It's no secret that
strong magnets are capable of some pretty awe-inspiring things. From the
bar magnets that help your computer's hard drive to spin to the
rare earth magnets in the motors of cordless tools, they boast a wide variety of capabilities.
Did you know, though, that magnetism may help to explain an epic natural phenomenon? For years, researchers have been trying to explain the
migration patterns of ocean salmon. Now, a new study suggests that these fish are able to navigate thousands of miles and find their river of origin by responding to the Earth's magnetic field.
A Miraculous Journey
After salmon hatch in rivers and streams, they swim distances of hundreds or even thousands of miles to make their way into the ocean. Several years later, though, they make their long trip back to freshwater to spawn and eventually die. So the question is: How do they know their way there and back? BBC News reported that a study recently published in the journal Current Biology revealed that Pacific salmon may have
an innate magnetic map that allows them to make their long journey without getting lost. This means that the
fish are able to detect changes in the Earth's magnetic field, such as in the angle or intensity, to determine their
location in the water.
A Surprising Explanation
To arrive at these conclusions, the Oregon State University researchers observed Chinook salmon hatchlings that had yet to migrate to sea. The team exposed the fish to a variety of different kinds of magnetic fields they would encounter on their long journey. These ranged in intensity, as do the
magnetic fields in the Earth depending on location. Dr. Putnam noted that miraculously, after placing the salmon in buckets and altering the magnetic field around them, the fish would respond by changing direction. If the team adjusted the field so that it resembled the northern tip of the salmon's range, the fish pointed north. On the other hand, if researchers changed the field so that it mimicked the southern end of their range, the salmon turned around to face north.
Dr. Nathan Putman, who led the study, had previously conducted research that suggested Sockeye salmon may memorize where they first entered the ocean based on the magnetic field, and then use that memory to navigate back to their spawning site. The latest report, though, indicates that fish may just be born with an intuitive sense of the Earth's magnetic field.
"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," said Putman, as quoted by Science 2.0. "These fish are programmed to know what to do before they ever reach the ocean."
Room For Research
Putman also noted that the salmon were only exposed the magnetic field the team created for eight minutes, and the field wasn't even strong enough to move a compass needle. As the Earth's magnetic field is relatively weak, Putnam believes the fish are especially sensitive to it. However, salmon likely use a host of other navigational aids beyond the magnetic field, such as the sun and their sense of smell. There are other aspects of the salmon's life cycle to take into account as well.
"Fish are raised in hatcheries where there are electrical and magnetic influences, and some will encounter electrical fields while passing through power dams," explained co-author and senior scientist David Noakes, as quoted by Nature World News. "When they reach the ocean, they may swim by structures or cables that could interfere with navigation. Do these have an impact? We don't yet know."
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