Scientists Unravel Mystery Of How Sea Turtles, Salmon Cross Thousands Of Open Ocean Miles To Go Back Home Again

December 2, 2008 12:47 p.m. EST

Chapel Hill, NC (AHN) - They can't click their heels together and they don't wear ruby slippers, but sea turtles and salmon feel the same way about their homes as Dorothy in The Wizard of Oz felt about hers, there's no place like home and they will migrate thousands of miles across open ocean to get back.

Scientists think they have unraveled the secret to how marine animals find their way back home to their birthplaces. They say that young salmon and sea turtles can detect the distinctive "magnetic address" of their birthplace and navigate back to it.

University of North Carolina at Chapel Hill scientists theorize that salmon and sea turtles may begin their lives by reading the magnetic field of their home area, and in some way imprint it in a way that allows them to make their way back home later.

The earth's magnetic fields vary in a predictable way across the earth with with every oceanic region having a slightly different magnetic signature, scientists say. Earlier studies had already found that young salmon and sea turtles could detect those magnetic fields and use it to sense direction as they migrated away from their birth places.

This study focused on figuring out how adult salmon and sea turtles navigated their way back home using this natal homing process.

"What we are proposing is that natal homing can be explained in terms of animals learning the unique magnetic signature of their home area early in life and then retaining that information," Kenneth Lohmann, Ph.D., professor of biology in the UNC College of Arts and Sciences and the first author of the study, said in a statement. "We hope that the paper will inspire discussion among scientists and eventually lead to a way of testing the idea."

Sea turtles often spend a decade and thousands of miles away from home before returning while salmon are born in rivers, migrate out into oceans and return to the river place where they were born to reproduce.

Findings are printed in the latest issue of the journal Proceedings of the National Academy of Sciences.