Salmon Can Locate Their Birth Rivers After Years in the Open Ocean

There’s no place like home, even for fish. That’s especially true of salmon, who return to the freshwater stream where they were born after years — and thousands of miles traveled — in the open ocean. They do so not out of sentimentality (though it’s nice to imagine they enjoy their homecomings) but to reproduce in the exact stream where they themselves first entered the world. 

Though scientists aren’t entirely sure how salmon manage this incredible feat, most believe it’s through a combination of their highly evolved sense of smell and by using the earth’s magnetic field like a compass. By the time they leave their natal stream, salmon have imprinted the precise taste and smell of the water, and they use that sense-memory to return to the same spot years later. Salmon also have tiny crystals of magnetite, an iron-based mineral, in their heads that enable their magnetic perception. If they could also evolve the ability to stop jumping directly into bears’ mouths, they could just be unstoppable.