Eel reveals its migration secrets 欧洲鳗鲡迁徙产卵之谜
文章来源:未知 文章作者:meng 发布时间:2009-09-26 02:59 字体: [ ]  进入论坛
(单词翻译:双击或拖选)

The European eel1's migration2 to the Sargasso Sea to spawn3 is one of nature's great unsolved mysteries.

欧洲鳗鲡迁移到马尾藻海产卵是大自然未解开的最大的谜团之一。

Where do they all go?
Where do they all go?

For many years, biologists have puzzled over exactly where they go and what they do after leaving our rivers.

Now scientists using satellite tags have tracked 22 eels4, revealing what they do in the first 1,300km of an epic5(史诗的,叙事诗的) 5,000km migration.

Using this method, biologists hope the whole journey to the Sargasso Sea will soon be revealed.

The results of the tracking study are published in the journal Science.

They provide unique insights into the migratory6 behaviour of the European eel (Anguilla anguilla), including the direction and depth the eels(鳗鱼) swim.

"It's exciting data because no-one has managed to do this before," says Dr David Righton from the Centre for Environment, Fisheries and Aquaculture Science (CEFAS) in Lowestoft, UK, a member of the multinational7 team that undertook the study.

"People have often speculated about which direction eels may take, how they might travel, so what we've been able to show is which of those speculations8(沉思,推测) are actually right," Dr Righton says.

Ocean traveller

The European eel has a mysterious life cycle.

It spends its early years in our rivers before heading out to sea and across the Atlantic to the Sargasso Sea in the western Atlantic near the Bahamas.

Here, it is assumed they spawn and lay eggs, however this has never been witnessed.

The eggs hatch into transparent9 larvae10(幼虫,幼体) called leptocephalus(鳗的柳叶状幼体) and make the return journey to Europe floating on oceanic currents.

By the time they reach our shores, they have developed into tiny glass eels that swim against the current into Europe's rivers.

While living in our rivers, the eels can grow up to 1m long.

Conveyor belt

In 2006, the team attached miniaturised pop-up satellite tags to 22 large adult eels which they released from the coast of Galway, western Ireland.

The tags record not only the location of the eel but also the daily activity of the eel, recording11 speed, depth and direction.

The tags are set to "pop off" after six months and float to the ocean surface, sending data via satellite back to the research team.

"We found the direction the eels take wasn't a straight line from the west coast of Ireland towards the Sargasso Sea, but it was to the south of that, as if they were heading toward the Azores," Dr Righton explains.

"So basically they are heading towards the conveyor belt(传送带) ocean current which will help propel(推进,驱使) them toward the Sargasso Sea.

"That implies some navigational ability. It also suggests they are not just going the shortest distance; they are going the most efficient distance."

The researchers also found the eels swim too slowly to get to the Sargasso Sea by the April spawning12 period.

The researchers suggest this means the eels may gain speed and travel efficiency by entering the ocean currents that begin west of Africa and continue as part of the subtropical gyre(副热带环流) system that flows to the Caribbean.

Delaying puberty

The data also reveals that during the night eels swim in shallow warm water then at dawn they make a steep dive to a depth of 1,000m where they remain for the day before ascending13 again.

Eels do not feed on their migration and so this behaviour cannot relate to foraging14, though it may help them avoid predators15(掠夺者).

The researchers speculate that the shallow warm water helps the eels maintain a high metabolism16(新陈代谢), while the cooler water at depth delays the sexual development of the eels helping17 them maintain their streamline18 form.

"What we're publishing here is the first step towards finding out where the ultimate destination is," Dr Righton says.

"What we expect is with improvements in technology and improvements in our techniques and experience, we will see step changes in the data we are getting."

In 1922, the Danish scientist Johannes Schmidt first deduced(推论,演绎出) the Sargasso Sea as the spawning ground of the eel. Dr Righton hopes the final piece of the puzzle will soon be completed.

"Our project runs until 2012," he says, explaining that it would be fantastic to track the adults returning to the Sargasso Sea on the 90th anniversary of Schmidt's discovery.



