Chinese white dolphin

The Indo-Pacific humpback dolphin (Sousa chinensis) is a species of humpback dolphin inhabiting coastal waters of the eastern Indian and western Pacific Oceans. This species is often referred to as the Chinese white dolphin in mainland China, Macau, Hong Kong, Singapore and Taiwan as a common name. Some biologists regard the Indo-Pacific dolphin as a subspecies of the Indian Ocean humpback dolphin (S. plumbea) which ranges from East Africa to India. However, DNA testing studies have shown that the two are distinct species. A new species, the Australian humpback dolphin (S. sahulensis), was split off from S. chinensis and recognized as a distinct species in 2014. Nevertheless, there are still several unresolved issues in differentiation of the Indian Ocean-type and Indo-Pacific-type humpback dolphins.

In Hong Kong, boat trips to visit the Indo-Pacific humpback dolphins have been running since the 1990s. The dolphins mainly live in the waters of Lantau North, Southeast Lantau, the Soko Islands and Peng Chau. A code of conduct regulates dolphin-watching activity in Hong Kong waters. There have been some reports of dolphin watching practices that have further endangered the Indo-Pacific humpback dolphins, such as in Sanniang Bay dolphin sanctuary in Qinzhou and off Xiamen. However, these generally are small, locally organised one-off tours or private pleasure boats that do not adhere to the Hong Kong Agricultural and Fisheries Department's voluntary code of conduct. Nánpēng Islands Marine Sanctuary in Nan'ao County is also home to local pods. The population in Leizhou Bay, Leizhou Peninsula, comprising nearly 1,000 animals and the second largest population in the nation, may also be targeted for future tourism. Hepu National Sanctuary of Dugongs, and waters around Sanya Bay and other coasts adjacent on Hainan Island are home to some dolphins. As the environment and local ecosystems recovery, dolphins' presences in nearby waters have been increasing such as vicinity to the nature sanctuary of Weizhou and Xieyang Islands. Gulf of Tonkin waters in Vietnam may have unstudied populations that may appear elsewhere such as along Xuân Thủy National Park and Hòn Dáu Island in Hải Phòng. Cambodia: In December 2023, the Marine Conservation Cambodia (MCC) estimated between 100 and 200 the number of Indo-Pacific humpback dolphins in the region of Kampot and Koh Kong. During a survey in May 2024, MCC observed a pod of humpback dolphins with an Irrawady dolphin mother and calf on the Prek Tnaot River in Kampot.

Indo-Pacific humpback dolphins live in small groups, generally with fewer than ten individuals. They hunt as a group using echolocation. Adult dolphins come to the water surface to breathe for 20 to 30 seconds before diving deep again, for two to eight minutes. Dolphin calves, with smaller lung capacities, surface twice as often as adults, staying underwater for one to three minutes. Adult dolphins rarely stay under water for more than four minutes. They sometimes leap completely out of the water. They may also rise up vertically from the water, exposing the dorsal half of their bodies. A pair of protruding eyes allows them to see clearly in both air and water.

Female dolphins reach sexual maturity at around ten years old, while males mature at around 13 years old. They usually mate from the end of summer to autumn, and calves are born after a gestation period of eleven months. The mother stays with her calf until it can find food for itself, usually when it reaches 3–4 years old.

Two subspecies of the Indo-Pacific humpback dolphin are currently recognized: S. c. chinensis, or the Chinese humpback dolphin S. c. taiwanensis, or the Taiwanese humpback dolphin An adult Indo-Pacific humpback dolphin is grey, white or pink and may appear as an albino dolphin to some. Populations along the coasts of China and Thailand have been observed with pink skin. The pink colour originates not from a pigment, but from blood vessels which were overdeveloped for thermoregulation. The body length is 2 to 3.5 m (6 ft 7 in to 11 ft 6 in) for adults, 1 m (3 ft 3 in) for infants. An adult weighs 150 to 230 kg (330 to 510 lb). Indo-Pacific humpback dolphins live up to 40 years, as determined by the analysis of their teeth. Calves are dark grey or black at birth and measure around 1 m (3.3 ft) in length. Their coloration lightens through a mottled grey as they age.

The Indo-Pacific humpback dolphin is threatened by habitat loss, water pollution, coastal development, overfishing and an increase in marine traffic within its range. In 2015, the Indo-Pacific humpback dolphin was classed as "vulnerable" on the IUCN Red List of Threatened Species.

The Indo-Pacific humpback dolphin is listed on Appendix II of the convention on the Conservation of Migratory Species of Wild Animals (CMS). It is listed on Appendix II as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements. In the interim of 2003–2013, the number of these dolphins in the bay around Hong Kong has dwindled from a population of 159 to just 61 individuals, a population decline of 60% in the last decade. The population continues to be further threatened by pollution, vessel collision, overfishing, and underwater noise pollution. In addition to their natural susceptibility to anthropogenic disturbances, the Chinese white dolphin's late sexual maturity, reduced fecundity, reduced calf survival, and long calving intervals heavily curtails their ability to naturally cope with elevated rates of mortality. In recent years, Taiwan launched the largest Indo-Pacific Humpbacked Dolphin sanctuary on the Taiwanese coast, stretching from Miaoli County to Chiayi County. The Indo-Pacific humpback dolphin is also covered by the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MoU).

Two subspecies of the Indo-Pacific humpback dolphin are currently recognized: S. c. chinensis, or the Chinese humpback dolphin S. c. taiwanensis, or the Taiwanese humpback dolphin