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« ตอบ #1 เมื่อ: เมษายน 11, 2007, 01:42:44 AM » |
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Marine biologist Kanjana Adulyanukosol, Thailand's leading authority on dugongs.
Despite sightings of several cows with young calves, Kanjana's aerial surveys of Thai waters recorded an overall dugong population of only 250. "In the Andaman Sea, from Ranong, Phangnga, Phuket and Krabi to Trang and Satun there were around 200, and in the Gulf of Thailand from Chon Buri, Rayong, Chanthaburi and Trat down to Chumphon and Surat Thani we counted a total of 50," she said.
The death rate of dugongs is high because they feed on grass in shallow waters, where they are caught in fishermen's nets or fish traps. "Dugongs can die of shock," Kanjana said. "When they panic they stop breathing. While feeding they have to come up for air every few minutes, so when they are caught in a net or fish trap they can't come up for air and die."
In the past, the belief that eating dugong meat could give a person a long life led to them being hunted to near extinction. Bones were powdered and used as medicine for a number of ailments, tusks were fashioned into amulets or stones for rings, and skins were dried and made into walking sticks or slippers. Some villagers even believed that dugong tears could be used as an aphrodisiac, or as a potion that a man could use to win the heart of the woman he loved.
These beliefs are no longer prevalent, yet the dugong population remains small. This is because of their low birth rate, Kanjana said.
"Like humans they can live to the ripe old age of 70, but they are not ready to mate until they are over 10. Gestation takes one year, and the mother can only give birth to one calf at a time, and then she will nurse her calf for two years. It takes three to seven years before she is ready to mate again."
Kanjana observed that dugongs prefer to mate in shallow water, with the male touching the female's chest, belly and genitals with its muzzle during courtship. They then swim side by side before he mounts her, followed by a lot of water splashing. Afterwards, they swim in different directions, with neither seeming to be interested in the other.
A newly born dugong is very slim, about 1.2m long, and weighs between 20 and 35kg, Kanjana said. It soon grows to 3m long with an average weight of 300kg. Only 20 to 30 per cent of the body weight comprises meat; the rest is fat.
Dugongs eat at least 30kg of grass, or an average of 10 per cent of their body weight, every day, Kanjana said. There's no shortage of the dugong's favourite sea grass, Halophila ovalis, in Thai waters, she added.
When not making her aerial surveys or observing dugongs in their natural habitat, Kanjana writes cartoon books for children. Needless to say, her books focus on dugongs, to increase public awareness of what she sees as the most pitiful creatures of the sea.
Although a native of the coastal province of Samut Sakhon, Kanjana was born in a village by a khlong in Damnern Saduak. It was not until after she had joined the Phuket Marine Biological Centre (PMBC) 20 years ago that she saw her first dugong.
"A trawler in Satun caught a young dugong and its mother in its nets," she recalled. "The mother died, but the fishermen brought the calf to shore."
The calf, a male less than a year old, was brought to the PMBC and Kanjana was given the task of caring for him. She swam with the calf and acted as its surrogate mother. Unfortunately it died a month later, but by then Kanjana was hooked on dugongs.
In 1993, when the Marine Endangered Species Unit was set up, she asked to be moved to the unit so she could carry out research on dugongs, and she has since established a name for herself as Thailand's leading authority on them. A report co-authored by Kanjana on their mating behaviour, the first such report on dugongs in tropical Asian regions, has just been published by the scientific journal Marine Biology.
Dugongs can be found in tropical waters from East Africa to Papua New Guinea, and up to Okinawa and China, but their numbers are small, Kanjana said. The only country that has a large dugong population is Australia, which protects this marine species well.
"Australians look after their marine parks well, and they have zoning that prohibits speedboats from entering certain areas and limits their speed in certain areas. Aborigines are allowed to catch dugongs because hunting and eating them is part of their culture. Still, Australia has a dugong population of over 100,000, because the Aborigines are allowed to hunt only a certain number per year and the laws are strictly enforced."
Thailand has laws protecting the dugong as an endangered species, but these are not enforced, Kanjana said. "Dugongs are still being caught in fishing nets, because fishermen continue to fish in restricted areas.
"My dream as an academic is to have action plans and laws that are enforced by the authorities and observed by the people," she mused. "I don't want to have action plans only on paper which are admired by scientists when presented at meetings abroad, but are useless because of lack of implementation.
"People often ask, 'Can dugongs be cloned? Or bred by artificial insemination?' Even Japan, which is very advanced technologically, has not been able to breed dugongs it has been raising in an aquarium for 20 years. Taken from the Philippines, the dugongs, a male and a female, won't mate, probably because the food is not as plentiful or as rich as in the wild, and the conditions where they are kept are not the same.
"In short, taking dugongs from the wild and raising them in captivity with the purpose of breeding them cannot be done. The best way to sustain the dugong population is by protecting their natural habitat, especially in places where the population is high, as in Trang.
"If the dugong habitat is well protected, the animals will breed naturally, and their number will increase."
Yet, although Kanjana knows dugongs by heart - having observed their eating, mating, child-rearing and social behaviour - there's one thing that still baffles her: Where do the dugongs go when the tide is out?
The only way to know is to tag them. "This would be a very exciting and challenging project, but dugongs just stop breathing when they panic, so how can we catch and tag them without killing them?
"All along I've worked and campaigned for the protection of dugongs, and if tagging them would cause injury or even death, how could I look people in the eye?" ********************************************************************** เป็นบทความเกี่ยวกับการทำงานของ "แม่หมูน้ำ"โดย Normita Thongtham ลงตีพิมพ์ใน Bangkok Post ฉบับวันที่ 1 เมษายน 2550
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