**1. Introduction**

Among the cetacean, the dolphin is the common name of aquatic mammals. Over the last decades, aquatic mammal conservation is a global concern due to human anthropogenic activities and rapidly declining the biodiversity. Losses of aquatic mammals or biodiversity directly affect on ecosystem locally or internationally that concerned by the Convention of Biological Diversity (CBD) in 1992. Marine mammal conservation is continuing process which cannot ever be well-thought-out completely in south Asia. In the Bay of Bengal, Swatch of No-ground has been established as Marine Protected Area (MPA) for biological species. As a big delta basin Ganges, Brahmaputra, and Meghna river systems are present along with the coastal regions in Bangladesh. IUCN Bangladesh [1] reported 10 cetacean species are present in the aquatic ecosystem of Bangladesh include the Ganges river dolphin. All marine dolphins are included in the Family Delphinidae. The very little study occurred on

the dolphins in the maritime area of Bangladesh, except some reports of species events [2–8]. According to WCS [9] about 1738 km2 areas are considered as a marine protected area (MPA) for marine mammal species, and MPA is constructed at the Northwest and Southeast geographic area of Bangladesh that is recognized with the Indian Ocean in **Figure 1**.

However, some author little studies completed on dolphins [7–12] but the status of dolphin investigation is not sufficient in the maritime area of Bangladesh due to lack of funds, strategic plan, and awareness. Although, False Killer whale, Bryde's whale, and Sperm whales are found in the marine water but different types of dolphins are survived in maritime areas of Bangladesh.
