A new fly that salmon like to eat is discovered, right here in river city.
Tiny fly is why salmon thrive in Yolo Bypass, scientists say
By Matt Weiser - mweiser@sacbee.com
Published 12:00 am PDT Thursday, May 1, 2008
The Sacramento Valley is a well-used landscape. After 160 years of mining and urbanizing, plowing and diverting, you'd think the environment would have given up all its secrets.
But a trio of local scientists recently unlocked a mystery about why young salmon grow faster during floods in the Yolo Bypass, and in the process they identified a new species.
Ted Sommer, a senior environmental scientist at the state Department of Water Resources, discovered about eight years ago that juvenile chinook salmon grow faster and fatter when the bypass floods. This vast flood corridor between Sacramento and Davis seemed to be an important feeding area for salmon – when floods allow them to swim into it.
"They grew like gangbusters, often twice as fast as fish that stayed out in the river," he said.
But nobody knew what the salmon were feasting on or where the food came from.
To answer that question, Sommer put an intern on the trail. Gina Benigno, then a recent UC Berkeley biology graduate, spent the winter of 2004-2005 taking samples in the bypass: water from ponds, water flowing into the bypass from creeks and drains, and the soil itself.
The dirt went into big plastic bins in a lab at UC Davis. She flooded the dirt with water and covered the bins with screens. And then she waited.
Within a few days, insect larvae hatched in the water and the bins were buzzing with adult flies.
Sommer and Benigno couldn't identify them, so they sat down with Peter Cranston, an entomology professor at UC Davis.
It took Cranston only minutes of squinting through a microscope to provide an answer. And it was he who came away most surprised.
Cranston is one of the world's leading experts on chironomids, a family of gnatlike, non-biting aquatic flies also known as midges. He travels the world hunting for new chironomids, but never expected to find one in his own backyard.
He and Benigno co-authored a paper last year identifying the bugs from the Yolo Bypass as a new species.
