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Acoustic Tags Help Track Movement of Salmon Through Dams by Matthew Preusch The Oregonian, July 29, 2009

Researchers using tiny radio tags implanted in juvenile salmon found that an average of 76 percent of Chinook salmon survived their trip through three hydroelectric dams in the lower Snake River river last year.

(bluefish: This one year study compares to the 1994-99 average of 73 percent survival for yearling Chinook. See dampool.htm)

Researchers from the Pacific Northwest National Laboratory are sharing their findings, demonstrated in the video above, at a hydropower conference in Spokane this week. The researchers are also presenting their proposal to build a guide wall at The Dalles Dam to alter the flow of the Columbia River in order to better direct the fish, which are headed to the ocean to mature, into parts of the river where they are less susceptible to predators.

Agencies like the U.S. Army Corps of Engineers are constantly trying to upgrade or alter the big dams on the Columbia River to mitigate for the damage they do to runs of endangered salmon on the Columbia and Snake Rivers.

Pacific Northwest National Labratory

A computer-generated image shows how the proposed construction of a guide wall downstream of The Dalles Dam would alter the water's direction on the Columbia River.

While a small percentage of the migrating fish are killed directly by the dams and their spinning turbines, the concrete structures have slowed the flow of the rivers such that it makes the fish more vulnerable to predators like the northern pikeminnow.

The scientists used a computer model to predict how a new guide wall could direct the salmon to places in the river where they would be less likely to be eaten by the predators.

Related Pages:
Survival of Downstream Migration National Marine Fisheries Service, 12/21/0