**2.1 Irrawaddy dolphin**

This dolphin name comes from the Irrawaddy River, Myanmar and endangered species among all cetacean species in the world. Its scientific name is *Orcaella brevirostris* and its local name is the Iraboti dolphin. This dolphin is considered Vulnerable globally and Near Threatened in Bangladesh due to anthropogenic activities. Irrawaddy dolphins are critically endangered. Species color is gray to dark slate blue, paler underneath, rounded, and small dorsal fin present; the flipper is rounded and wide. About 451 individual Irrawaddy dolphins were sighted near the coastal water of Sundarbans mangrove forest [12]. This dolphin is very similar to the finless porpoise and fishes, crustaceans, and invertebrates are main food [13]. In the coastal region, they are more limited although survive around South and Southeast Asia. According to Smith et al. [14] the 779.7 km of trackline and a 16,779 km<sup>2</sup> study

*Perspective Chapter: Status of Dolphin in the Maritime Area of Bangladesh DOI: http://dx.doi.org/10.5772/intechopen.102022*

**Figure 2.**

*Different types of dolphin occurred in the maritime area of Bangladesh. (1) Irrawaddy dolphin, (2) Indo-Pacific Humpback dolphin, (3) Indo-Pacific Bottlenose dolphin, (4) Spotted dolphin, (5) Spinner dolphin, and (6) Ganges river dolphin.*

area were investigated, an abundance of Irrawaddy dolphin was assessed 5383 (CV = 39.5%) in the maritime water in Bangladesh including number (n) was 75, mean group size was 2.2, SD 1.8, dolphin range was 1–10. Also, large populations of Irrawaddy dolphins were recorded in the marine coastal water of Bangladesh. The reported number of Irrawaddy dolphins 114 from 2004 to 2014 [15] and UNDP Bangladesh [16] also stated a total number of 451, respectively in the Sundarban mangrove region of Bangladesh in **Figure 3**. Smith et al. [12] reported the encounter rate of dolphins as 0.19 in the Sundarban area, Bangladesh whereas a similar encounter of 0.16 showed at the Ayeyarwady River in Myanmar [17]. The Sundarbans and their adjacent areas are major and hotspot areas for the Irrawaddy Dolphin and half of the population are present in the maritime area of Bangladesh. Based on IUCN Red List in Bangladesh and India, this species is Vulnerable, but Critically Endangered species in Laos, Myanmar, Malaysia, Thailand, and Philippines.

#### **2.2 Indo-Pacific Humpback dolphin**

The Indo-Pacific humpback dolphin has been recorded in the marine water of Bangladesh and also sighted near the eastern India region [18]. This species scientific name is *Sousa chinensis* and its local name is Golapi dolphin. The highest size recorded

#### **Figure 3.**

*Number of species sighted in the maritime water of Bangladesh.*

280 cm, healthy body, and extended beak. Color outline differs with age and area. Color show bluish gray to light cream or pink. This dolphin shape is very similar with the bottlenose dolphin. Color, dorsal fin, and head size separate them. Humpback dolphin usually swims in groups. They are survived in the tropics and subtropics area of coastal water and small fishes are major food. The marine water environment of Southeast Asia is a significant habitat for this dolphin but this species population, distribution, abundance, and feature of habitat very little study has been done to ensure survival species [19–21]. World Conservation Society [9] remarks the area about 327 km2 of importance habitat for humpback dolphins encompassing 73% of sightings in coastal waters near the mangrove forest. Also, at the 24.73°–24.33°N geographic site, this dolphin sighting per unit effort was 3.88 [22, 23]. WCS was assessed humpback dolphins survive in shallow water and coastal waters in the Bay of Bengal but most of the species occur in the northern Indian and eastern Pacific oceans. According to the IUCN Red List this species is Near Threatened but presently like remark as vulnerable. Most of the humpback dolphins swim in the marine protected area (MPA).
