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The Problem Bonneville Reservoir (BR) and its tributary streams are largely contained within the Columbia River Gorge National Scenic Area. Many recreational enthusiasts, including sport fisherman, heavily use the area. Fisheries in these areas provide fishing opportunities for white sturgeon, steelhead, spring chinook, fall chinook, and coho salmon, while recreational fisheries for native and non-native resident game fish
The fish community in the Columbia River has been affected by a combination of hydropower development, species introductions and invasions, over-harvest, and habitat degradation in tributaries from agricultural practices (e.g., timber harvest, irrigation withdrawals) and urbanization (Li et al. 1987; in Community and Evolutionary Ecology of North American Stream Fishes. University of Oklahoma Press, Norman, Oklahoma, Independent Science Group 2000; An alternative conceptual foundation for the Columbia River Basin Fish and Wildlife Program of the Northwest Power Planning Council). The nature of these disturbances suggests that the trophic-level dynamics of the Columbia River ecosystem and the role of tributaries in determining production of fishes in the mainstem have undergone significant changes. This study will document the aquatic community dynamics in a Columbia River reservoir and its major tributaries. Our primary focus will be to describe the abundance and distributions of fish, movements of fish, and fishery stability relative to environmental conditions in the river. In addition, we will compile existing information and collect new data to describe the terrestrial and aquatic habitats, land- and water-use activities, and the extent and abundance of aquatic invasive species that could potentially affect the fishery in this area. Objectives Our primary objectives for 2003 are to: 1) Compile existing data, collect new information, and derive parameters describing the aquatic and terrestrial habitats found within the study area and then incorporate this information into a GIS, 2) Compile existing information on the composition and abundance of macro-invertebrate populations and the abundance and distributions of fish within BR and its tributaries, 3) Collect information on thermal, nutrient, and discharge inputs into Bonneville Reservoir and work with the Geologic Division to collect information on the substrate composition and channel morphology of BR, and 4) Develop a website to display the information collected during 2001 and in subsequent years. Information from this project will provide a synthesis of aquatic community dynamics in a spatial framework. Linkage to the tributaries will help managers and researchers in the region better understand how this important reservoir functions and what inputs may regulate production and fish populations. Establishment of a resource assessment program, which is part of the long-term goal, will provide regional managers with appropriate data for measuring change in the reservoir. Methodology Bonneville Reservoir substrate characterization A cooperative effort between the USGS Coastal and Marine Geology Program and the USGS Biologic Resource Division, Columbia River Research Laboratory to map the surficial sediment distribution and sediment thickness within the Bonneville Reservoir was conducted during 2001. The goal of this study is to define benthic habitats and to assess sediment accumulation and its effects to the larger scale sediment budget of the Columbia River and adjacent coastal ocean. The study area encompassed roughly 70 km of the Columbia River from the Bonneville Dam to The Dalles. The USGS Cruise E1-01-CR was conducted within the Bonneville Reservoir, August 3 - 21, 2001.
The geophysical data were acquired using a Benthos (Datasonics) SIS-1000 system (comprised of a sidescan-sonar (~100 kHz) and sub-bottom profiler (2 - 7 kHz swept FM (CHIRP), and an Edgetech DF-1000 100/500 kHz dual-frequency sidescan-sonar system. The SIS-1000 was utilized to acquire sub-bottom data only; the sidescan-sonar portion of the system was not operational. These data were logged digitally, processed and mosaic in the field generating a base from which the sample locations were chosen. Grab sample, video, and still photographs were acquired using the SEABOSS system and used to ground-truth the sidescan-sonar data. Aquatic macrophyte bed mapping, Bonneville Reservoir, 2001-2002 Initial efforts to document the extent of Eurasian watermilfoil (Myriophyllum spicatum) in Bonneville Reservoir were initiated by the USGS Columbia River Research Laboratory during 2001 and continued during 2002. During 2001 and 2002, the USGS surveyed Bonneville Reservoir for aquatic macrophytes, including Eurasian watermilfoil. Aquatic macrophyte beds were sampled using a modified-rake sampler to collect specimens at each macrophyte bed. Species were identified to family. Percent composition of each species was estimated. Using a boat, the USGS collected samples and surveyed the Oregon and Washington shoreline from Bonneville Dam's forebay boat restricted zone (BRZ) at river kilometer (rkm) 235.1 to The Dalles Dam tailrace BRZ at rkm 307.8. Locations and boundaries of macrophyte beds were recorded using a global positioning system, and downloaded to Arcview
Highlights and Key Findings Existing information has been compiled for all major tributaries to the reservoir. Side-scan sonar and sub-bottom profiling data has been collected and is being processed by the Geologic Discipline. Preliminary results indicate that less fine sediment than expected is present in the reservoir but is greater than for other reservoirs where similar data have been collected. Surveys of shallow water habitat indicate that almost all of these habitat types are either occupied by the invasive aquatic plant, Eurasian watermilfoil or consist of rip-rap for railroad grades. Consequently, little pristine shoreline areas exist. Where Are We Headed In 2003 During 2003 data collection efforts will continue for this project. Objectives to be addressed include:
Project Contact Tim Counihan Email: tim_counihan@usgs.gov Publications |
