Indo-Pacific humpback dolphin / Indian Ocean humpback dolphin

Sousa chinensis / Sousa plumbea
Other names: 
  • Sousa
  • Chinese white dolphin
  • Indian Ocean dolphin
  • Pink dolphin
Maximum length: 
  • Male: 2.8m
  • Female: 2.6m
  • Calf: 1m
Maximum weight: 
  • Male: 280kg
  • Female: Unknown
  • Calf: Unknown
Diet: 
  • Fish (nearshore, estuarine and reef)
  • Squid
Estimated population: 
Unknown
IUCN Listing: 
Indo-Pacific VU (eastern Taiwan Strait subpopulation CR) / Indian Ocean EN
CITES Appendix: 
I
CMS Appendix: 
II
Classification: 

There have recently been changes to the number of species in this genus. In addition to the Atlantic humpback dolphin (Sousa teuszii), three species are now recognised; Sousa chinensis (Indo-Pacific humpback dolphin) – found from the east coast of India, through the Indo-Malay archipelago and east towards Australia; Sousa plumbea (Indian Ocean humpback dolphin) – found from South Africa to India; and Sousa sahulensis (Australian humpback dolphin) - found in northern Australia. One population of the Indo-Pacific humpback dolphin, living off the industrial west coast of Taiwan, has been recently recognised as a sub-species, S. c. taiwanensis and is rated Critically Endangered.

Appearance: 

As suggested by the name, in many parts of their range the Indo-Pacific humpback dolphin and the Indian Ocean humpback dolphin have a distinct hump at the base of the dorsal fin. Those in the easterly reaches of the species' distribution, lack this defining characteristic. The Indo-Pacific humpback dolphin is a medium sized, robust dolphin with a rounded melon that slopes down to the beak. The flippers are broad and rounded, and the beak is long and narrow. There is substantial morphological variation among differing species and populations, and colouration of these species ranges from white to pink to dark grey. In the western portion of their range (now classified as Indian Ocean humpback dolphins), calves are born a light grey colour and darken with age. Whereas in the eastern portion of their range (Indo-Pacific humpback dolphins) calves are born a dark grey and lighten with age. This transition from dark to light colouration results in the animals going through various stages of having dark spots and speckles around the body, all of which fade with age.

Behaviour: 

Humpback dolphins are coastal animals, venturing quite far landward into estuaries and mangroves. Their inshore habitats are often turbid waters and thus sound production and reception are crucial for navigation and social contact. In addition to their high frequency echolocation clicks, they are highly vocal, producing whistles and screams singly or in sequences and of varying lengths. They are not known to bowride very often, but they do breach, lobtail, and even somersault on occasion. They may also be seen sometimes swimming on one side while waving a flipper in the air. They are generally slow swimmers but sometimes will chase each other around in circles at high speed; researchers suggest this may be courtship behaviour. The average life-span of a humpback dolphin is thought to be approximately 40 years of age.

Distribution: 

The Indian Ocean humpback dolphin is known to occur within the Indian Ocean from South Africa to India. The Indo-Pacific humpback dolphin from india to the South China Sea although discrete populations of both species are thought to exist, for example in the Pearl River Estuary, the Persian Gulf and the coastal waters of eastern South Africa. Due to their preference for nearshore waters they are especially at risk from human activities. Bycatch in fishing gear is a serious threat, and many populations have been found to have dangerously high levels of contaminants, which may interfere with reproductive success. Industrial activities and coastal development continue to degrade their habitat and increasing ship and boat traffic is a serious concern for this species. The IUCN currently categorises the Indo-Pacific humpback dolphin as Vulnerable (2017) and the Indian Ocean humpback dolphin as Endangered (2017).

Distribution map: