密歇根新闻广播 如何控制七鳃鳗数量

A number of destructive invasive species have invaded the Great Lakes in the past several decades. These non-native creatures can do significant damage to native ecosystems¹. Biologists work hard to control them, but it's an ongoing³ battle.

Cory Brant of the Great Lakes Fishery Commission has captured the story of one particularly prolific⁴ invasive species in his new book Great Lakes Sea Lamprey: The 70 Year War on a Biological Invader⁵.

Brant referred to sea lampreys as the little vampires⁶ of the Great Lakes. As that nickname suggests, the parasitic⁷ creatures can be devastating⁸ to local fish populations.

[Sea lampreys] swim up alongside a fish and attach themselves to the side… [They] end up wearing away scales, breaking away capillaries⁹, and getting a pretty good blood meal, Brant said.

The large, parasitic fish are originally from the Atlantic Ocean. Most experts think that they first got to the Great Lakes through the Welland Canal, which was built to allow ships travelling from Lake Ontario to Lake Erie to bypass Niagara Falls. Once they made it into Lake Erie, Brant said, sea lampreys had free range of the Great Lakes Basin.

People initially¹⁰ weren't too worried about the sea lamprey, Brant explained. From the 1920s through the 1940s, industrial dumping, pollution, and habitat loss in the Great Lakes meant that the fish didn't have much to feed on.

By 1949, though, lake trout¹¹ and whitefish populations — which Brant called the bread and butter of the Great Lakes fishery — began to plummet¹². The fish that did survive sea lamprey attacks looked mangled¹³ and diseased.

Biologists tried a range of methods to control the fish. They used basket traps, electric fences, and even brought in American eels¹⁴ to feed on larval sea lamprey. But none of those efforts proved effective. By the mid-1950s, Brant said that an estimated 100 million pounds of fish were killed by sea lampreys every year.

That's when those researchers turned to a new method: poison. Specifically, a selective toxicant that would only kill sea lampreys, and not the native fish they preyed¹⁵ on.

It was called the ‘era of the pickle¹⁶ jar biologist,' where they would essentially¹⁷ get tons of pickle jars, put a few lamprey in — larval lamprey, little babies, Brant explained. Then they'd put a few bluegills in or some other small fish [like] a few rainbow trout, and then they would add all these chemicals and see what died first.

Nowadays, it costs about $20 million annually¹⁸ for the Great Lakes Fishery Commission to keep the sea lamprey population under control. They haven't been totally eliminated, but the population is around 10% what it once was. Brant argues that's a small price to pay considering what would happen if those control efforts were relaxed.

He said that sea lampreys would make a quick comeback, and feed on any large-bodied fish they could find, including lake trout, Chinook salmon¹⁹, and the endangered sturgeon.

Sea lampreys — just like zebra mussels — are major ecosystem² disruptors, Brant said. If we let up, they make a comeback.

This post was written by Stateside production assistant Isabella Isaacs-Thomas.

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 ecosystem   

n.生态系统

参考例句：

• This destroyed the ecosystem of the island.这样破坏了岛上的生态系统。
• We all have an interest in maintaining the integrity of the ecosystem.维持生态系统的完整是我们共同的利益。

3 ongoing   

adj.进行中的，前进的

参考例句：

• The problem is ongoing.这个问题尚未解决。
• The issues raised in the report relate directly to Age Concern's ongoing work in this area.报告中提出的问题与“关心老人”组织在这方面正在做的工作有直接的关系。

4 prolific   

adj.丰富的，大量的；多产的，富有创造力的

参考例句：

• She is a prolific writer of novels and short stories.她是一位多产的作家，写了很多小说和短篇故事。
• The last few pages of the document are prolific of mistakes.这个文件的最后几页错误很多。

5 invader   

n.侵略者，侵犯者，入侵者

参考例句：

• They suffered a lot under the invader's heel.在侵略者的铁蹄下，他们受尽了奴役。
• A country must have the will to repel any invader.一个国家得有决心击退任何入侵者。

