Freshwater cetaceans: the river dolphins of the world

A handful of cetaceans have left the sea for the world’s great rivers. These river dolphins of the Amazon, the Ganges, the Indus and the Yangtze are today among the most threatened mammals on the planet, and one of them, the baiji, has already gone.

Adapted to turbid water, they have developed extraordinary solutions: the flexible neck of the boto for threading through the flooded forest, near-total blindness and refined echolocation in the Ganges and Indus river dolphins, which swim on their side. The widget above details each species, its IUCN status and the threats that weigh on it.

Why are river dolphins so threatened?

River dolphins do not belong to a single family: they are the result of convergent evolution within distinct lineages (Iniidae for the boto, Platanistidae for the Ganges and Indus river dolphins, Lipotidae for the baiji, Phocoenidae for the Yangtze finless porpoise). Living in fresh water exposes them to cumulative threats: dams that fragment populations, bycatch in gillnets, pollution (mercury from gold panning, pesticides), river traffic and the fall in river flow linked to irrigation and climate change.

The disappearance of the baiji in 2006 remains the first documented case of a cetacean extinction caused by humans. Conversely, the recent rebound of the Yangtze finless porpoise (from 1,012 individuals in 2017 to 1,249 in 2022) proves that a determined conservation policy can reverse the trend.

Going further: see the conservation status by species, the current population figures and the map of the cetaceans of France. All our tools can be found in the interactive explorer.