Survival of Juvenile Salmonids Passing through Bypass Systems, Turbines, and Spillways with and without Flow Deflectors at Snake River Dams

Abstract

Using yearling chinook salmon Oncorhynchus tshawytscha and steelhead O. mykiss tagged with passive integrated transponders (PITs), we estimated passage survival through bypass systems, turbines, and spill bays with and without flow deflectors at Snake River dams relative to survival of fish released into the tailrace below the dam. Actively migrating fish were collected and marked with PIT tags at Snake River dam smolt collection facilities. Groups of tagged fish were then released through hoses into different passage routes; releases were coincident with a tailrace release approximately 1–2 km below the dam. Relative survival was estimated by the use of tag–recapture models for paired releases from detections of individual PIT‐tagged fish at juvenile collection or detection facilities at downstream dams. Detection sites included Little Goose, Lower Monumental, McNary, John Day, and Bonneville dams, depending on the release location and year. Standard errors of relative survival probability estimates were generally less than 3.0% through all potential passage routes. The estimated relative survival was highest through spill bays without flow deflectors (98.4–100%), followed by spill bays with flow deflectors (92.7–100%), bypass systems (95.3–99.4%), and turbines (86.5–93.4%). These estimates of relative survival, which include both the direct and indirect effects of passage, are generally higher than past estimates but similar to other recent estimates determined with modern techniques under present dam configurations and operating conditions.

Survival Rates of Juvenile Salmonids Passing Through the Bonneville Dam and Spillway in 2008

“…Johnson and Dawley (1974) reported that FC passing through BON spill bays without flow deflectors had a higher survival rate (95.8%) than FC passing through bays with flow deflectors (86.8%) and all flow deflectors at that time were located at middle bays where shallow flow deflectors are located today. Muir et al (2001) reported that spillway deflectors did not significantly affect survival rates of PIT-tagged YC and STH passing through spill bays at Little Goose and Lower Monumental dams with the sample sizes used, although point estimates were higher for fish passing through spill bays without flow deflectors than they were for fish passing through bays with deflectors.…”

Surgically Implanted JSATS Micro-Acoustic Transmitters Effects on Juvenile Chinook Salmon and Steelhead Tag Expulsion and Survival, 2010

“…In the Columbia River, scientists have identified acoustic telemetry as being an essential technology for observing the behavior and estimating the survival of juvenile salmonids passing through the side channels and the main stem FCRPS (Faber et al 2001;McComas et al 2005;Ploskey et al 2007;Ploskey et al 2008;Clemens et al 2009). Hydroelectric dams provide various routes of passage where mortality becomes pathway-specific depending on the physical properties of the technical installation (Coutant and Whitney 2000;Muir et al 2001;Skalski et al 2002;Weiland et al 2009). In addition, impoundments and passage facilities may delay the outmigration of juvenile salmonids, increasing their exposure to disease and predation.…”

Performance of an acoustic telemetry system in a large fishway

“…Many studies that involve detecting fish in confined spaces use passive integrated transponder (PIT tag) technology to detect fish at fixed points within juvenile bypass systems [15][16][17][18] or in fishways [19][20][21][22][23]. Studies have been conducted using a PIT tag with another telemetric technology, such as radio telemetry [13], by dual-tagging fish [15,16,19] or only using a PIT tag [17,18,[20][21][22][23][24].…”

“…Studies have been conducted using a PIT tag with another telemetric technology, such as radio telemetry [13], by dual-tagging fish [15,16,19] or only using a PIT tag [17,18,[20][21][22][23][24]. Although it has an advantage in terms of longevity of the tag relative to other technologies, PIT tags have short detection ranges that typically are less than 1 m in the tags' long axis, perpendicular to the antenna [24].…”