New research supports the theory that salmon use the earth's electromagnetic fields to navigate across the oceans. Researchers from Oregon State University published the findings yesterday in Current Biology.
Previous research found a correlation between magnetic fields and salmon migratory patterns. To further test this theory, researchers at the Oregon Hatchery Research Center observed the effects of different magnetic fields on juvenile Chinook salmon. They found that the fish re-oriented themselves to swim towards the center of their feeding grounds, indicating that they use magnetic fields to find their way.
"What is particularly exciting about these experiments is that the fish we tested had never left the hatchery and thus we know that their responses were not learned or based on experience, but rather they were inherited," lead author Nathan Putman said in a statement. "These fish are programmed to know what to do before they ever reach the ocean."The fish are quite sensitive to these magnetic pulls, which makes sense because the Earth's fields are relatively weak. Putman said the magnetic fields used in the test were "not even strong enough to deflect a compass needle."
What does this mean for fish in the wild, who are regularly exposed to strong magnetic fields from man-made structures like electrical cables or power dams? We don't know yet. It's likely that this isn't a fishes only tool that acts as a GPS, said Putman. "They likely have a whole suite of navigational aids that help them get where they are going, perhaps including orientation to the sun, sense of smell and others."