During the past dozen or so years, OSU scientists have been using telemetry to study survival rates of juvenile salmon below Bonneville Dam. They discovered a high rate of mortality in the estuaries, which led to the surprising discovery of the impact of predation from colonies of terns. In 2000, OSU introduced the use of a new tool acoustic telemetry for studying salmon on the West Coast. Acoustic telemetry allows the signals emitted from tagged fish to be picked up by underwater hydrophones in salt water, as well as fresh.
A team led by David Welch, a British Columbia scientist and lead author of the PLoS paper, subsequently established a series of listening stations along the continental shelf, and also began using the same acoustic technology used by OSU researchers to study the survival of smolts in the Fraser River.
Comparing smolt survival from one river system to another is complex, because there can be a huge difference in the overall "quality" of smolts even before they begin their long journey to the Pacific Ocean, according to Shaun Clements, a biologist with the Oregon Department of Fish and Wildlife and co-author of the study, who conducted some of the tagging studies.
Clements, a former senior research associate at OSU, said the health and fitness of the smolts that are captured at the Columbia River's Lower Granite dam varies significantly.
"One day, we'd get a group of fish that were released from one hatchery and they'd be relatively weak, then a few days later we'd get a bunch of fish from a different hatchery and they would be robust," Clements said. "Hatcheries weren't the only variable s
|Contact: Carl Schreck|
Oregon State University