Oregon Coast Scientists Find Link Between Magnetic Field and Fish
(Corvallis, Oregon) – Groups of scientists connected with OSU in Corvallis and parts of the central Oregon coast have released findings that there is indeed a correlation between the migration patterns of ocean salmon and the Earth's magnetic field. This discovery helps explain how these fish seem to find their river of origin across thousands of miles of water.
Researchers from the Oregon Hatchery Research Center in the Alsea River basin and Oregon State University’s Department of Fisheries and Wildlife conducted the study, which was funded by Oregon Sea Grant and the Oregon Department of Fish and Wildlife.
Scientists exposed hundreds of juvenile Chinook salmon to different magnetic fields that exist at the two extremes of their range of travel. They responded to what scientists called “simulated magnetic displacements” by swimming in the direction that would bring them toward the center of their marine feeding grounds.
“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 Nathan Putman, a postdoctoral researcher in Oregon State University’s Department of Fisheries and Wildlife and lead author on the study.
“These fish are programmed to know what to do before they ever reach the ocean,” he added.
The experiment process included a large platform with copper wires running around its edges, the means by which researchers could control the magnetic field in a variety of ways. The two-inch juvenile salmon were placed in five-gallon buckets. When encountering magnetic fields with the characteristics of their northern oceanic limits, they were more likely to swim in a southerly direction – and vice versa.
What scientists discovered was that fish are born with a “map sense” determining where they are and which way to swim based on the magnetic fields they encounter.
While the evidence is considered solid, not all the fish responded in the same way to the field manipulation. Still, it did not take much for the salmon to detect the fields and react to them as the fields were not even strong enough to sway a compass needle.
“I tell people: The fish can detect and respond to the Earth’s magnetic field. There can be no doubt of that,” said co-author David Noakes of OSU, senior scientist at the Oregon Hatchery Research Center and the 2012 recipient of the American Fisheries Society’s Award of Excellence.
The sensitivity to these fields brings up larger questions about salmon and other magnetic sources around them, such as those at hatcheries or when they encounter dams.
“When they reach the ocean, they may swim by structures or cables that could interfere with navigation,” Noakes said. “Do these have an impact? We don’t yet know.”
The magnetic field is likely not the only tool salmon use to navigate, however, Putman noted.
“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,” Putman said.
The study involved about 1,000 fish and was conducted at Alsea, Oregon, near Waldport – close to the central Oregon coast.
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