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Title: Influence of river level on temperature and hydraulic gradients in chum and fall Chinook salmon spawning areas downstream of Bonneville Dam, Columbia River

Chum (Oncorhynchus keta) and fall Chinook (O. tshawytscha) salmon segregate spatially during spawning in the Ives Island side channel of the lower Columbia River downstream from Bonneville Dam. Previous research during one spawning season (2000) suggested that these species selected spawning habitats based on differences in hyporheic temperature and vertical hydraulic gradient (VHG) with the river. In this study, we confirmed the spatial segregation of spawning based on hyporheic characteristics over four years (2001–2004) and examined the effects of load-following operations (power generation to meet short-term electrical demand) at Bonneville Dam on hyporheic function and characteristics. We found that during the study period, hyporheic temperature and VHG in chum salmon spawning areas were highly variable during periods of load-following operation when river levels fluctuated. In contrast, hyporheic water temperature and VHG within chum spawning areas fluctuated less when river levels were not changing due to load-following operation. Variable temperature and VHG could affect chum and fall Chinook salmon spawning segregation and incubation success by altering the cues each species uses to select redd sites. Alterations in site selection would result in a breakdown in the spatial segregation of spawning between chum and fall Chinook salmon, which would expose earlier spawningmore » fall Chinook eggs to a greater risk of dislodgement from later spawning chum salmon. Additional research will be required to fully assess the effects of load-following operations on the hyporheic environment and spawning and incubation success of chum and fall Chinook salmon downstream from Bonneville Dam.« less
Authors:
; ; ; ; ;
Publication Date:
OSTI Identifier:
928268
Report Number(s):
PNNL-SA-53405
400480000; TRN: US200815%%588
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: North American Journal of Fisheries Management, 28(1):30-41; Journal Volume: 28; Journal Issue: 1
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
13 HYDRO ENERGY; COLUMBIA RIVER; HYDRAULICS; INCUBATION; SALMON; DAMS; HABITAT; AMBIENT TEMPERATURE; LEVELS; HYDROELECTRIC POWER PLANTS; BIOLOGICAL EFFECTS