The whales have just returned to their breeding grounds in the shallow seas of the tropics. 座头鲸刚刚回到它的热带地区的浅海繁殖地

4. All together they constitute a mere eight percent of the world's oceans
   尽管浅水域仅仅占据了8%的海洋
5. but they contain the vast majority of it's marine life.
   不过大多数的海洋生物都生活在这里
6. A male humpback whale sings to attract a mate.
   一只雄性座头鲸正在用歌声吸引雌鲸来交配
7. The whales have just returned to their breeding grounds in the shallow seas of the tropics.
   座头鲸刚刚回到它的热带地区的浅海繁殖地
8. The calf is no more than a few weeks old.
   幼鲸才刚刚几周大
9. Despite being three meters long and weighing nearly a ton, he is nonetheless vulnerable.
   虽然已经三米长,一吨重 还是比较虚弱,也容易受攻击
10. but his mother watches over him
    不过幸好有妈妈照料

来自《行星地球 第一季 第九集 Planet Earth S01E09 海洋》第 7 行