This species is common, found in diverse habitats and widely distributed throughout Bangladesh. It does not fulfill any of the criteria to qualify threatened categories.

There is doubtful occurrence of this species in Bangladesh. Some literatures (Khan 1982, 2001, Sarker and Sarker 1988, 2005, Bates and Harrison 1997, Molur et al. 2002) mentioned the presence of this species in Bangladesh without any locality information and also without any scientific evidence. However, this species has been known to found in Bangladesh based on bat samples received from the Sundarbans (Blyth 1848). Therefore, it is categorized as Data Deficient.

The species is known from only one locality in Bangladesh, but is likely to occur in other localities of the country. A group of about 50 were seen roosting during the day, for at least several days, in a crevice of a building in Jahangirnagar University, Savar, Dhaka, in January 1995. A specimen was collected on 27 January 1995 and was identified as a free-tailed Bat, but the species-level identification could not be done at that time. The preserved specimen was re-examined in 2015 and was identified as Chaerephon plicatus, which is a new species for Bangladesh (M.M.H. Khan pers. obs.). The roosting colony disappeared after January 1995, indicating that it is not a resident in the area. The species is likely to occur in other areas of Bangladesh. There is not enough data to assess its status in Bangladesh. Therefore, it is listed as Data Deficient.

A population of 2,239 individuals of Tursiops aduncus has been estimated by Mansur et al. 2011 in the northern tip of Swatch of No-ground in the Bay of Bengal and there were also few sightings recorded outside of Swtach of No ground in the Bay of Bengal. Both the Extent of Occurrence and Area of Occupancy were much larger than the thresholds level of threatened categories. Moreover, no decline in the species population was found. Thus, it has been categorized as Least Concern.

Only one sighting of two individuals of Steno bredanesis in the Swatch of No-ground (165 km offshore on the south from the Sundarbans) was observed by BCDP in 2012 (BCDP Unpubl.). No more information is available to assess this species. Thus, it is categorized as Data Deficient.

Little is known about the distribution and population size of Stenella longirostris in Bangladesh. Fourteen sightings Stenella longirostris in the northern tip of Swatch of No-ground were reported by BCDP (2008) with mean group size 85. There was no more information available from other marine waters of the Bay of Bengal in Bangladesh territory. Thus it is categorized as Data Deficient.

Not much is known about the distribution and population size of Stenella attenuata in Bangladesh. A large group of about 800 individuals were in the far offshore of the southeast coast was reported by Smith et al. (2008) and eight sightings with mean group size of 137 individuals (range=20-350) were recorded in the Swatch of No-ground by BCDP (2008). This study does not cover the whole area of the Bay of Bengal, so this implies that significant number of population may occur further offshore in unsurveyed area. The Extent of Occurrence and the Area of Occupancy are much larger than the thresholds level of the threatened categories. Moreover, it is not believed to be facing any critical threat in the marine waters of Bangladesh (BCDP 2008). Thus, the species has been assessed as Least Concern.

In 2002, a single group of Indo-Pacific Humpback Dolphins (Sousa chinensis) was reported by Smith et al. (2006) in a relatively high salinity channel of the southwest portion of the Sundarbans Mangrove Forest of Bangladesh. A total of six sightings of Sousa chinensis (mean group size 16.2, range 2 - 55) in the nearshore water of the Bay of Bengal was documented in 2004 (Smith et al. 2008). A single sighting of two individuals was made in the outer mouth of Naaf river in the southeast of Bangladesh in 2007. The Extent of Occurrence and Area of Occupancy are greater than threshold level of threatened categories. There was no information on habitat decline. Thus, this species has been categorized as Least Concern.

There are only two sightings of Pseudorca crassidens have been reported: first one with about 30 individuals in the Swatch of No-ground in 2011, and second one with about 40 individuals in the offshore south of S. Martin's Island in 2012. One carcass was reported in the Daily Azadi newspaper of Chittagong on 28 December, 2010. There is no information available on its population size, threats or population trend. Thus, the species has been assessed as Data Deficient.

Throughout the distribution range, this species is facing a high risk of human impact, destruction of natural forests and daming of upper reaches of all trans-boundary rivers in the neighbouring countries that is causing massive siltation in all floodplain rivers. There has been a dramatic decline in the Extent of Occurrence, as well as habitat quality, especially in the Ganges (IWC, 2000) and Brahmaputra River basins, which is related to the construction of barrages in the upstream countries (M A R Khan pers. comm). The species has also disappeared from most of the tributaries of GangesBrahmaputra-Meghna river systems due to siltation, insufficient water flow. So, it is now restricted to a few larger channels (pers. obs.). It is assuming that at least 30% decline of population has occurred during last three generations with the decline in its habitat and incidental catch in drag net. Based on the ongoing threats, fragmentation of the population, the species has been assessed as Vulnerable.