Prospects for the survival of Hong Kong's pink dolphins aren't looking too rosy.
Its famous Chinese white dolphins — popularly known as pink dolphins due to the bright pink hue many individuals exhibit later in life — are quickly disappearing from the city's waters due to an onslaught of human disturbances.
In 2005 there were 158 individuals living in Hong Kong's harbor area. Today there are 60 known individuals, according to a report by the Hong Kong Cetacean Research Project.
The dolphins have lived throughout the Pearl River Estuary for some 400 years and now make their home, more narrowly, in the western parts of Hong Kong's Lantau Island, where they've become a major tourist attraction.
The dolphins are born black and gradually change color to grey then later to white. Some dolphins turn a bright shade of pink instead due to the presence of blood vessels close to the skin that help cool the animals.
"There is actually a lot of color variation among Chinese white dolphins based on their age, sex, or geographic location," said Lisa Ballance, Director of NOAA's Marine Mammal and Turtle Research Division at the Southwest Fisheries Science Center in La Jolla, California. "So some dolphins are more pink than others and the adaptive significance of the color remains unclear."
The dolphins are members of the species of Indo-Pacific humpback dolphin, which live throughout the Indo-Pacific Region, the majority in coastal, estuarine environments.
Though the Indo-Pacific humpback dolphin is not a threatened species, there is a risk of local extinction for several of its populations, including those dwelling in Hong Kong and in the eastern Taiwan strait, according to Samuel Hung, Chairman of the Hong Kong Dolphin Conservation Society.
The dolphins face a steady stream of threats, among them bridge construction, water pollution, and lack of prey due to overfishing. High concentrations of environmental contaminants have been found in the bodies of dead dolphins, according Hung.
"[The dolphins] used to occur regularly in the northern and western waters of Lantau Island, and seasonally in the southern waters," Hunt said. "However, due to the construction of the [Hong Kong-Macau] bridge and other existing threats, the usage of northern waters have been reduced dramatically in the past several years."
Ferryboats are also a serious threat to the dolphins. A 2011 report conducted by the World Wildlife Fund in Hong Kong pointed to city's high-speed ferryboat traffic, which increased 48 percent between 1999 and 2010.
Samantha Lee, WWF-Hong Kong's assistant conservation manager, said in November, "Every day the marine animals have to doge high-speed ferries and construction barges, detour construction sites of the Hong Kong-Zuhai-Macao Bridge while putting up with noise and water pollution."
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The dolphin population isn't simply declining because some dolphins are dying. Hung said that some individuals have moved into Chinese waters, while others remain in Hong Kong but have been less successful at reproducing due to the disruption to their habitat.
Several ongoing construction projects also contribute to the decimation of the dolphins' habitat, most notably the construction of a new runway at Hong Kong's international airport, which could disturb 1,600 acres of seabed that the Chinese white dolphins inhabit.
In 2011 World Wildlife Fund of Hong Kong identified more than 4,900 acres of dolphin habitat destroyed or altered in Hong Kong in the past 20 years from various completed and proposed developments
"The conservation effort in Hong Kong is not a lot," Hung said. The Hong Kong Dolphin Conservation Society has been conducting long-term monitoring research on the dolphins and amis to "gather more public support to fight against some of the development projects," that threaten the dolphins' survival.
WWF has also asked the Hong Kong government to adopt certain conservation measures to protect the Chinese white dolphins. The organization has called for the proposed Southwest Lantau Marine Park to change its designs to include more protected areas, and for fishing communities to assist in the management of protected areas.
Hong Kong officials announced last year that the 5,900-acre marine park would be protected from fishing, ferry traffic, and noise disruptions. However, the park won't be established until the airport expansion is finished, which could be as late as 2023.
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