The team found that a significant number of salmon oriented themselves toward the magnetic fields that exist in their oceanic feeding grounds.
"Everybody was pretty surprised that the fish already had that ability," study co-author Nathan Putman, a researcher at Oregon State University, told Live Science. "Before the fish even hit saltwater, they already have a sense of what they should be doing if and when they should find themselves in a certain magnetic field."
Since salmon and sea turtles are so far apart on the evolutionary tree, the new findings suggest that other migratory marine animals likely have this ability as well. Two distantly related species rarely share evolutionary traits that other closer relatives don't share as well, said Putman.
Whereas many migratory bird species have the chance to learn their migratory routes from more experienced birds, young Chinook salmon don't generally have this option, because adults abandon them soon after they hatch. The inheritance of a magnetic map is, therefore, more crucial to salmon's survival than to that of other species with more adult support early in life, Putman said.