Irrawaddy Dolphin

The small, beakless Irrawaddy dolphin frequents large rivers, estuaries, and freshwater lagoons in South and Southeast Asia. The Irrawaddy range extends from the Bay of Bengal to the Philippines and Papua New Guinea. Gray to dark slate blue in color, the dolphin has a rounded head and measures up to eight feet in length. Irrawaddy dolphins live in small groups of generally six or fewer, but sometimes as many as 15 individuals. They subsist on a diet of fish, and communicate with clicks, creaks, and buzzes. In a section of Myanmar’s Irrawaddy River, the dolphins are known to fish cooperatively with humans, herding fish schools toward the fishermen where they are easily caught in cast nets. The practice benefits the fishermen—increasing the size of their catches up to threefold—as well as the dolphins, which fill their own stomachs on the cornered fish and those that fall out of the fishing nets. Like several other species of dolphins and porpoises in South and Southeast Asia, Irrawaddy dolphins are disappearing at a rapid rate. However, there are some hopeful signs. Recently, WCS researchers found nearly 6,000 Irrawaddy dolphins swimming in the Sundarbans mangrove forest of Bangladesh and adjacent waters of the Bay of Bengal. Previously, the largest known populations of the dolphin had numbered in the low hundreds. Conservation of this enigmatic mammal, which lives in both river and marine environments, will depend on devising and implementing sound solutions for replacing harmful fishing practices and halting or mitigating the impacts of habitat loss.