原文视听

But with hundreds of thousands of fish crammed into the shallows,
不过浅水域挤了几十万条鱼
the sharks now need only rely on their speed and agility.
鲨鱼靠速度和灵活身手即可得逞
As the first shark starts to hunt in earnest,
第一条鲨鱼开始痛下杀手
a feeding frenzy breaks out.
一阵疯狂的吞噬就此展开
The shoal's defences are weakened,
沙丁鱼群的防卫减弱
there isn't enough space to manoeuvre.
狭隘的空间让它们施展不开
And the sharks can gorge themselves.
鲨鱼大可以狼吞虎咽
Despite the casualties,
尽管死了不少沙丁鱼 但鱼群为数众多
the shoal is so vast that the sharks have little effect on its size.
鲨鱼几乎没有影响鱼群的规模
Fish not only come together in great shoals for defence,
鱼儿成群结队不只是为了防卫
but at other critical times in their lives,
也为了应付生命中其他关键时刻
when they're ready to spawn.
就是它们准备产卵的时候

重点解释

But with hundreds of thousands of fish crammed into the shallows,不过浅水域挤了几十万条鱼

cram into勉强塞入,填满

How do they all cram into that doll's house?

那小小的房子怎麽挤得下他们大家呢?

We all managed to cram into his car.

我们大家好歹都挤进了他的车。

the sharks now need only rely on their speed and agility.鲨鱼靠速度和灵活身手即可得逞

rely on依靠；信赖

Don't rely on his memory， he's a bit of a dreamer.

不要相信他的记忆力－－他有点神不守舍的。

He grew increasingly to rely on her.

他越来越依赖她了。

a feeding frenzy breaks out.一阵疯狂的吞噬就此展开

break out（战争、火灾等）爆发

A quarrel broke out between them.

他们间爆发了一场争吵。

It appears as if a war will break out.

看来一场战争似即将爆发。

when they're ready to spawn.就是它们准备产卵的时候

be ready to随时可, 乐意, 即将

The potatoes are ready to be dug up.

快要收获土豆了。

He packed up and was ready to go.

他整理好行装准备出发。