Decrease in Shark Population Harms Ocean 1)Ecosystems

Broadcast: Jan 16, 2003

 

Experts say one of the world's most feared, but misunderstood, creatures is under ²⁾assault by fishermen. A new study of all types of sharks finds that there are fewer of them than there used to be, and that is harming oceans' ecosystems¹.

A study in this week's journal Science is one of the first to look at the shark population. Researchers surveyed sharks in the northwest Atlantic, a vast area that encompasses² Newfoundland to the north and northern Brazil to the south, and stretches from the Gulf³ of Mexico to a distant point east off the coast of South of America.

Lead author Julia Baum says fisherman using long lines with up to a thousand hooks, designed to catch ³⁾swordfish and ⁴⁾tuna, are also snaring⁴ sharks. And Ms. Baum says this has resulted in huge shark declines.

"For hammerhead sharks, an 89 percent decline is what we are estimating for the past 15 years. That is a ⁵⁾phenomenal decline," she said. "Similarly, for the ⁶⁾thresher shark, we are estimating an decline 80 percent."

The study also found a 79 percent drop for white sharks and a 65 percent decline in tiger sharks since 1986.

Ms. Baum and colleagues at Dalhousie University in ⁷⁾Halifax, Canada used data from logbooks kept by fishermen, and they plugged it into a model to arrive at the estimates.

Ms. Baum says the use of hooked long lines is common all over the world, so it is safe to assume that shark populations are in steep decline globally. While many sharks are caught by accident in long lines, she says shark fins⁵ are prized throughout Asia to make soup, so there is a ⁸⁾deliberate effort to catch them as well.

Many people might ask why it is important to worry about fewer sharks, because they are predators⁶ and will attack humans.

"The number of attacks throughout the world is fairly minimal," Malcolm Smale is marine⁷ biologist with the Port Elizabeth Museum in South Africa.

"For example, in South Africa, we only have about three to five attacks per year on average. Less than one per year is fatal. And this is a much lower number than any other cause of injury or fatality⁸, for example, road accidents, people getting shot in burglaries, people drowning, people struck by lightning and so on," he added.

But sharks are the oceans' top ⁹⁾predator. As such, Mr. Smale says they eat smaller, weaker fish and those that may be unfit for human consumption.

"Now, one might think that is not such a bad thing. But in reality, what we would call pest species - those with very rapid cycles, in other words, they breed within a year or two - are likely to become more common," he said. "And on the one hand, that might be thought to be a good thing if they are edible⁹, but in many cases these species might be pest species, in other words, not suitable for human consumption. And so this is ¹⁰⁾detrimental for both humans and the food web."

Experts say unlike the fish they eat, sharks have long life cycles, and it could take years to ¹¹⁾replenish their numbers, if that is possible. In the meantime, Canadian researchers suggest preserving the shark population by discouraging over-fishing and establishing marine reserves.

Jessica Berman VOA news, Washington.

1)      ecosystems[i:kE5sistEm]n. 生态系统

2)      assault[E5sC:lt]n. 攻击, 袭击

3)      swordfish[5sC:dfIF]n. [鱼] 旗鱼

4)      tuna[5tju:nE]n. 金枪鱼

5)      phenomenal[fi5nCminl]adj. 显著的, 现象的, 能知觉的

6)      thresher[5WreFE(r)]n. [鱼]长尾鲨

7)      halifax[5hAlifAks]哈利法克斯(①加拿大省会 ②英国城市)

8)      deliberate[di5libEreit]adj. 深思熟虑的

9)      predator[5predEtE]n. 掠夺者,食肉动物

10)  detrimental[7detri5mentl]adj. 有害的

11)  replenish[ri5pleniF]v. 补充

1 ecosystems   

n.生态系统( ecosystem的名词复数 )

参考例句：

• There are highly sensitive and delicately balanced ecosystems in the forest. 森林里有高度敏感、灵敏平衡的各种生态系统。 来自《简明英汉词典》
• Madagascar's ecosystems range from rainforest to semi-desert. 马达加斯加生态系统类型多样，从雨林到半荒漠等不一而足。 来自辞典例句

2 encompasses   

v.围绕( encompass的第三人称单数 )；包围；包含；包括

参考例句：

• The job encompasses a wide range of responsibilities. 这项工作涉及的职责范围很广。
• Its conservation law encompasses both its magnitude and its direction. 它的守恒定律包括大小和方向两方面。 来自辞典例句

3 gulf   

n.海湾；深渊，鸿沟；分歧，隔阂

参考例句：

• The gulf between the two leaders cannot be bridged.两位领导人之间的鸿沟难以跨越。
• There is a gulf between the two cities.这两座城市间有个海湾。

4 snaring   

v.用罗网捕捉，诱陷，陷害( snare的现在分词 )

参考例句：

• They have the ability to perform mucosal biopsies, cautery and even snaring polyps. 他们能够学习肠粘膜活检、烧灼、甚至肠息肉套扎术。 来自互联网

5 fins   

[医]散热片；鱼鳍；飞边；鸭掌

参考例句：

• The level of TNF-α positively correlated with BMI,FPG,HbA1C,TG,FINS and IRI,but not with SBP and DBP. TNF-α水平与BMI、FPG、HbA1C、TG、FINS和IRI呈显著正相关，与SBP、DBP无相关。 来自互联网
• Fins are a feature specific to fish. 鱼鳍是鱼类特有的特征。 来自辞典例句

6 predators   

n.食肉动物( predator的名词复数 )；奴役他人者（尤指在财务或性关系方面）

参考例句：

• birds and their earthbound predators 鸟和地面上捕食它们的动物
• The eyes of predators are highly sensitive to the slightest movement. 捕食性动物的眼睛能感觉到最细小的动静。 来自《简明英汉词典》

7 marine   

adj.海的；海生的；航海的；海事的；n.水兵

参考例句：

• Marine creatures are those which live in the sea. 海洋生物是生存在海里的生物。
• When the war broke out,he volunteered for the Marine Corps.战争爆发时，他自愿参加了海军陆战队。

8 fatality   

n.不幸，灾祸，天命

参考例句：

• She struggle against fatality in vain.她徒然奋斗反抗宿命。
• He began to have a growing sense of fatality.他开始有一种越来越强烈的宿命感。

9 edible   

n.食品，食物；adj.可食用的

参考例句：

• Edible wild herbs kept us from dying of starvation.我们靠着野菜才没被饿死。
• This kind of mushroom is edible,but that kind is not.这种蘑菇吃得，那种吃不得。