Salmon have a built-in GPS powerd by Earth’s magnetic field


The State Column, | February 07, 2014

Salmon have a built-in GPS powerd by Earth’s magnetic field

Chinook salmon’s means of finding their way to food is inherited, not learned


It turns out young salmon don’t just learn quickly, they don’t need to learn at all. A study out of Oregon State University finds that juvenile Chinook salmon are born knowing the route to their ancestral feeding grounds, and use Earth’s magnetic field to navigate. That’s the equivalent of dropping a child off in the middle of nowhere and expecting them to find the nearest McDonald’s using nothing but a compass.

While lots of animals navigate using Earth’s magnetic field, the salmon are the only animals besides loggerhead turtles to be born with an innate set of turn-by-turn directions. For migratory animals, the routes must be learned by following adults during adolescence, internalizing the associated magnetic fields as they go.

To test the theory, researchers placed hundreds of juvenile Chinook salmon in test tanks. When they manipulated the magnetic field using electromagnetic coils, they found that a significant number of them oriented themselves towards the magnetic field that corresponded with their oceanic feeding territories.

“Everybody was pretty surprised that the fish already had that ability,” study co-author Nathan Putman, a researcher at Oregon State University, told Live Science. “Before the fish even hit saltwater, they already have a sense of what they should be doing if and when they should find themselves in a certain magnetic field.”

Given that it’s rare for species like turtles and fish (who are worlds apart on the evolutionary tree) to share a trait like this, researchers are inclined to believe that other migratory marine animals possess the ability as well.

It’s suspected that the salmon’s innate sense of direction is less a superpower and more a matter of necessity – whereas birds can map out routes by following their elders, salmon quickly abandon their young and leave them to fend for themselves. Without a way to know where they need to go to find food, they’d starve.

The next step in the research is to determine the precision of the salmon’s internal GPS, whether it can get them within miles or inches of their feeding grounds. The researchers suspect that while their instrument is probably rough in adolescence, it likely improves over time with practice and age.

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