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The Problem The U.S. Army Corps of Engineers (COE) is committed to increase the survival of juvenile salmon passing its projects on the Columbia River, and under requirements of the National Marine Fisheries Service (NMFS) Biological Opinion for operation of the Federal Columbia River power system (BiOp), they constructed a physical model of John Day Dam in 1995 for use in developing spill patterns for the project. In 1997-1998 new patterns at the project were adopted and the installation of dissolved gas dissipating deflectors was completed. Flow deflectors were installed to allow greater spill levels before reaching dangerous total dissolved gas concentrations. With the new spill patterns the COE sought to "reduce tailrace eddies, limit impacts to the juvenile bypass system outfall, limit retention time in the stilling basin and help to control dissolved gas" (AFEP research summary, SPE-P-00-7). By doing so the COE would decrease delay of juvenile salmon in the forebay and tailrace so that movement of downstream migrants would be less impeded and their exposure to predation would be reduced. In 1998 radio-telemetry and hydroacoustic evaluations of the spill patterns found low forebay retention and egress in the tailrace was swift. However under test spill treatments in 1999 and 2000 (12 h vs. 24 h, 30% vs. 60% spill) survival for spring and summer migrants was significantly less in the 24 h vs. 12 h spill, and forebay retention time was less during the 24 h spill regime. Also for the 30% vs. 60% treatments the evaluations found that greater discharge from spill lessened forebay residence time but it increased tailrace residence time for bypass-released fish (Beeman et al., 2000; Duran et al, 2000). With these findings it was now plausible that recommendations to hasten juvenile salmon from the forebay may inadvertently increase mortality of the same juvenile salmon in the tailrace. This could happen by creating hydraulic conditions that are more suitable for predators such as Northern Pikeminnow or Smallmouth Bass. Possible mechanisms for increased predation would be that spill patterns create hydraulic conditions which physically injure juvenile salmon or that the delay in their egress itself increases the chance for a predation event. Poe, Anglea, and Giorgi (2001) observed in their synthesis of previous studies of the tailrace environment of John Day Dam that "Spill patterns and operational conditions which cause smolts to have longer tailrace residence times will also concentrate smolts which may attract predators." And that "Route specific survival studies and predator monitoring studies are needed to better understand these risks." Our study will provide a baseline for research that seeks to answer questions that address the movement and behavior of fish in highly dynamic environments. Such research can be applied to any environment where similar conditions exist; an example might include the tailrace of The Dalles Dam, where juvenile salmon delay has been observed and where their subsequent delay may increase their mortality. Study findings will also offer insight into the performance of physical and computational models by validating such models with field results. One assumption, in relation to physical model results, is that dye movement patterns in the model are representative of fish movement patterns in the field. While most experts agree that the assumption is reasonable, these movement patterns have not been verified in the field at John Day Dam spillway. This project is funded through MIPR #W66QKZ20505686 (COE). Objectives The goal of this study is to determine egress routes and egress timing of juvenile salmon with respect to passive particle movement in the tailrace of John Day Dam using ultra-sonic fish tracking technology. We will evaluate the routes of juvenile salmon passage by their entrance into the stilling basin, quantify their egress time, and evaluate their movement with respect to tagged neutrally buoyant drogues. Data acquired during the tests will provide insight into fish behavior with respect to the movement of neutrally buoyant drogues under various spill conditions. The objectives are to evaluate egress routes and egress timing of juvenile spring chinook salmon with respect to paired releases of neutrally buoyant drogues into the stilling basin of John Day Dam during various spill scenarios. Methodology We propose to use a three-dimensional (3-D) fish tracking system to examine the movements of acoustically tagged fish in the tailrace of John Day Dam. Highlights and Key Findings In the spring of 2002 Battelle and USGS conducted a feasibility study that will determine the efficacy of using acoustic telemetry systems in the tailraces of hydroelectric dams to study movements of juvenile salmonids for the Portland District of the USACE. Although the data is still being analyzed for that season, a few key lessons were learned from the deployment and monitoring of the acoustic telemetry system at Lower Granite Dam. We determined that the detection range of hydrophones was significantly reduced during spill, and pending further analysis, it is likely that a negative correlation exists between spill volume and detection range (as spill increases, detection range decreases). The range of detection also varied with flow direction as it related to hydrophone position. The detection range for tags upstream of a hydrophone was 3-4 times greater than the detection range of tags downstream of a hydrophone (i.e. 200 ft detection upstream, and 50 ft detection downstream of hydrophone). Equipment durability was another issue with deployment into the tailrace. The majority of hydrophones and cable that were directly exposed to the spill patterns for Lower Granite in the spring season survived in working order. However, by the end of the season 1/3 of the hydrophones were not operating due to physical damage or a cable break. The majority of the damage occurred in the last month of operation, with only one (out of 16) hydrophone damaged in the first two weeks. Therefore a study that was designed to take place in the first month of a spill test would have less of a chance of losing data due to damaged equipment. Our proposed research for 2003 incorporates the lessons learned from the feasibility tests at Lower Granite, such as the reduced ranges for detection of hydrophones and equipment viability throughout the season, and takes advantage of these findings. Where Are We Headed In 2003 We will track the path of juvenile salmon and drogues during 30% and 60% spill conditions. We plan to release 100 ultra-sonically tagged juvenile salmon, 100 tagged neutrally buoyant drogues, and tagged GPS drogues into the spillway to complete this objective. Each release of a juvenile salmon into the spillway will be accompanied by the release of a neutrally buoyant drogue. Release sites will be selected for three locations (North, South and middle Spill) where the flow from spill passes through the entire hydrophone array. Fish and drogues will be released into the flow at these sites. We will analyze the duration and location of fish passage with respect to location of release and spill scenario. Several GPS drogue releases will be conducted at the same time, and at similar release points. GPS drogue releases will provide an independent source of flow tracking data, and an independent reference for tag detection ability of the acoustic fish tracking system. Project Contact Dennis Rondorf Email: dennis_rondorf@usgs.gov Publications |
