This ready-to-spawn sockeye salmon began life here, in the shallow headwaters of British Columbia's Adams River. It grew from a newly hatched alevin, to a tiny fry, to a smolt that found its way to salt water, then an adult roaming the Pacific Ocean. Now, after perhaps half a dozen years at sea, it has found its way back to its spawning ground. Here it will lay its eggs, then die. It's a struggle to return upstream, and at each stage it faces risks—predators, pollution, habitat loss and more.