adfluvial bull trout v 4.doc 12/21/99 Modeling Seasonal Trophic Interactions of Adfluvial Bull Trout in Lake Billy Chinook, Oregon Pelton Round Butte Hydroelectric Project FERC No. 2030 Prepared for Portland General Electric Company by David A. Beauchamp 1 and Jason J. Van Tassell Utah Cooperative Fisheries and Wildlife Research Unit 2 , Department of Fisheries and Wildlife, and Ecology Center Utah State University Logan, Utah 84322-5255 December 1999 1 Present address: Washington Cooperative Fisheries and Wildlife Research Unit, University of Washington, School of Fisheries, Box 355020, Seattle, WA 98020, (206) 221-5791, daveb@fish.washington.edu 2 The Unit is jointly sponsored by the Biological Resources Division of U.S. Geological Survey, Utah State University, Utah Division of Wildlife Resources, and the Wildlife Management Institute.