How do spawning fish navigate back to the very same stream where they were born?: Scientific American

How do spawning fish navigate back to the very same stream where they were born?: Scientific American: "How salmon return to the correct shore�line region is not completely understood. It appears they use some form of “map and compass” navigation based on information about position and direction of travel. This information most likely comes from a suite of environmental cues, including day length, the sun’s position and the polarization of light that results from its angle in the sky, the earth’s magnetic field, and water salinity and temperature gradients. Whatever the specific mechanism, as spawning time approaches, salmon have a seemingly inherited tendency to orient themselves toward the area of coastline where their natal waterway discharges."