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The Chinese White Dolphin (中華白海豚) (Sousa chinensis chinensis) is a subspecies of the Indo-Pacific Hump-backed Dolphin and is one of eighty cetacean species. The adult dolphin has a unique pink-coloured skin. The colour on the skin is not from colour pigments, but is actually from blood vessels for thermoregulation from overheating or exertion. The adult's body length is about 220 - 250 centimetres and the infant's body length is about 1 metre. The average weight of an adult is around 150 to 230 kilograms.
The Indo-Pacific dolphins can be found throughout Southeast Asia, and they breed from South Africa to Australia. There are two subspecies, with Sumatra, one of the Indonesia islands, as the dividing line between the Chinese and the Western subspecies, Sousa chinensis plumbea.
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2 Color changes in growth period 3 Life expectancy 4 Behaviour 5 Reproduction cycle 6 Population 7 Dolphin Watching 8 Threats 9 Timeline of main events 10 External links |
The two subspecies differ in color and size of their dorsal fin.
The subspecies found in Southeast Asia has pinkish white skin and a larger dorsal fin but lacks the fatty hump of its South African and Australian counterparts.
A Chinese White Dolphin can live as long as 40 years old. The eldest dolphin in Hong Kong was known to be 33 years old. Scientists can discover the age of a dead dolphin can be known by observing the cross section of its teeth.
Chinese White Dolphins swim to the water surface to breathe every 20 to 30 seconds and after that they will dive into deep water again. A calf surfaces from the water twice as much as an adult. This is because calves have a smaller lung capacity than an adult. Adult dolphins can stay underwater for about 2 to 8 minutes but a calf can only stay underwater for 1 to 3 minutes. On average, adult dolphins rarely stay under water for more than 4 minutes.
They sometimes jump out of water and expose their whole body. As they fall back into water, water droplets are splashed. This behavior, called breeching, is often impressive to human observers. Besides jumping out of water, White Dolphins also come up vertically out of the water, exposing the front half of the body. They have a pair of protruding eyes and they can see clearly in both air and water.
Chinese White Dolphins are quite sociable creatures and usually live in small groups of 3 to 4. Female white dolphins become mature at 10 years old while the males become mature at 13 years old. The Chinese White Dolphins usually mate from the end of summer to autumn. Infant dolphins are usually born 11 months after the mating. Mature female white dolphins can give birth every three years and the parental care will last until their offsprings can find food themselves.
There are about a thousand Chinese White Dolphins found in the Pearl River Delta, the body of water between Hong Kong and Macau. In Hong Kong waters, the total population of the dolphins is about 450-740, depending on the time of year. For example, in winter, there are about 130 dolphins in Hong Kong waters. The total population of the Chinese White Dolphins found in the whole area of the Pearl River Delta was about 1,050 in 1998. (Jefferson)
Hong Kong Dolphinwatch Ltd. has been running boat trips to visit the Chinese White Dolphins for the past five years. The dolphins mainly live in the waters of Lantau North, Southeast Lantau, the Soko Islands and Peng Chau. They primarily do this to raise awareness of Hong Kong citizens on the dolphins. Ten percent of the profits of the organization goes into research for Friends of the Earth (HK)'s Water Action Group, which is a charity aimed to raise public awareness of Hong Kong's coastal environment. The company runs trips every Wednesday, Saturday and Sunday. Further details can be obtained by contacting the Hong Kong Dolphinwatch Ltd. at " class="external">http://dolphins@pacific.net.hk.
The sea of Hong Kong is becoming a very dangerous habitat for the Chinese White Dolphins. This is due to the increasing numbers of poaching, landfills, and sea traffic. Since Chinese White Dolphins are territorial animals and rarely stray far away from their habitat, the water pollution in Hong Kong has a high impact on them.
Industrial, agricultural and domestic sewage are amongst the threats to the dolphins. In the Pearl River Delta, about 190,000 cubic metres of sewage is drained into the sea without any treatment daily. Tributyltin (TBT), an anti-fouling agent, affects the immune system of the dolphins. While organochlorines like PCBss and DDT may enter the food chain which may affect the dolphins as well as the whole ecosystem. Scientists are finding larger amounts of heavy metals, such as mercury, and organic materials in the corpses of Chinese White Dolphins.
As mentioned above, the construction of the Chek Lap Kok Airport resulted a 9.5 square kilometer loss of the prime dolphin habitat. Other construction projects like the North Lantau Expressway, river trade terminal between Tuen Mun and Castle Peak Power Station and the Disney's Theme Park, need further reclamation. This will further lead to a severe loss of the living habitats of the dolphins.
Overfishing and busy boat traffic near northern Lantau also threatens the lives of the dolphins. Overfishing may be a major danger to the dolphins because there are few regulations on the fishing industry set by the Hong Kong Government. There are many fish that are caught which become 'trash fish' because they are not the right size or species to be sold for profit. Therefore, dolphins have the risk of being caught and becoming 'trash fish' as well. As for boat traffic, there are about 70 boats that passes an average Hong Kong shipping channel daily. (Mak 1996) The noise made from boat engines causes danger of interfering with the dolphins' communication channels through echolocation.
Variation
Color changes in growth period
Life expectancy
Behaviour
Reproduction cycle
Population
Dolphin Watching
Threats
Timeline of main events
See also: Chinese River Dolphin