Eli the eel: A mysterious migration - James Prosek

鳗鱼伊莱:神秘的迁徙 - 詹姆斯·普罗斯科

Transcriber: Jessica Ruby Reviewer: Caroline Cristal

翻译人员: Xiaoou Chen 校对人员: Liang Chen

They're long and slithery,

他们（体态）修长并且（皮肤）黏滑，

and they're not very colorful.

但不是非常色彩斑斓。

But they do have a strange beauty of their own.

但是它们有其独特的魅力。

Their sinuous, nocturnal movements

它们夜间蜿蜒

through the water

are mesmerizing to watch.

从水中游过

看起来让人着迷。

And though they may resemble underwater snakes,

即使他们像水下的蛇，

eels are, in fact, a very interesting type of fish.

但事实上鳗鱼是一种非常有趣的鱼。

There are several things about eels

除了它们修长无四肢的身体

that make them unique

有几个特征

besides their elongated shape and limbless bodies.

让鳗鱼独具一格。

For one thing,

第一个，

eels have the ability to breathe through their skin.

鳗鱼可以透过它们的皮肤来呼吸。

Some can even leave the water

有些鳗鱼甚至可以离开水

and move over land for short periods.

在陆地上存活一小段時間。

And, unlike most migratory fish,

不像大多数迁徙性鱼类，

such as salmon,

比如三文鱼，

which spawn in fresh water

它们在淡水中产卵

but live their adult lives in salt water,

但是成年鳗鱼生活在盐水中，

eels of the genus Anguilla

安圭拉属的鳗鱼

migrate in the opposite direction,

以相反的方向迁徙，

spawning and breeding in oceans and seas,

它们在海洋中产卵和繁殖

while spending most of their intervening time

而大部分的时间

in fresh water.

生活在淡水中。

If we were to take one such fresh water eel

如果我们那这样一条淡水鳗鱼

and follow its life story,

并跟随它的生活故事，

it would be born in the middle of the North Atlantic Ocean,

它将会出生于北大西洋中间，

about a thousand miles east of Bermuda.

位于百慕达东侧约一千英里。

This area, called the Sargasso Sea,

这块叫马尾藻海的地域

forms the western part

形成了副热带环流

of a subtropical gyre,

西部的一个部分。

a giant whirlpool in the middle of the ocean.

副热带环流是海洋中一个巨大的漩涡。

Our eel, let's call it Eli,

让我们叫我们的鳗鱼伊莱

would begin as one of ten to twenty million tiny eggs,

它的生命从那两千万分之一的一枚

carried by a female eel,

被雌性鳗鱼携带的卵开始，

hatching into a transparent leaf-shaped thing

雌性鳗鱼将它们孵化成为透明叶状的东西，

that looks nothing like an adult eel.

看起来一点也不像成年鳗鱼。

Eli starts to drift in ocean currents,

伊莱开始随着海浪漂流，

predominantly the Gulf Stream

主要位于通向欧洲或被没的

towards either Europe or North America,

墨西哥湾暖流，

depending on its particular species.

其去向取决于其物种。

Upon reaching the coast,

快要到岸边时，

Eli is about two inches long,

伊莱大概有两英尺长（约5厘米），

looking more eely but still transparent,

看上去更像鳗鱼了，但还是透明的，

known at this stage as a glass eel.

这个阶段叫做鳗鱼鱼苗。

But within a couple of days in fresh water,

但是在几天的淡水生活中，

Eli's skin becomes pigmented a brownish-black,

伊莱的皮肤被色素变成了棕黑色，

now looking more like that of an adult eel.

现在就看上去就更像成年鳗鱼了。

You might notice

你可能会注意到

that we haven't mentioned anything

我们还没有提及

about Eli's gender yet.

关于伊莱的性别。

That's because this is only determined

那是因为性别是在它

once an eel enters fresh water,

进入到淡水区所决定的，

though nobody is sure exactly how that happens.

没有人知道那是怎么发生的。

Most of the eels that stay in the estuaries

大部分生活在河口

and brackish water become males,

和盐水区的鳗鱼成为了雄性，

while those that go upstream become females,

上流的鳗鱼成为了雌性，

growing up to two to three times bigger than

会找到比她们未来的配偶

their future mates.

