Otter mothers usually produce one or two cubs at a time.

Triplets, like these, are extremely rare.

And each cub needs to eat 1/4 of its body weight every day.

(otter grunting) So this mother has to catch a lot of food.

(water splashing) (otter grunting) She must also feed well herself if she's to survive the winter.

The youngsters squabble over every fish.

(otters grunting) The biggest and most vigorous cub is the first to get food, and the smallest often goes hungry.

(otters grunting) This small male, however, decides to fish for himself, and joins his mother farther out to sea.

He's caught something.

Unfortunately, it's something that bites back.

(otter groaning) It's a crab, which is easy to catch but not very nutritious.

His mother has been too busy to notice that he has strayed.

(otter squeaking) And now he is lost.

Over a quarter of otter cubs don't survive their first year.

Many because they lose touch with their mothers.

All he can do is to keep calling.

(otter grunting) (otter squeaking) (otter grunting) (otter squeaking)