Oregon Plan for Salmon and Watersheds: Sampling design and statistical analysis methods for the integrated biological and physical monitoring of Oregon streams

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Introduction

The Oregon Department of Fish and Wildlife (ODFW) has conducted surveys of coho salmon spawning on Oregon coastal streams for over 50 years (Jacobs et al. 2001). The initial surveys were done on purposefully selected streams. The sampling design was switched to a stratified random probability design in 1990 (Urquhart and Kincaid, 1999). The current concern with long-term viability of coastal coho populations sparked a review of that design, with an objective of achieving an integrated sampling approach for spawning salmon, juvenile salmon, and freshwater physical habitat. For each for these populations, there was an interest not only in current status in terms of fish numbers or habitat quality, but also in regional temporal trends. In addition, the Oregon Department of Environmental Quality (DEQ) wanted a much smaller sample from the same stream population to measure water quality. The design discussed in this report addresses all of these objectives.