How do salmon find their way home?
Salmon find their way back to the river where they hatched mainly by smell. They also appear to use Earth's magnetic field to navigate across the ocean.
Young salmon hatch in freshwater streams and live there for months or years before swimming to the sea. As they go, they memorize the unique chemical smell of their home stream, a process called imprinting. After one to several years at sea, adults travel back, often thousands of kilometers, to spawn.
Studies suggest salmon use Earth's magnetic field to find the general area of their home river along the coast. Once near the right river, they follow its scent upstream, choosing the correct branches at each fork. They leap waterfalls and swim against strong currents.
The final journey
Most Pacific salmon species die soon after spawning, and their bodies provide nutrients for the river, forests and wildlife like bears and eagles. Atlantic salmon can survive and return to spawn more than once. Dams and habitat loss have made these journeys harder.
Did You Know?
Some salmon in the Yukon River swim more than 3,000 kilometers upstream to reach their spawning grounds.