CORVALLIS, Ore. – Heavy rains in western Oregon this winter have inundated grass fields in the Willamette Valley with surprising aquatic life. New research by Oregon State University and U.S. Department of Agriculture has found that flooded grass fields and drainages offer winter refuge to many kinds of fish, birds and other wildlife associated more commonly with streams than with fields.
Surveying flooded grass fields through several winters, the scientific team has identified 10 fish species, including redside shiners, sticklebacks, speckled dace and an occasional trout or Chinook salmon.
"The fish find food and shelter in these flooded backwaters then they move back into the streams as winter floods recede," said Guillermo Giannico, a fisheries ecologist with the OSU Extension Service and one of the researchers on the project.
"Flooded ditches, drainage channels and remnant wetlands mark the valley's memory of its old floodplain before the river was channeled into a single main stem generations ago," Giannico added.
Giannico and other OSU scientists have teamed up with USDA researchers, including Kathryn Boyer of the Natural Resources Conservation Service, to determine which species use the seasonal drainages and how grass seed farmers can provide good habitat for wildlife – and still produce income from their fields. In addition, the researchers are examining what these fish are eating.
"When we began our research, we thought it would be the terrestrial invertebrates that help decompose straw in the seed fields that would be washed into the drainages and eaten by the fish," said Jeff Steiner, a USDA agronomist with the Agricultural Research Service. "As it turns out, the fish are mostly feeding on aquatic invertebrates from the slow-moving drainages near fields."
Mark Mellbye, an OSU Extension agronomist, works with farmers as part of the project, using conservation practices like planting wildlife buffers and maintaining drainage and field border vegetation. Many of these practices preserve water quality. He credits local grass seed producers for their efforts at conservation and opening their farms to research. More than 25 farmers have given access to their fields to determine amounts of nutrients and sediment in their drainages, and when and where fish are found.