Sangsuree Songtong, chief of Trat Marine National Park Operation Centre 4, said the dolphins were possibly hunting for food in the area.
The Irrawaddy dolphin (Orcaella brevirostris) is a species of oceanic dolphin found in scattered subpopulations near sea coasts and in estuaries and rivers in parts of the Bay of Bengal and Southeast Asia.
Although found in much of the riverine and marine zones of South and Southeast Asia, the only concentrated populations are in Chilika Lake in the Indian state of Odisha and in Songkhla Lake in southern Thailand.
Some Irrawaddy dolphin sub-populations are classified by the International Union for Conservation of Nature (IUCN) as critically endangered, such as in Laos, Cambodia, Vietnam (Mekong River), Indonesia (Mahakam River, Borneo), Myanmar (Ayeyarwady/Irrawaddy River), the Philippines (Malampaya Sound), and Thailand (Songkhla Lake).
In 2004, the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) shifted the Irrawaddy dolphin from Appendix II to Appendix I, which forbids all commercial trade in species that are threatened with extinction.