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No mercy White dolphin tours may disturb habitat By Sally Tse |
Courtesy of Mr. John M.K. Wong |
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According to Mr. John M. K. Wong, vice chairperson of Hong Kong Marine Conservation Society, the noise from motorized engines interferes with the dolphins’ lives in two ways. Firstly, Chinese white dolphins look for food by “echo-location” and use sounds to make their way round the murky black water. Man-made noise lowers their hunting ability. Secondly, the noise also disturbs dolphins’ daily routines as they communicate with one another by sound. This is especially a problem for mothers with calves. “Most watchers neither know much about the dolphins’ behaviour, nor do they care about them,” said Mr. Wong. “They sometimes feed the creatures with unsuitable food, such as snacks. “And some chase the dolphins for fun, scaring and hurting them,” he added. He suggested a licensing policy which would ensure only knowledgeable boat owners could get near the dolphins’ habitats. The general manager of Jubilee International Tour Centre, Mr. Johnny K. K. Lee, admitted that some tours cause annoyance to dolphins, but added that his firm takes precautions not to disrupt their environment. “The sounds of engines and watchers’ voices are hard to avoid, and there is no code of conduct for the participants to follow,” he said. However, he said that his firm’s normal operating practices do not compromise the white dolphins’ living routines. The speed of cruisers is limited to 8 knots so as to get close to the dolphins and have better observations. “There is no littering or oil leakage because these are offences under law,” said Mr. Lee. He said that the real problem is not tourism, but the construction of the new airport in Chak Lap Kok. The Brother Lands, an ideal living and mating area for Chinese white dolphins, was levelled to facilitate the dredging and construction work for the new airport. “White dolphins were forced to leave their home, where they had been living for generations,” said Mr. Bill Leverett, the founder and now the general manager of Hong Kong Dolphin Watch. Besides the physical loss of 9 square kilometres of sea area due to the reclamation for the new airport, the construction of expressways near Lantau Island modified the natural coastline, leaving less and less room for the dolphins. Said Mr. Leverett: “The white dolphins are now packed in a much smaller living place, with greater competition for food.” Mr. Wong explained, “The dolphins prefer to live in river delta areas. “They like quiet, clean and shallow water less than 20 metres deep. “They are found near islands that are sheltered from the high sea waves and strong winds, such as Chak Lap Kok, Lung Kwu Chau, the Brother Lands, Tai O and Sha Chau.” Said Mr. Leverett: “Marine traffic, pollution and over-fishing disturb the white dolphins. According to the World Wide Fund for Nature Hong Kong, the great noise produced by explosions at construction sites around Lantau Island affects the dolphins’ sensitivity to sound waves. In extreme cases, the explosions may cause injuries in their lungs. High-speed boats carrying construction materials and workers to and from Chak Lap Kok collide with the white dolphins at times, causing death. Another natural habitat for the Chinese white dolphins, East Sha Chau, has been chosen by the government as a dumping site. Up to 30 million cubic metres of contaminated mud by-products will be dumped there by 2000. The mud contains toxic substances, like heavy metals. High levels of poisoning have already been observed in the tissues of dead calves and male dolphins. Viruses and bacteria contained in untreated or under-treated sewage flowing directly into the sea can also be fatal. The population is clearly under threat. Because of dwindling food supplies due to over-fishing and water pollution, Chinese white dolphins sometimes chase fishing boats for food. They sometimes are injured by steel fishing nets or even cut by the operating propellers. The death rate of the Chinese white dolphins has risen alarmingly within the past 10 years. Before 1993, the average number of Chinese white dolphin carcasses recorded every year was two, according to Mr. Wong. Between 1994 to 1996, the number jumped to 10. But this is the reported figure only, and other fatalities may have gone unreported. “We can imagine that there are many more deaths not being discovered among the 80 to 140 white dolphins living in Hong Kong waters,” said Mr. Leverett. While some commercial dolphin watching tours are said to be harmful to the dolphins’ living environment, Hong Kong Dolphin Watch organises non-profit making tours aimed at arousing people’s awareness on the protecting the dolphins. Said Mr. Leverett: “We watch the dolphins with a respectful attitude. “There are certain instructions for the watchers to follow. “For example, they are prohibited from swimming with the white dolphins. Feeding, shouting and throwing objects to the animals are not allowed.” To Miss Lister Cheung, general secretary of the Conservancy Association, dolphin watching should not be regarded as merely an entertainment. “People can understand the lives of the dolphins through video shows and slide shows, which many environmentalists are generous to provide,” said Miss Cheung. She also revealed the importance of mass media in informing the public about the urgency of reviving the endangered dolphins. In November 1996, Sha Chau Marine Park for Dolphins was established to provide a sheltered and safe habitat for them. The sanctuary prohibits vessels of certain categories, such as fishing boats. The noise level and the speed of ships sailing near the area are also subject to limitations. “But the protection measures came a bit late. It is impossible to replace a natural environment with artificially altered ones,” said Miss Cheung. |
Boffins baffled
November 1997
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