Indo-Pacific humpback dolphin

Appearance

An adult Indo-Pacific humpback dolphin is gray, white or pink and may appear as an albino dolphin to some. Uniquely, the population along the Chinese coast has pink skin, and 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 for adults 1 m for infants. An adult weighs 150 to 230 kg . Indo-Pacific humpback dolphins live up to 40 years, as determined by the analysis of their teeth.

At birth, the dolphins are black. They change to grey, then pinkish with spots when young. Adults are gray, white or pink.

Distribution

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.

Status

The Indo-Pacific humpback dolphin is listed on Appendix II of the Convention on the Conservation of Migratory Species of Wild Animals . 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.

China has launched the largest Indo-Pacific Humpbacked Dolphin sanctuary on Taiwanese coasts. 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 .

Behavior

Indo-Pacific humpback 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.

Habitat

The Indo-Pacific humpback dolphin is threatened by both habitat loss and pollution. Conservationists warn that Hong Kong may lose its rare Indo-Pacific humpback dolphins, also known as pink dolphins for their unique colour, unless China takes urgent action against pollution and other threats. Their numbers in Hong Kong waters have fallen from an estimated 158 in 2003 to just 78 in 2011, with a further decline expected by the Hong Kong Dolphin Conservation Society. A tour guide from Hong Kong Dolphinwatch spotted a group of pink dolphins helping a mother support the body of her dead calf above the water in an attempt to revive it. The scene, captured on video and widely shared on Facebook, has raised fresh concerns about the dwindling population in a city where dolphin watching is a tourist attraction. "We’re 99 percent certain the calf died from toxins in the mother’s milk, accumulated from polluted seawater," said Hong Kong Dolphinwatch spokeswoman Janet Walker, who added it was the third such incident reported in April alone. Fewer than 2,500 of the mammals survive in the Pearl River Delta, the body of water between Macau and Hong Kong, with the majority found in Chinese waters and the rest in Hong Kong.

Reproduction

Indo-Pacific humpback dolphins are sociable creatures and live in groups of three to four. Female dolphins become mature at 10 years old, while the males become mature at 13 years old. They usually mate from the end of summer to autumn. Infant dolphins are usually born 11 months after the mating. Mature females can give birth every three years, and parental care lasts until their offspring can find food themselves.

History and timeline

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⤷  1637: The Indo-Pacific humpback dolphin was first documented in English by the adventurer Peter Mundy in Hong Kong near the Pearl River. The species are attracted to the Pearl River Estuary because of its brackish waters.
⤷  1765: Pehr Osbeck gives the first scientific description of the species.
⤷  Late 1980s: Environmentalists started to pay attention to the Indo-Pacific humpback dolphin population.
⤷  Early 1990: The Hong Kong public started to become aware of the Indo-Pacific humpback dolphin. This was due to the side effects of the construction of the Chek Lap Kok Airport. It was one of the world's largest single reclamation projects: the reclamation of nine square kilometers of the seabed near Northern Lantau, which was one of the major habitats of the dolphins.
⤷  Early 1993: Re-evaluation of the environmental effects of the construction of Chek Lap Kok Airport. This alerted eco-activists such as those from the World Wide Fund for Nature in Hong Kong, in turn bringing media attention on the matter. Soon enough, the Hong Kong Government began getting involved by funding projects to research on the Indo-Pacific humpback dolphins
⤷  Late 1993: The Agriculture, Fisheries and Conservation Department was founded.
⤷  1996: Dr. Thomas Jefferson began to conduct research on the Indo-Pacific humpback dolphins in hope of discovering more about them.
⤷  1997: The Indo-Pacific humpback dolphin became the official mascot of the 1997 sovereignty changing ceremonies in Hong Kong.
⤷  1998: The research results of Dr. Thomas Jefferson was published in "Wildlife Monographs".
⤷  1998: The Hong Kong Dolphinwatch was organized and began to run dolphin watching tours for the general public to raise the public's awareness of the species.
⤷  2000: The Agriculture, Fisheries and Conservation Department started to conduct long-term observation of the Indo-Pacific humpback dolphins in Hong Kong.
⤷  2000: The population of Indo-Pacific humpback dolphins has reached around 80–140 dolphins in the Pearl River waters.
⤷  2014: Dr. Thomas Jefferson and Dr. Howard C. Rosenbaum revised the taxonomy of the humpback dolphins . They describe a new species, the Australian humpback dolphin and define the accepted common name for this species, the Indo-Pacific Humpback dolphin.