Obligate river dolphins occur only in the rivers of Asia and South America, where they are increasingly subject to damaging pressures such as habitat degradation, food competition and entanglement in fishing gear as human populations expand. The Amazon basin hosts two, very different, dolphins—the boto or Amazon river dolphin (Inia geoffrensis) and the smaller tucuxi (Sotalia fluviatilis). Both species have wide geographical ranges and were once considered to be relatively abundant.
