A new study from a team OSU researchers, led by Nathan Putnam, recently published in the February 6th edition of Current Biology finds that steelhead and salmon use magnetic field-based internal maps to find their way back to their natal streams to spawn.

James Gould, an evolutionary biologist at Princeton University who was not involved in the study, wrote in a commentary on the paper that the fish may not have a map like the kind we might imagine, but instead something akin to an Excel spreadsheet, with “lists of magnetic coordinates with the seasonally appropriate directional responses filled in.” That is, the fish may simply perceive the magnetic field at a given location and, like a GPS, have essentially a voice command in its head that tells it where to swim. Putman thinks this is likely the case for the salmon. “If I had to bet, I would say that is probably what’s happening,” he says.

For a writeup of the study, see Scientific American online.  For the full study, click here.