Pacific Salmon Born with Magnetic Map for Thousand-Mile Migration

Further evidence suggests that Pacific salmon posses an inherent "magnetic map" that guides them through their thousands of miles of migration. Interestingly enough, their migration is scientifically known as one of nature's greatest.

A Pacific salmon's journey begins when it hatches in inland rivers and streams. This journey continues when it swims hundreds--and sometimes thousands--of miles to the ocean. Now, researchers have found that the salmon may detect changes in the intensity and angle of the Earth's magnetic field, which allow them to determine if they are in or near their desired location.

The lead author of the study, entitled "An Inherited Magnetic Map Guides Ocean Navigation in Juvenile Pacific Salmon," is Dr. Nathan Putman of Oregon State University. The study was published today in the journal Current Biology.

"The migration is a lot of effort and it is definitely challenging, and looking at it from the outside, it doesn't seem necessarily intuitive how they could manage that," said Dr. Putman in this BBC article.

Previous studies found that the Sockeye salmon retains memories from the magnetic field that it encountered when it first entered the ocean after coming from the mainland. Yet this latest study reveals that salmon may wield an even greater sense of the Earth's magnetic field.

The researchers placed the salmon in buckets in order to examine their ability to react to magnetic currents. These fish had never before made a migration. The magnetic field was then manipulated around areas of the bucket to gauge the fish's response to change. In the end, the researchers found that when they altered the magnetic field to serve as the northern extreme of the salmon's range, the fish went south. And vice-versa.

Since the fish reacted the way they did, it's likely that Pacific salmon are born with an inherent magnetic sense.

If you'd like to take a look at the entire study, please visit this issue of Current Biology.