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Classification and assessment of large U.S. reservoirs based on fish habitat impairment. Rebecca M. Krogman M.S. Candidate with Dr. Steve Miranda. Construction of large reservoirs.
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Classification and assessment of large U.S. reservoirs based on fish habitat impairment Rebecca M. Krogman M.S. Candidate with Dr. Steve Miranda
Construction of large reservoirs • “I think we all agree that the construction of reservoirs has been the greatest single contribution in this century to sport fishing and other forms of outdoor recreation.” • - Brigadier General H. G. Woodbury, Jr., US Army Corps of Engineers Background
Large reservoirs (>100 ha) National Inventory of Dams 2009
Comparison to natural lakes Background
Comparison to natural lakes Background
Fish habitat issues Delta behind Matilija Dam, California
Effects on fisheries • Habitat availability • Oxygen • Structure • Connectivity • Spawning success • Change water levels • Substrate composition (e.g., gravel beds) • Siltation • Littoral zone vegetation and structure Background
Effects on fisheries • Larval fish and fingerling survival • Food acquisition • Refuge from predation • Fish productivity • Nutrient dynamics • Availability of zooplankton and macroinvertebrates • Turbidity Background
Main points • Reservoirs are numerous and ubiquitous • Reservoirs are a product of public policy • Reservoirs are aging • Habitat degradation can affect recreational fisheries
Importance Background
Previous Survey Background: Previous Survey
Variables • Suspended sediments or inorganic turbidity • Sedimentation • Shoreline erosion • Excessive nutrients • Point-source pollution • Contaminants • Oxygen or temperature stratification • Mistimed water level fluctuations • Insufficient water storage • Excessive aquatic macrophytes • Lack of aquatic macrophytes • Lack or loss of woody debris • Disconnectivity with backwaters • Invasive plant species Background: Previous Survey
Data Analysis • Factor analysis • Interpretation of primary factors and spatial variation • Development of Index of Reservoir Habitat Impairment (IRHI) • 221 respondents 494 waterbodies Background: Previous Survey
Results Background: Previous Survey
Data Analysis Background: Previous Survey
New questions • What specific variables are important in each reservoir group? • How can we determine these reservoir groups? • How do these groups relate to the recreational fishery?
Thesis Project Objectives and Methods
Objectives • Classify large U.S. reservoirs based on fish habitat impairment factors. • Validate the classification system using empirical factors not included in Objective 1. • Explore the relationship between habitat impairment and the recreational fishery.
Data Collection • Potential sites identified • National Inventory of Dams, USACE • 4,331 sites identified Objective 1: Data Collection
Reservoirs ≥100 ha in surface area Objective 1: Data Collection
Data Collection • Potential sites identified • National Inventory of Dams, USACE • 4,331 sites identified • Survey of reservoir fishery biologists • Online • Best professional judgment • Topics • Habitat impairment • Fish community • Recreational fishery Objective 1: Data Collection
Survey Design Objective 1: Data Collection
Survey Design Objective 1: Data Collection
Survey Example Based on your experience with this reservoir, please indicate the extent to which the following concerns apply to this reservoir: Objective 1: Data Collection
Survey Example Please score the following fish community and fishery characteristics in this reservoir in relation to similar reservoirs nearby: Objective 1: Data Collection
Classify large U.S. reservoirs based on fish habitat impairment factors • Cluster analysis using impairment variables • Compare clusters to existing classification systems • Select the system that is both distinct and practical • reservoir classes Objective 1: Data Analysis
Validate the classification system using empirical factors • Existing data compiled by Green and Rodgers • Basin characteristics • Local watershed characteristics • In-reservoir characteristics Objective 2: Data Collection
Validate the classification system using empirical factors • Identify the empirical variables that explain class membership • Multiple discriminant function analysis • Multinomial logistic regression • Test significance of ability to discriminate • Apply to other reservoirs Objective 2: Data Analysis
Explore the relationship between habitat impairment and the recreational fishery • Use habitat impairment variables and fishery variables • Explore several techniques for associating fishery quality with habitat Objective 3: Data Collection
Potential Techniques • Multivariate ANOVA or similar nonparametric test • Canonical correlation analysis • Weights-of-evidence and weighted logistic regression • Artificial neural networks Objective 3: Data Analysis
Artificial Neural Network Predictor variables (Habitat impairment) Response variable (Fishery quality) Objective 3: Data Analysis
Weights-of-evidence Weighted Logistic Regression Objective 3: Data Analysis
Weights-of-evidence Weighted Logistic Regression • Repeat the process of Kapo and Burton (2006) • Adjust methods for reservoirs instead of streams Objective 3: Data Analysis
Conclusion • Objective 1: Classification system • Objective 2: Validation • Objective 3: Relate it to the fishery
Potential Applications • Make quantitative comparisons among reservoirs • Understand geospatialrelationships • Guide the decision-making process Fishing below J.T. Meyers Dam Conclusions
Questions or comments? Hoover Dam