Nearly half of newly hatched salmon die as they run to the ocean. Understanding how water flows around dams may improve their odds.
Spring is precarious for young salmon in the Pacific Northwest.
From their nurseries in the mountain tributaries of the Columbia and Snake rivers, they are driven by instinct and warm spring temperatures to dash to the ocean. Many are no bigger than a baby's thumb, yet they cover 500 to 1,000 miles over two months. Nearly half die along the way from exhaustion, disease, pollution, and predation, aggravated by the aftereffects of passing through dams and plunging over spillways. These fatalities are disheartening to Larry Weber, a hydraulic engineer from, of all places, central Iowa. Larry Weber, an environmental engineer at the Iowa Institute of Hydraulic Research at the University of Iowa, poses on a scale model of 5,000 feet of the Columbia River in the state of Washington.