Here, as Mara weakens from lack of food, Kell grows stronger by the day.

在这里，当玛拉因为食物缺乏而虚弱时，凯尔日渐强壮。

Soon he will be strong enough to leave her side.

不久它将强壮到足以离开母亲的身边。

A whale's tail does not just identify, it is the key to its survival.

鲸的尾巴不仅用来辨别身份，也是生存关键。

It powers the swim. It wards off predators. It will even help it fish.

它提供游泳的动力，抵御猎食者，甚至可以帮助它捕鱼。

When Mara was young another whale began using his tail to fish.

当玛拉还小时，另一头鲸开始用尾巴捕鱼。

Till then his family had only caught fish with bubbles.

在这之前，它的家人只会利用气泡捕鱼。

Their prey were fast swimming herring.

它们的猎物是游速很快的鲱鱼。

But when the herring disappeared, the whales found slower, less agile fish.

但当鲱鱼消失，鲸鱼们发现游速较慢，不很敏捷的鱼。

They didn't need to be rounded up with bubbles. So this humpback did something new.

它们不需要使用气泡围住这些鱼。因此这头座头鲸做了件新鲜事。

He swam above the fish shoal, and then...he slapped the water, killing or stunning the fish...

它游到鱼群上方，然后拍打着水，将鱼杀死或打昏......

He discovered that by tail-slapping he could have an easy meal.

它发现用尾巴拍打就能轻松有一顿大餐。

Soon other whales began fishing this way too, especially the younger, faster learners.

不久，其它座头鲸也开始用这种捕鱼方法，特别是幼鲸学得更快。

This is what makes humpbacks special...

这是座头鲸与众不同之处......

When they need a new technique to catch their prey they can invent one.

当需要新技术来捕猎时，它们就发明一个。

Humpbacks now face a new danger when hunting fish, from which escape is often impossible.

座头鲸现在面临一个新危险，往往难以逃离。

Humans hunt fish too, with nets and ropes so strong they can entangle a whale.

人类也捕鱼，人类的渔网与鱼绳牢到可以缠住鲸鱼。

More humpbacks die entangled in fishing gear than any other way.

死于缠住渔具的座头鲸比其他方式都多。

The nets and ropes are tough and long-lasting.

渔网和鱼绳坚韧且寿命长久。

They cling, they capture...they can entangle the mouth, flippers and tail...making swimming and feeding impossible. They also kill.

它们紧紧抓住不放，缠住它们的嘴、鳍足和尾巴，使其无法游泳和进食，也能杀死它们。

Most humpbacks have scars from fishing gear.

多数座头鲸身上有渔具造成的伤痕。

A single rope can kill a whale. It can wrap around the mouth, rip apart the baleen.

一条鱼绳就能杀死一头鲸鱼。鱼绳可以缠绕嘴巴、撕裂鲸须。