Without any prior migration experience, juvenile Chinook salmon can find their way to ancestral feeding grounds by using the Earth's magnetic field and an inherited internal map, according to a new study. Lots of migratory animalsuse the Earth's magnetic field to orient themselves during migrations. But in most known cases, young animals learn routes from more experienced individuals, and then internalize the magnetic fields associated with those routes for subsequent trips. Until now, loggerhead sea turtles have been the only animals confirmed to know ancestral migration routesfrom the moment they hatch. But now, researchers based at Oregon State University have found that juvenile Chinook salmon — which hatch in freshwater streams and then swim to the ocean to feed within the first year of their lives — also inherit a sense of direction to their families' migration routes. [Quest for Survival: Incredible Animal Migration] The researchers tested the internal maps of hundreds of juvenile salmonby placing individuals in test tanks, letting the fish acclimate for about 10 minutes and then manipulating the magnetic field around the tank using coils with electric currents running through them. 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." The study findings are detailed Thursday (Feb. 6) in the journal Current Biology.
/ Source: Live Science