点击收听单词发音收听单词发音  

1 eel bjAzz     
n.鳗鲡
参考例句:
  • He used an eel spear to catch an eel.他用一只捕鳗叉捕鳗鱼。
  • In Suzhou,there was a restaurant that specialized in eel noodles.苏州有一家饭馆,他们那里的招牌菜是鳗鱼面。
2 migration mDpxj     
n.迁移,移居,(鸟类等的)迁徙
参考例句:
  • Swallows begin their migration south in autumn.燕子在秋季开始向南方迁移。
  • He described the vernal migration of birds in detail.他详细地描述了鸟的春季移居。
3 spawn qFUzL     
n.卵,产物,后代,结果;vt.产卵,种菌丝于,产生,造成;vi.产卵,大量生产
参考例句:
  • The fish were madly pushing their way upstream to spawn.鱼群为产卵而疯狂地向上游挤进。
  • These fish will lay spawn in about one month from now.这些鱼大约一个月内会产卵。
4 eels 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。
5 epic ui5zz     
n.史诗,叙事诗;adj.史诗般的,壮丽的
参考例句:
  • I gave up my epic and wrote this little tale instead.我放弃了写叙事诗,而写了这个小故事。
  • They held a banquet of epic proportions.他们举行了盛大的宴会。
6 migratory jwQyB     
n.候鸟,迁移
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。
  • This does not negate the idea of migratory aptitude.这并没有否定迁移能力这一概念。
7 multinational FnrzdL     
adj.多国的,多种国籍的;n.多国籍公司,跨国公司
参考例句:
  • The firm was taken over by a multinational consulting firm.这家公司被一个跨国咨询公司收购。
  • He analyzed the relationship between multinational corporations and under-developed countries.他分析了跨国公司和不发达国家之间的关系。
8 speculations da17a00acfa088f5ac0adab7a30990eb     
n.投机买卖( speculation的名词复数 );思考;投机活动;推断
参考例句:
  • Your speculations were all quite close to the truth. 你的揣测都很接近于事实。 来自《现代英汉综合大词典》
  • This possibility gives rise to interesting speculations. 这种可能性引起了有趣的推测。 来自《用法词典》
9 transparent Smhwx     
adj.明显的,无疑的;透明的
参考例句:
  • The water is so transparent that we can see the fishes swimming.水清澈透明,可以看到鱼儿游来游去。
  • The window glass is transparent.窗玻璃是透明的。
10 larvae w2CxP     
n.幼虫
参考例句:
  • Larvae are parasitic on sheep.幼虫寄生在绵羊的身上。
  • The larvae prey upon small aphids.这种幼虫以小蚜虫为食。
11 recording UktzJj     
n.录音,记录
参考例句:
  • How long will the recording of the song take?录下这首歌得花多少时间?
  • I want to play you a recording of the rehearsal.我想给你放一下彩排的录像。
12 spawning e223115a66b2213a16c438abb9a400cb     
产卵
参考例句:
  • Encounter sites have a small chance of spawning a "Commander" NPC. 遭遇战地区有很小的几率遇到NPC指挥官。
  • Instantly revives your Champion at your Spawning Pool, 9 minute cooldown. 立即在出生地复活你的英雄,冷却时间9分钟。
13 ascending CyCzrc     
adj.上升的,向上的
参考例句:
  • Now draw or trace ten dinosaurs in ascending order of size.现在按照体型由小到大的顺序画出或是临摹出10只恐龙。
14 foraging 6101d89c0b474e01becb6651ecd4f87f     
v.搜寻(食物),尤指动物觅(食)( forage的现在分词 );(尤指用手)搜寻(东西)
参考例句:
  • They eke out a precarious existence foraging in rubbish dumps. 他们靠在垃圾场捡垃圾维持着朝不保夕的生活。 来自《简明英汉词典》
  • The campers went foraging for wood to make a fire. 露营者去搜寻柴木点火。 来自辞典例句
15 predators 48b965855934a5395e409c1112d94f63     
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》
16 metabolism 171zC     
n.新陈代谢
参考例句:
  • After years of dieting,Carol's metabolism was completely out of whack.经过数年的节食,卡罗尔的新陈代谢完全紊乱了。
  • All living matter undergoes a process of metabolism.生物都有新陈代谢。
17 helping 2rGzDc     
n.食物的一份&adj.帮助人的,辅助的
参考例句:
  • The poor children regularly pony up for a second helping of my hamburger. 那些可怜的孩子们总是要求我把我的汉堡包再给他们一份。
  • By doing this, they may at times be helping to restore competition. 这样一来, 他在某些时候,有助于竞争的加强。
18 streamline dtiwk     
vt.使成流线型;使简化;使现代化?
参考例句:
  • We must streamline our methods.我们必须简化方法。
  • Any liquid or gas passing it will have streamline flow.任何通过它的液体或气体将呈流线型的流动。
TAG标签: secret migration eel spawn
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