Though their immediate ancestors were fish raised in hatcheries, wild-born Snake River sockeye are once again completing their impressive voyages, the National Oceanic and Atmospheric Administration announced Monday. "This is a real American endangered species success story," said Will Stelle, an administrator of NOAA's fisheries, in a statement. "With only a handful of remaining fish, biologists brought the best genetic science to bear and the region lent its lasting support."
Sockeye and most other salmon species are born in freshwater, and then head to the salty ocean to grow fat. These fish make a return at the twilight of their lives to lay and fertilize the next generation in the same areas where they were born. How salmon - born either in hatcheries or in the wild - know how to make it to the ocean from their freshwater birthing grounds is one of nature's greatest mysteries. As ichthyologists at the U.S. Geological Survey write, "it must be a genetic clue," but how those genes guide the salmon to the sea is still anyone's guess.