A permeability study on salmonid spawning areas in northern Humboldt County, California

Abstract

This research was conducted to determine if local salmonid, specifically coho salmon (Oncorhynchus kisutch), Chinook salmon (O. tshawytscha), and the steelhead trout (O. mykiss), redd location is dependent upon the permeability of the streambed. The study took place at four study sites in two coastal drainages in northern Humboldt County, California over a 16 month period (June 2004 to October 2005). This period covered pre and post spawning conditions, as well as changes in seasonal flow conditions. Sampling grids were established at each site to allow for repeatable permeability measurements which ranged in number from 37 to 105. Permeability measurements were taken using a battery operated pump to draw water through a perforated standpipe driven into the streambed at a depth of approximately 25 cm. Study results showed that permeability was not significant in predicting redd location. In addition, results showed that permeability measurements varied in orders of magnitude within as little as 30 cm. Graphic representations of the spawning areas were created using GIS and clearly display the heterogeneity of the streambed. The results of this study support the need for further investigation of spawning gravel assessment methods which can account for extreme spatial variation while minimizing disturbance to the streambed.

Parent Publication

• Proceedings of the coast redwood forests in a changing California: A symposium for scientists and managers

Citation

Knopf, Claire. 2012. A permeability study on salmonid spawning areas in northern Humboldt County, California. In: Standiford, Richard B.; Weller, Theodore J.; Piirto, Douglas D.; Stuart, John D., tech. coords. Proceedings of coast redwood forests in a changing California: A symposium for scientists and managers. Gen. Tech. Rep. PSW-GTR-238. Albany, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture. pp. 427-435.