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Synthetic Salmon School Swims for Science

by Mike Lee
Tri-City Herald, November 30, 1999

A squadron of synthetic salmon makes its maiden voyage Wednesday, hurtling through the bowels of Bonneville Dam as a band of fearless droids.

They are the eyes and ears of Pacific Northwest National Laboratory scientists faced with the daunting challenge of recording how fish feel as they are washed through the region's power-generating turbines.

Some will pay with their electronic lives.

"Just like real live fish ... some of them will get whacked," said Tom Carlson, a PNNL scientist in Portland. "We are expecting a 'mortality' of these fish on the order of about 10 percent."

That's a greater kill rate than real fish - but Carlson's version is comparatively rigid and the electronic gizmos on board are fragile.

The Army Corps of Engineers has deployed real chinook - albeit with no small amount of technical appendages - for the last two weeks in an experiment to see how fish fare going through new-design turbines. The Kaplan "minimum gap runners" are designed to reduce the places where fish are likely to be injured by the massive spinning turbine blades. That experiment relies on biologists interpreting the bumps and bruises on 6-inch chinook after they pop out of the dam.

PNNL is taking another approach at Bonneville, which is being retrofitted over the next decade with new turbines that eventually may be installed throughout the Columbia River system.

"You can simulate the conditions in those turbines, but there is no way of knowing what is happening for sure," said Staci Maloof, spokeswoman for PNNL, which is operated by Battelle.

The rubber fish - modeled after real spring chinook smolt - record pressure, acceleration and strain as they descend into the underwater world.

"What we really want to learn about is severe hydrologic events - sheer or turbulence - both of which have negative effects on real live fish," Carlson said. "We also want to know when the body strikes something or is struck by something."

Just as important as the obvious outer changes are not-so-evident dangers of hydro passage, such as disorientation and stunning that can make young salmon easy bait for waiting predators even if they survive the blades.

It's hoped better information about what fish face inside the dams will lead to changes that will decrease fish injury and mortality. Improvements at all the dams on the Columbia and Snake rivers could potentially save millions of fish and reduce the benefits from taking out the dams between Pasco and Lewiston

The Battelle fish are comprised of a rubber outer coating stuffed with a battery and seven sensors and rigged with balloons to lift them to the surface once they escape the turbine.

The fish are silvery green, but plans are to paint them Coast Guard orange to ease retrieval. Battelle, operating on grants of more than $500,000, tested its crash salmon in April at McNary Dam, then upgraded the fish for the Bonneville tests.

Once done there, the fish are up for more improvements for another round of tests, perhaps to better understand what happens to fish as they spill over the top of the dams during high spring flows.

by Mike Lee
Synthetic Salmon School Swims for Science
Tri-City Herald, November 30, 1999

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