大两到三倍。

In this case,

在这种情况下，

it turns out that Eli was actually short for Elaine.

我们就知道伊莱是伊莱恩的简称。

As a female eel,

作为一条雌性鳗鱼，

Elaine will be quite solitary

伊莱恩在细流中的大部分的生活

for most of her life in the stream,

都是非常孤独的，

eating whatever falls in the water:

吃仍何掉入水中的东西：

grasshoppers, crickets, small fish,

蚱蜢，蟋蟀，小鱼，

insect larvae, frogs, baby birds,

昆虫幼虫，青蛙，幼鸟，

almost anything she can get her mouth around.

几乎任何到她嘴边的东西。

And she will grow quite big,

她可以长得非常大

up to four feet long

直到有四英寸长（约1.2米）

and weighing as much as thirteen pounds.

重三十磅。

We don't know exactly how

我们不明确知道

fresh water eels know when it's time

淡水鳗鱼是如何知道何时

to return to the ocean,

返回海洋的，

but something calls to them.

但有东西在召唤它们。

And their fall migration

它们秋季的迁徙

is one of the largest unseen migrations

是这个星球上规模最大的

on the planet.

不可见的迁徙之一。

As Elaine leaves fresh water for the ocean,

当伊莱恩离开淡水前往海洋时

she undergoes a shocking metamorphosis.

她会经历令人震惊的变异。

Her eyes enlarge by about ten times,

她的眼睛增大十倍，

her skin gets thicker,

皮肤变厚，

and her fins get larger.

她的鳍也变大。

These are most likely adaptations

这些非常有可能是他们

for their upcoming ocean travel,

为了未来海洋旅行的适应，

and Elaine seamlessly makes the transition

伊莱恩在从淡水到海洋的过程中

from fresh to salt water,

完美地完成了这个转变，

which would be toxic for most other fish.

而这盐水对别的鱼是有害的。

Once Elaine leaves the mouth of the fresh water streams,

一旦伊莱恩离开了淡水溪流的河口

she will disappear completely from human view.

她将会永远的从人类的视野中消失。

No one has witnessed,

没有人可以目睹

or been able to follow,

或追踪

an adult eel on their migration,

成年鳗鱼的迁徙，

nor do we know how deep they spawn.

我们也不知道他们在多深的地方产卵。

But it's assumed that they can follow some signs

他们被认为可以顺着

that they can detect,

他们可以探测到的标识（找到路线）

such as a thermal barrier between ocean currents

比如洋流间的热障

or a salinity front,

或是盐度，

in order to return to the same area of the ocean

以这样的方式返回到海洋中

where they were born.

他们出生的地方。

Because we don't even know exactly

因为我们压根就不知道

what happens during an eel's migration,

在鳗鱼的迁徙中发生了什么，

we can only imagine what the actual breeding looks like.

我们只能去想象他们繁殖的方式。

But the common hypothesis

但是一个普遍的假说是

is that Elaine and thousands,

伊莱恩和数以千计的，

or hundreds of thousands,

成千上万的

of other eels

其它鳗鱼

gather in large, intertwined masses

聚集在巨大的交错的鱼群中

and release their eggs and sperm

在一个巨大的随即交配的宴会中

in a giant orgy known as panmixia.

释放出卵和精子。

A couple of days after the eggs are laid,

在卵被产出几天后

they hatch,

它们孵化了

and the cycle begins again.

这样一个循环再一次开始了。

And because we've never seen

因为我们从未目睹过

the adult eels returning up the fresh water rivers,

成年鳗鱼回到淡水中

we must assume that,

我们必须假设

having completed their long and roundabout journey,

在完成它们长而曲折的时，

these amazing and mysterious creatures

这些神奇并且神秘的生物

finally die there,

最终消逝在了海里，

in the same place where they were born.

在它们出生的地方。

Goodbye, Elaine!

再见，伊莱恩！

It was a pleasure knowing you.

认识你是我的荣幸。