By Patricia Waldron, Science Magazine, February 6, 2014
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| Chinook Salmon |
Despite having no life experience, young salmon in the Pacific Northwest somehow travel hundreds or thousands of kilometers from their native streams to feed and grow in the ocean. While they can use their sense of smell to get back home to spawn, Chinook salmon (Oncorhynchus tshawytscha) have an inborn sense of direction that functions like a GPS. Scientists now suspect that with no prior knowledge, they use Earth’s magnetic field to find the right ocean habitat. To make the discovery, researchers placed hatchery-raised juveniles inside a bucket and exposed them to artificially generated magnetic fields. When the angle and intensity of the field matched the southernmost part of their ocean range, the fish oriented themselves to face north or northeast. The magnetic field at the northernmost range caused them to point south or southwest. By orienting within these two extremes, the salmon can find the feeding grounds of their ancestors, the team reports today in Current Biology. Because sea turtles use a similar magnetic map, the researchers speculate that many migratory marine animals, such as eels, sharks, and seals, may also navigate using magnetic fields.
Humans have a small amount of the mineral magnetite in our brains that give us an innate sense of direction (we can sense the Earth's magnetic field too!) But this sense becomes scrambled by the many electromagnetic fields we are exposed to everyday (especially those anti-theft things we walk through before we leave the store).
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