6 vampires   

n.吸血鬼( vampire的名词复数 )；吸血蝠；高利贷者；（舞台上的）活板门

参考例句：

• The most effective weapon against the vampires is avampire itself. 对付吸血鬼最有效的武器就是吸血鬼自己。 来自电影对白
• If vampires existed, don`t you think we would`ve found them by now? 如果真有吸血鬼，那我们怎么还没有找到他们呢？ 来自电影对白

7 parasitic   

adj.寄生的

参考例句：

• Will global warming mean the spread of tropical parasitic diseases?全球变暖是否意味着热带寄生虫病会蔓延呢？
• By definition,this way of life is parasitic.从其含义来说，这是种寄生虫的生活方式。

8 devastating   

adj.毁灭性的，令人震惊的，强有力的

参考例句：

• It is the most devastating storm in 20 years.这是20年来破坏性最大的风暴。
• Affairs do have a devastating effect on marriages.婚外情确实会对婚姻造成毁灭性的影响。

9 capillaries   

毛细管，毛细血管( capillary的名词复数 )

参考例句：

• The blood flows from the capillaries back into the veins. 血从毛细血管流回静脉。
• While Joe sleeps, a large percentage of his capillaries are inactive. 当乔睡觉时，他的毛细血管大部分是不工作的。

10 initially   

adv.最初，开始

参考例句：

• The ban was initially opposed by the US.这一禁令首先遭到美国的反对。
• Feathers initially developed from insect scales.羽毛最初由昆虫的翅瓣演化而来。

11 trout   

n.鳟鱼；鲑鱼(属)

参考例句：

• Thousands of young salmon and trout have been killed by the pollution.成千上万的鲑鱼和鳟鱼的鱼苗因污染而死亡。
• We hooked a trout and had it for breakfast.我们钓了一条鳟鱼，早饭时吃了。

12 plummet   

vi.(价格、水平等)骤然下跌；n.铅坠；重压物

参考例句：

• Mengniu and Yili have seen their shares plummet since the incident broke.自事件发生以来，蒙牛和伊利的股票大幅下跌。
• Even if rice prices were to plummet,other brakes on poverty alleviation remain.就算大米价格下跌，其它阻止导致贫困的因素仍然存在。

13 mangled   

vt.乱砍（mangle的过去式与过去分词形式）

参考例句：

• His hand was mangled in the machine. 他的手卷到机器里轧烂了。
• He was off work because he'd mangled his hand in a machine. 他没上班，因为他的手给机器严重压伤了。 来自《简明英汉词典》

14 eels   

abbr. 电子发射器定位系统（=electronic emitter location system）

参考例句：

• Eels have been on the feed in the Lower Thames. 鳗鱼在泰晤士河下游寻食。
• She bought some eels for dinner. 她买回一些鳗鱼做晚餐。

15 preyed   

v.掠食( prey的过去式和过去分词 )；掠食；折磨；（人）靠欺诈为生

参考例句：

• Remorse preyed upon his mind. 悔恨使他内心痛苦。 来自《现代英汉综合大词典》
• He had been unwise and it preyed on his conscience. 他做得不太明智，这一直让他良心不安。 来自辞典例句

16 pickle   

n.腌汁，泡菜；v.腌，泡

参考例句：

• Mother used to pickle onions.妈妈过去常腌制洋葱。
• Meat can be preserved in pickle.肉可以保存在卤水里。

17 essentially   

adv.本质上，实质上，基本上

参考例句：

• Really great men are essentially modest.真正的伟人大都很谦虚。
• She is an essentially selfish person.她本质上是个自私自利的人。

18 annually   

adv.一年一次，每年

参考例句：

• Many migratory birds visit this lake annually.许多候鸟每年到这个湖上作短期逗留。
• They celebrate their wedding anniversary annually.他们每年庆祝一番结婚纪念日。

19 salmon   

n.鲑，大马哈鱼，橙红色的

参考例句：

• We saw a salmon jumping in the waterfall there.我们看见一条大马哈鱼在那边瀑布中跳跃。
• Do you have any fresh salmon in at the moment?现在有新鲜大马哈鱼卖吗？