Yangtze dolphin on verge of extinction_科学技术

Yangtze dolphin on verge of extinction

文章来源：文章作者：发布时间：2006-12-04 01:08 字体： [大中小]　进入论坛

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A white-flag dolphin.

Dec.3 - A team of 30 Chinese and foreign scientists have failed in a 26-day search to find the rare white-flag dolphin in the Yangtze River.

The white-flag dolphin is more endangered than the giant panda due to the pollution and environmental degradation¹, said Wang Ding, vice² director of the hydrobiology institute of the Chinese Academy of Sciences.

The last expedition in 1997 located 13 white-flag dolphins, the world's rarest dolphin, which lives only in China's longest river, the Yangtze.

"We can't say the white-flag dolphin is extinct," said Wang. "However, the population has dropped dramatically over the past decade."

Wang and his colleagues estimate that no more than 50 are left.

If the white-flag dolphin disappears on earth, it will be the first whale species extinct due to human activities. More than 90 percent of deaths of the white-flag dolphins were caused by human activities, scientific data showed.

During the 1,700-kilometer expedition from Yichang to Shanghai, the scientists found the population of black finless³ porpoises⁵ had also fallen.

In addition to deck observers equipped with high-performance telescope to spot dolphins, the team members used hydrophone machines to detect acoustic⁶ signals from the dolphins.

They have obtained some sound records during the expedition which needs more analysis. It's the last hope of the scientists, Wang said.

A patrolman of the fishery administration was reported to see the rare dolphin for the last time in April this year. But he didn't take a photo of the dolphin, and scientists were not sure it was a real white-flag dolphin. Since then there were no such reports.

Wang said pollution, overfishing, shipping⁷ and a large number of water conservancy projects had affected⁸ the habitats of the animals.

Illegal fishing by means of electric shock, poisons and explosives will accidentally injure and kill the dolphins, said scientists.

The white-flag dolphins have bad eyesight and use their own sonar system for orientation⁹. The noises of ships will disturb the sonar system of the dolphins which are easy to get killed in the screws of the ships.

The dolphins also require a clean water living environment. Scientists have got water samples of the Yangtze River, which will be sent to a lab in Switzerland to analysis the pollutants¹⁰.

"If the situation cannot be improved, the white-flag dolphin may be extinct within ten years, and the black finless porpoise⁴ will also be endangered," Wang said.

There are an estimated 1,000 black finless porpoises in the river, dropping by half from 12 years ago, according to Wang.

After a short rest in Shanghai, the scientists will return to Huhan from Shanghai and will continue their search for the rare species in the Yangtze River.

If any white-flag dolphin is discovered, it will be taken to natural reserve for protection, according to the scientists.

A conservation base for white-flag dolphin has been set up in a lake in central China's Hubei Province. However, no white-flag dolphin pairs have been caught in the lake in the past ten years, increasing the difficulty of artificial propagation.

Some scientist say the only way to save the species is to improve the environment of the Yangtze River.

Conservation work on the Yangtze freshwater dolphins started from 1986. The Chinese government has established six natural reserves to protect them along the middle and lower reaches of the Yangtze River.

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收听单词发音

1 degradation
n.降级；低落；退化；陵削；降解；衰变
参考例句：
There are serious problems of land degradation in some arid zones.在一些干旱地带存在严重的土地退化问题。 Gambling is always coupled with degradation.赌博总是与堕落相联系。

2 vice
n.坏事；恶习；[pl.]台钳，老虎钳；adj.副的
参考例句：
He guarded himself against vice.他避免染上坏习惯。 They are sunk in the depth of vice.他们堕入了罪恶的深渊。

3 finless
adj.无鳍的
参考例句：
The Finless Porpoise is another resident marine mammal species. 此外，江豚是另一种在本港海域栖居的海洋哺乳类动物。来自互联网 The finless eel ate the earthworm in front in one bite. 黄鳝一口就把眼前的蛐蟮吃掉了。来自互联网

4 porpoise
n.鼠海豚
参考例句：
What is the difference between a dolphin and porpoise?海豚和和鼠海豚有什么区别？ Mexico strives to save endangered porpoise.墨西哥努力拯救濒危的鼠海豚。

5 porpoises
n.鼠海豚( porpoise的名词复数 )
参考例句：
A shoal of porpoises are well on the feed. 一群海豚正在吞食。来自辞典例句 In 1928 some porpoises were photographed working like beavers to push ashore a waterlogged mattress. 1928年有人把这些海豚象海狸那样把一床浸泡了水的褥垫推上岸时的情景拍摄了下来。来自辞典例句

6 acoustic
adj.听觉的，声音的；(乐器)原声的
参考例句：
The hall has a fine acoustic.这个大厅的传音效果很好。 Animals use a whole rang of acoustic, visual,and chemical signals in their systems of communication.动物利用各种各样的听觉、视觉和化学信号来进行交流。

7 shipping
n.船运（发货，运输，乘船）
参考例句：
We struck a bargain with an American shipping firm.我们和一家美国船运公司谈成了一笔生意。 There's a shipping charge of ￡5 added to the price.价格之外另加五英镑运输费。

8 affected
adj.不自然的，假装的
参考例句：
She showed an affected interest in our subject.她假装对我们的课题感到兴趣。 His manners are affected.他的态度不自然。

9 orientation
n.方向，目标；熟悉，适应，情况介绍
参考例句：
Children need some orientation when they go to school.小孩子上学时需要适应。 The traveller found his orientation with the aid of a good map.旅行者借助一幅好地图得知自己的方向。

10 pollutants
污染物质（尤指工业废物）( pollutant的名词复数 )
参考例句：
Pollutants are constantly being released into the atmosphere. 污染物质正在不断地被排放到大气中去。 The 1987 Amendments limit 301(g) discharges to a few well-studied nonconventional pollutants. 1987年的修正案把第301条（g）的普通排放限制施加在一些认真研究过的几种非常规污染物上。来自英汉非文学 - 环境法 - 环境法

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