Redd Site Selection and Spawning Habitat Use by Fall Chinook Salmon: The Importance of Geomorphic Features in Large Rivers

Abstract

/ Knowledge of the three-dimensional connectivity between rivers and groundwater within the hyporheic zone can be used to improve the definition of fall chinook salmon (Oncorhynchus tshawytscha) spawning habitat. Information exists on the microhabitat characteristics that define suitable salmon spawning habitat. However, traditional spawning habitat models that use these characteristics to predict available spawning habitat are restricted because they can not account for the heterogeneous nature of rivers. We present a conceptual spawning habitat model for fall chinook salmon that describes how geomorphic features of river channels create hydraulic processes, including hyporheic flows, that influence where salmon spawn in unconstrained reaches of large mainstem alluvial rivers. Two case studies based on empirical data from fall chinook salmon spawning areas in the Hanford Reach of the Columbia River are presented to illustrate important aspects of our conceptual model. We suggest that traditional habitat models and our conceptual model be combined to predict the limits of suitable fall chinook salmon spawning habitat. This approach can incorporate quantitative measures of river channel morphology, including general descriptors of geomorphic features at different spatial scales, in order to understand the processes influencing redd site selection and spawning habitat use. This information is needed in order to protect existing salmon spawning habitat in large rivers, as well as to recover habitat already lost.KEY WORDS: Hyporheic zone; Geomorphology; Spawning habitat; Large rivers; Fall chinook salmon; Habitat management

Longitudinal hydraulic analysis of river‐aquifer exchanges

“…Fishes depend on groundwater seepage to create habitat for multiple life stages, maintain the carrying capacity of a river, provide refugia, and moderate water quality [Power et al, 1999]. Anadromous salmon, in particular, prefer locations of groundwater seepage for spawning [Geist and Dauble, 1998]. The upper Methow River provides critical spawning habitat for upper Columbia River spring chinook salmon (Oncorhynchus tswawytscha) [Beer and Anderson, 2001], a stock listed as threatened under the federal Endangered Species Act [U.S. Department of Commerce, 1999].…”

“…In alluvial valleys where the river does not fully penetrate the underlying aquifer and the primary groundwater flow component is longitudinal (down valley) with only a small lateral (across valley) component, a hydraulic analysis must be oriented longitudinally to represent the down-valley hydraulic gradient and flow paths [e.g., Harvey and Bencala, 1996;Woessner, 2000]. Likewise, flow between an aquifer and a river may have a vertical component [Lang and Rhodehamel, 1962;Toth, 1962;Geist and Dauble, 1998], which is not accommodated by customary applications of the Boussinesq equation.…”

Summary of Temperature Data Collected to Improve Emergence Timing Estimates for Chum and Fall Chinook Salmon in the Lower Columbia River, 1998-2004 Progress Report.

“…Fish and Wildlife Service [USFWS] and ODFW, unpublished data). This clustering suggests that these species may select specific, and different, spawning habitat features within the study area (Geist and Dauble 1998). Understanding the spatial distribution of subsurface temperature variation is critical to accurate estimation of emergence timing and establishment of meaningful minimum flows for the protection of spawning habitat in this area.…”

Spawning site selection and the influence of incubation environment on larval success in interior Fraser coho.

“…Traditionally, studies of spawning habitat selection have focused on stream depth, velocity and a physical property of the channel, such as substrate particle size (Milhous, 1979;Stalnaker, 1979;Bovee, 1982;Orth and Maughan, 1982;Milhous, 1999). Although, recently it has become evident that traditional habitat features may not provide the most effective means of assessing spawning habitat suitability (Mathur et al, 1985;Mull and Wilzback, 2007;Geist and Dauble, 1998;McHugh and Budy, 2004). Rather, the complexity of spawning site selection may encompass a wider range of habitat features.…”

“…In regions where winter temperatures drop below freezing, salmonids generally select spawning sites associated with groundwater upwelling (Leman, 1993;Geist and Dauble, 1998;Baxter and McPhail, 1999). Although the term "groundwater"…”