The Irrawaddy dolphin (Orcaella brevirostris) is a fascinating species of oceanic dolphin that is found in scattered subpopulations near sea coasts, estuaries, and rivers in parts of the Bay of Bengal and Southeast Asia. With its slate blue to slate gray color and rounded forehead, it closely resembles the Australian snubfin dolphin, which was not described as a separate species until 2005.
Despite being found in much of the riverine and marine zones of South and Southeast Asia, the Irrawaddy dolphin is known for having concentrated populations in only a few lagoons. The most notable of these are found in Chilika Lake in Odisha, India, and Songkhla Lake in southern Thailand.
The Irrawaddy dolphin's name comes from the Irrawaddy River in Myanmar, where it was first discovered. It is also found in other major river systems in the region, including the Mekong, Mahakam, and Ayeyarwady Rivers. This makes it a highly adaptable species, capable of thriving in both saltwater and freshwater environments, and is what makes it a euryhaline species.
One of the most remarkable features of the Irrawaddy dolphin is its ability to catch fish using a unique hunting technique known as "cooperative fishing." This involves the dolphins working together with local fishermen to corral fish into shallow waters, where they can be easily caught. The dolphins benefit from this relationship by feeding on the fish that escape the fishermen's nets.
Unfortunately, the Irrawaddy dolphin is considered a vulnerable species, with only an estimated 7,500 individuals remaining in the wild. Its populations have been greatly impacted by habitat loss, water pollution, accidental entanglement in fishing nets, and overfishing of its prey species.
Conservation efforts are underway to protect this remarkable species. In Chilika Lake, for example, the government of Odisha has established a protected area for the dolphins, which includes a ban on fishing in certain parts of the lake. In Thailand, the government has implemented similar measures to protect the dolphins in Songkhla Lake.
In conclusion, the Irrawaddy dolphin is a unique and fascinating species of oceanic dolphin that is found in scattered subpopulations in parts of the Bay of Bengal and Southeast Asia. Its ability to thrive in both saltwater and freshwater environments and its cooperative fishing technique with humans make it an important and culturally significant species. However, its populations are under threat, and it is essential that conservation efforts continue to protect this vulnerable species for future generations to enjoy.