Spatial consistency of chinook salmon redd distribution within and among years in the Cowlitz River, Washington

North American Journal of Fisheries Management
By: , and 

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Abstract

We investigated the spawning patterns of Chinook Salmon Oncorhynchus tshawytscha on the lower Cowlitz River, Washington, using a unique set of fine- and coarse-scale temporal and spatial data collected during biweekly aerial surveys conducted in 1991–2009 (500 m to 28 km resolution) and 2008–2009 (100–500 m resolution). Redd locations were mapped from a helicopter during 2008 and 2009 with a hand-held GPS synchronized with in-flight audio recordings. We examined spatial patterns of Chinook Salmon redd reoccupation among and within years in relation to segment-scale geomorphic features. Chinook Salmon spawned in the same sections each year with little variation among years. On a coarse scale, 5 years (1993, 1998, 2000, 2002, and 2009) were compared for reoccupation. Redd locations were highly correlated among years. Comparisons on a fine scale (500 m) between 2008 and 2009 also revealed a high degree of consistency among redd locations. On a finer temporal scale, we observed that Chinook Salmon spawned in the same sections during the first and last week. Redds were clustered in both 2008 and 2009. Regression analysis with a generalized linear model at the 500-m scale indicated that river kilometer and channel bifurcation were positively associated with redd density, whereas sinuosity was negatively associated with redd density. Collecting data on specific redd locations with a GPS during aerial surveys was logistically feasible and cost effective and greatly enhanced the spatial precision of Chinook Salmon spawning surveys.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Spatial consistency of chinook salmon redd distribution within and among years in the Cowlitz River, Washington
Series title North American Journal of Fisheries Management
DOI 10.1080/02755947.2013.778924
Volume 33
Issue 3
Year Published 2013
Language English
Publisher Taylor & Francis
Contributing office(s) Forest and Rangeland Ecosystem Science Center
Description 11 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title North American Journal of Fisheries Management
First page 508
Last page 518
Country United States