How Salmon Find Their Way Home

News ID: 278282 Service: Science
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TEHRAN (Tasnim) – Ever wondered how salmon manage to swim hundreds of miles upstream, back to the exact spot where they were born?

They’re not secretly geniuses; a recent study slated for publication in the journal Current Biology confirms a link between salmon migration and the earth’s magnetic field.

"People have really not understood the salmon migration for a long time," co-author David Noakes said.

In the past, scientists have guessed that the phenomenon might have something to do with the sun, the moon, or even the stars. Nope. “This is the first time anyone has demonstrated it was magnetism,” Noakes said.

Noakes and other researchers came to the conclusion through a series of experiments at the Oregon Hatchery Research Center. Scientists filled buckets of water with hundreds of tiny Chinook salmon, exposing them to magnetic fields of specific direction and strength that are typical of what exists in the wild.

Scientists had an “A-ha!” moment when fish placed in magnetic fields similar to those found in the northern end of their habitats tended to swim south, and vice versa.

Noakes believes the earth’s natural magnetic field may be at play in other (super cute but not that smart) migratory species, such as sea turtles. ”In principle, if you had to use some way to find your way around a big ocean, magnetism is a good way to do it,” Noakes explained. “It doesn’t change very much. “It doesn’t depend on night or day.”

And the finding has implications other than just being totally cool. Hatcheries often release salmon into the wild, but Noakes said these salmon don’t perform as well as fish that were born wild. That’s probably because hatcheries are usually surrounded by electrical wires, which disrupt the magnetic fields that guide salmon.

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