would lose their status, including the Amazon, Negro, Marañón, Napo, Ucayali, Beni and Uraricoera rivers.