Salmon: The traveller that remembers the smell of home

A salmon's life is one of nature's most spectacular journeys. It hatches in a river, grows up in the sea, and at the end must swim upstream — even leaping waterfalls — to spawn in the very river where it was born. Let's meet this "traveller going home".

Its body

The salmon is a fish with a streamlined body built for long, fast swimming. Its muscles are powerful and its endurance remarkable, letting it fight its way up rushing currents over great distances. Species vary in size, the common ones about 60 centimetres to 1.5 metres. It wears bright silver scales, and its colour changes noticeably during migration.

How it finds its way home

The salmon's greatest skill is navigation — and it uses its sense of smell. As a juvenile it memorises the scent of its home river. When it returns from the ocean, it follows that familiar scent all the way back to where it hatched. Facing rapids and waterfalls, it leaps again and again until it clears the obstacle. The journey is so hard that many salmon die soon after spawning.

The gift it brings the forest

Migrating salmon do not only complete their own life cycle; they also carry ocean nutrients back to the forest: bears and eagles catch salmon and leave leftovers on the banks, so nutrients enter the soil and feed the riverside trees. One fish's journey, in other words, nourishes a whole forest.

A note for grown-ups

You could watch footage of salmon leaping a waterfall with a child, then talk about how it knows the way home. The answer is the smell it remembers. Showing a child that animals have navigation abilities beyond our imagination is a very rewarding lesson.