Sharks use Earths magnetic field as a GPS, scientists say Published On Sharks use Earths magnetic field as a GPS, scientists say PORTLAND, Maine (AP) — Sharks use the Earth’s magnetic field as a sort of natural GPS to navigate journeys that take them great distances across the world’s oceans, scientists have found. Researchers said their marine laboratory experiments with a small species of shark confirm long-held speculation that sharks use magnetic fields as aids to navigation — behavior observed in other marine animals such as sea turtles. Their study, published this month in the journal Current Biology, also sheds light on why sharks are able to traverse seas and find their way back to feed, breed and give birth, said marine policy specialist Bryan Keller, one of the study authors.