When it’s time to spawn, salmon have an uncanny ability to swim from the middle of the Pacific Ocean in almost a straight line directly back to the mouth of the river where they were spawned and make their way upstream.
The mystery of this unflappable internal GPS system has fascinated ichthyologists for centuries.
But now there may be an answer: The fish have tiny magnets in their flesh that allow them to use the Earth’s magnetic field as both a map and a compass, according to new research unveiled last month.
For California, the findings could have positive ramifications for the state’s struggling commercial and recreational salmon fishing industry. In recent years, state and federal officials have relied more and more on fish raised in hatcheries that are hauled downriver via boat or in a truck. The hauling somehow throws salmon GPS systems out of whack.