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Document Type: Chapter or Section
Center: NWFSC
Document ID: 1038
Type of Book: Technical
Section or Chapter Title: Hierarchical physical controls on salmonid spawning location and timing
Book Title: Salmonid spawning habitat in rivers: physical controls, biological responses, and approaches to remediation
Author: T. J. Beechie, Hamish Moir, G. R. Pess
Editor: David A. Sear, P. DeVries (Eds.)
Publication Year: 2008
Publisher: AFS Symposium 65. American Fisheries Society. Bethesda, Maryland
Pages: 83-102
Keywords: spawning location, spawning timing, geomorphology

Salmonids select spawning locations on the basis of site characteristics such as depth, velocity, substrate size, and cover availability, as well as flow regime and temperature regime. However, some aspects of spawning behavior are regulated by factors operating at much larger spatial scales, reflecting regional or continental gradients in key environmental attributes. In this paper we illustrate that physical and climatic controls on salmonid spawning locations and timing are hierarchically arranged, and that these controls create multi-scale patterns in spawning location and timing. For example, at the continental scale spawning timing is correlated with latitude, reflecting associated gradients in hydrologic and temperature regimes. At the regional scale, patterns in spawning timing reflect flow and temperature regimes that are controlled by regional topography and climate, whereas salmonid spawning locations are limited by both natural and anthropogenic barriers. Spatial patterns at the basin scale are strongly related to the distribution of geomorphic process regimes and channel morphologies, whereas reach-level patterns are influenced by local hydraulic characteristics, wood abundance, and upwelling and downwelling locations. Understanding of ultimate (large-scale) controls on salmonid spawning is useful in identifying populations or management units, whereas understanding of proximate (small-scale) controls is useful in prescribing management actions.

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