There are several reasons why some dolphin species are in the “Endangered Species” category according to the Red List of the International Union for the Conservation of Nature (IUCN). Among these are intentional killing for commercial purposes, increasing mortality produced by fishing materials abandoned at sea, either by entanglement or by ingestion of debris, ship traffic that causes noise pollution and injuries by contact, toxic contaminants and coastal development projects that disturb populations and damage marine ecosystems where they get their food.

Examples of species in danger of extinction are the Hector dolphin (Cephalorhynchus hectori) and the Ganges dolphin (Platanista gangetica). The baiji (Lipotes vexillifer) continues within the classification “Critically endangered, ” but most scientists believe that they are already extinct.