Jacobs, 2002

Jacobs, S. E. 2002. Calibration of estimates of coho spawner abundance in the Smith River basin, 2001. Oregon Department of Fish and Wildlife, Monitoring Program Report Number OPSW-ODFW-2002-06, Portland, Oregon.

Estimates of coho spawner abundance derived from spawning surveys are a fundamental component of the Oregon Department of Fish and Wildlife’s (ODFW) Oregon Plan Monitoring (Jacobs et al. 2001). The basis of these estimates are visual counts of adult spawners in randomly selected stream reaches. To date, survey-derived estimates have not been validated against known spawner abundances. Beginning in 1999, we initiated a study at Smith River (Umpqua Basin) to calibrate survey-based spawner estimates. Smith River provides an ideal location for this type of study because it is typical of many other coastal streams that support coho salmon, contains large quantities of habitat and spawners, and provides the ability to efficiently trap and tag adequate portions of the coho run. The objective of this study is to compare survey-based estimates to rigorous estimates derived from trapping and tagging coho at Smith River Falls. This document reports results obtained for the 2001 run year and discusses the implications of these results and the results obtained for the two prior years to the accuracy of coastal spawner abundance estimates.