ARS | Publication request: GRASS SEED FIELDS, SEASONAL WINTER DRAINAGES, AND NATIVE FISH HABITAT IN THE SOUTH WILLAMETTE VALLEY

Submitted to: Seed Production Research at Oregon State University
Publication Type: Experiment Station
Publication Acceptance Date: March 31, 2004
Publication Date: April 30, 2004
Citation: Steiner, J.J., Mellbye, M.E., Griffith, S.M., Giannico, G.R., Li, J., Boyer, K.S., Schoenholtz, S.H., Whittaker, G.W., Mueller Warrant, G.W., Banowetz, G.M. 2004. Grass seed fields, seasonal winter drainages, and native fish habitat in the South Willamette Valley. Seed Production Research at Oregon State University. Corvallis, Oregon. p. 55-56.

Interpretive Summary: Winter seasonal drainage channels move more than 84-billion gallons of water that pass over grass seed fields in the Willamette Valley in western Oregon. These drainages are dry in the summer, but during the winter provide shelter and food to a large number of native fish and amphibian species. We are determining how and where native aquatic wildlife utilize these winter seasonal streams, what the nutrient concentrations are in the water moving through these drainages when aquatic animals are present, and finding out how grass seed farm management and conservation practices may be managed to increase aquatic wildlife use. Our results are showing that winter drainages not only provide seasonal shelter to various native species of fishes when flows in the river main stems are high, but also that some of these species may even reproduce and find nursery habitat in such drainages. In addition, we are finding that the invertebrates that inhabit these seasonal water bodies constitute an important component of the spring diets of some of these fish species.

Technical Abstract: We are in the third year of a study determining how and where native aquatic wildlife utilize winter seasonal streams that drain grass seed farms in the southern Willamette Valley. We are also finding out what the nutrient concentrations are in the water moving through these drainages when aquatic animals are present. Both native fish and amphibians utilize agricultural drainages as winter habitat for refuge and reproduction. Ninety-eight percent of the fish and amphibians caught were native species. Nitrate- and ammonium-nitrogen (N) concentrations were generally below what are referred to as the lowest observed adverse concentrations (LOAC) when aquatic wildlife is present. The average nitrate- and ammonium-N concentrations when aquatic animals were present were 4.2 and 0.23 ppm, respectively. Stomach contents of captured fish species indicate most of the invertebrates consumed by the fish are fresh water crustaceans, with a smaller component of the diet consisting of aquatic insects. Few terrestrial originating invertebrates are found in the seasonal drainage channels.