Indo-Pacific humpback dolphin: where and when to see them

The Indo-Pacific humpback dolphin is a shallow-water coastal species found in parts of the eastern Indian and western Pacific oceans. In Thailand it occurs locally, especially in suitable Gulf coastal habitats. Colour varies with age and population, and some adults become strikingly pale or pinkish. Its dependence on nearshore waters exposes it to fishing gear, vessel traffic, pollution and construction, so seemingly accessible habitat may also be heavily threatened.

Size

2–2.8 m long

Weight

150–280 kg

Lifespan

30–40 years

Status

Vulnerable

These dolphins usually travel in small, changing groups and often surface with an unhurried rolling movement. They hunt around estuaries, shoals and other places where fish concentrate. Social interactions can include body contact and occasional leaps, but quiet movement is more typical than prolonged display. Mothers maintain close relationships with calves. Individuals may repeatedly use particular stretches of coast, bringing their daily activities into contact with fisheries and boat traffic. These dolphins often engage in 'spyhopping' to survey their surroundings above the water. Their interactions with coastal communities are frequent, necessitating careful management to reduce human induced impacts.

• Calves are generally darker than pale adults in populations that lose pigmentation with age.
• A pink appearance can reflect blood circulation close to the skin rather than pink pigment.
• The name Chinese white dolphin is also used for this species.
• Modern taxonomy separates it from the Indian Ocean and Australian humpback dolphins.

Local animals may occur throughout the year, but calm conditions make distant shore observation more practical. Weather patterns differ around Thailand's coasts. For Gulf locations, select a locally suitable travel window without treating it as a breeding season or guaranteed dolphin peak. While present year-round, the dry season (typically November to April) often offers calmer seas, improving visibility for boat-based viewing. Always check local weather forecasts as conditions can vary significantly by region and time of year.

Estuaries, shallow bays, mangrove-fringed coasts and nearshore waters over soft substrates are characteristic habitats. The species is marine, although it can enter brackish estuarine water. Thai populations are localised, and records from one coastal district should not be extrapolated nationwide. They are highly philopatric, often restricting their movements to small home ranges along coastlines. Their presence is a good indicator of healthy coastal ecosystems, including mangrove forests and seagrass beds.

The diet consists chiefly of coastal fish, including species associated with estuaries and the seabed. Dolphins use echolocation while searching in frequently turbid water. Feeding around fishing activity can increase exposure to entanglement and does not justify deliberate provisioning by observers. They opportunistically feed on a variety of coastal fish and cephalopods, often associated with sandy or muddy bottoms. This adaptable foraging behavior helps them thrive in diverse estuarine and nearshore environments.

Common name

Indo-Pacific humpback dolphin

Scientific name

Sousa chinensis

Animal group

Marine life

Size

2–2.8 m long

Weight

150–280 kg

Lifespan

30–40 years

Status

Vulnerable

Identification

Compared with bottlenose dolphins, it has a longer slender beak and a smaller dorsal fin on a raised base, while pale adults are unlike the typically darker Indian Ocean humpback dolphin. Adults in Thai waters frequently exhibit a striking pinkish coloration, which intensifies with age due to blood vessel distribution under their pale skin. Calves are typically a darker gray, gradually lightening as they mature.