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Fish habitat degradation in U.S. reservoirs

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  1. Fish habitat degradation in U.S. reservoirs Presented by Rebecca M. Krogman Department of Wildlife, Fisheries and Aquaculture Mississippi State University

  2. Acknowledgments • L. E. (Steve) MirandaMississippi Cooperative Fish and Wildlife Research Unit • W. Reed GreenUSGS Arkansas Water Science Center • Kirk RodgersPh.D. Student, University of Arkansas – Little Rock • Many, many state fisheries biologists! • Jeff BoxruckerRFHP Science & Data Committee Chair, Oklahoma Department of Wildlife Conservation (recently retired) • And everyone else at the Reservoir Fisheries Habitat Partnership! • Funding provided by U.S. Fish and Wildlife Service

  3. Introduction

  4. Construction of large reservoirs

  5. 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

  6. Large reservoirs (>250 acres) National Inventory of Dams 2009

  7. Comparison to natural lakes • Top in purple: Lake Itasca watershed • Bottom corner: Pool 2 of the Mississippi River Credit: Minnesota Pollution Control Agency

  8. Comparison to natural lakes

  9. Fish habitat issues Delta behind Matilija Dam, California

  10. 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

  11. Effects on fisheries • Larval fish and fingerling survival • Food acquisition • Refuge from predation • Fish productivity • Nutrient dynamics • Availability of zooplankton and macroinvertebrates • Turbidity

  12. Main points • Reservoirs are numerous and ubiquitous • Reservoirs are a product of public policy • Reservoirs are aging • Habitat degradation can affect recreational fisheries

  13. Importance

  14. Reservoir Habitat Survey #1 Objective: To document the extent of habitat degradation in reservoirs in the U.S.

  15. Methods

  16. 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

  17. Data Analysis • Factor analysis • Interpretation of primary factors and spatial variation • Development of Index of Reservoir Habitat Impairment (IRHI) • 221 respondents  494 waterbodies

  18. Results

  19. Data Analysis

  20. Data Analysis

  21. Spatial Variations

  22. Spatial Variations

  23. Spatial Variations

  24. Spatial Variations

  25. Spatial Variations

  26. New questions • What specific variables are important in each reservoir group? • How can we determine these reservoir groups? • How much of what we see is natural variation?

  27. Reservoir Habitat Survey #2

  28. Reservoirs as part of the landscape “In every respect, the valley rules the stream.” - H. B. N. Hynes, 1975 reservoir

  29. Objective 1 WWF Aquatic Ecoregions • Cluster analysis • Compare clusters to existing classification systems •  reservoir classes Develop a classification system for large U.S. reservoirs using impairment factors

  30. Objective 2 • Discriminant analysis • Empirical data • Basin characteristics • Local watershed characteristics • In-reservoir characteristics Validate the classification system using empirical factors

  31. Objective 3 • Ordination techniques to identify reservoirs with a high quality recreational fishery and good habitat • Predictive model development based on high-quality fishing reservoirs Develop a predictive model that assesses fish habitat impairment for each reservoir class

  32. Siltation Excessive suspended sediments or inorganic turbidity Sedimentation Shoreline erosion

  33. Potential Applications • Make quantitative comparisons among reservoirs • Understand geospatial relationships • Guide the decision-making process Fishing below J.T. Meyers Dam

  34. Questions or comments? To learn more about Survey #1 Miranda et al. 2010. Fish habitat degradation in U.S. reservoirs. Fisheries 35(4):175-184. Miranda and Hunt. 2010. An index of reservoir habitat impairment. Environmental Monitoring and Assessment. Published online. In press Hoover Dam.