Friday July 14, 2023

Smithsonian Magazine

Of all the traits that make salmon extraordinary migrants—their leaping prowess, their tolerance of both fresh and salt water, their attunement to the Earth’s magnetic fields—the most impressive might be their sense of smell. Guided by the odors they imprint on in their youth, most adult salmon famously return to spawn in the stream where they were born. No one knows precisely what scents young salmon memorize, but it’s probably some combination of mineral and biological signals, such as distinctive metals and the smell of their own kin.

Several years from now, however, if scientists at the Oregon Hatchery Research Center have their way, some chinook salmon will be chasing a very different scent: the rich, beery bouquet of brewer’s yeast. The alluring aroma of ale is a bid to solve a sticky conservation conundrum: How do you get hatchery-reared salmon to come home?

Though the vast majority of salmon return to their birthplace to spawn, they sometimes slip up. A small portion naturally stray into other streams. “From an evolutionary standpoint,” says Andy Dittman, a Seattle-based biologist at the U.S. National Oceanic and Atmospheric Administration, “it’s an important alternative strategy” that helps populations survive disaster and expand their range.

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