POTLATCH RIVER STEELHEAD MONITORING AND EVALUATION PROJECT 2017 AND 2018 BIENNIAL REPORT Prepared by: Brian A. Knoth, Fisheries Biologist Brett J. Bowersox, Fishery Staff Biologist Jason T. Fortier, Fisheries Technician 2 IDFG Report Number 20-15 March 2021 POTLATCH RIVER STEELHEAD MONITORING AND EVALUATION PROJECT 2017 AND 2018 BIENNIAL REPORT By: Brian A. Knoth Brett J. Bowersox Jason T. Fortier Idaho Department of Fish and Game 600 South Walnut Street P.O. Box 25 Boise, ID 83707 IDFG Report Number 20-15 March 2021 TABLE OF CONTENTS Page ABBREVIATIONS AND ACRONYMS .........................................................................................1 FOREWORD ..............................................................................................................................2 PROJECT OVERVIEW ...............................................................................................................2 PROJECT DESIGN AND OBJECTIVES ..................................................................................... 3 PROJECT TIMELINE ..................................................................................................................4 REPORT STRUCTURE ..............................................................................................................4 LITERATURE CITED ...............................................................................................................5 FIGURES ....................................................................................................................................7 CHAPTER 1: ABUNDANCE AND PRODUCTIVITY OF STEELHEAD WITHIN POTLATCH RIVER, IDAHO INDEX WATERSHEDS .......................................................... 10 ABSTRACT ...............................................................................................................................10 INTRODUCTION ......................................................................................................................11 METHODS ................................................................................................................................11 Adult Steelhead Escapement and Diversity ............................................................................ 11 Juvenile Steelhead Emigration, Diversity, and Survival .......................................................... 11 Productivity Estimates ............................................................................................................ 12 RESULTS ................................................................................................................................. 12 Adult Steelhead Escapement and Diversity ............................................................................ 12 Big Bear Creek ....................................................................................................................12 East Fork Potlatch River ...................................................................................................... 13 Juvenile Steelhead Emigration, Diversity, and Survival .......................................................... 14 Big Bear Creek ....................................................................................................................14 East Fork Potlatch River ...................................................................................................... 14 Population Productivity ........................................................................................................... 15 Big Bear Creek ....................................................................................................................15 East Fork Potlatch River ...................................................................................................... 15 DISCUSSION............................................................................................................................15 RECOMMENDATIONS ............................................................................................................. 18 LITERATURE CITED ................................................................................................................ 19 TABLES ....................................................................................................................................22 FIGURES ..................................................................................................................................24 CHAPTER 2: JUVENILE STEELHEAD PRODUCTIVITY AND HABITAT CONDITION RESPONSE TO HABITAT RESTORATION IN SELECT TRIBUTARIES WITHIN THE POTLATCH RIVER, IDAHO ................................................................................................ 38 ABSTRACT ...............................................................................................................................38 INTRODUCTION ......................................................................................................................39 METHODS ................................................................................................................................39 Habitat Surveys ......................................................................................................................39 Juvenile Steelhead Density, Parr-to-Smolt Survival, and Growth ........................................... 40 RESULTS ................................................................................................................................. 42 Habitat Surveys ......................................................................................................................42 i Lower Potlatch River Watershed ......................................................................................... 42 Upper Potlatch River Watershed ......................................................................................... 42 Juvenile Steelhead Density, Parr-to-Smolt Survival, and Growth ........................................... 42 Lower Potlatch River Watershed ......................................................................................... 42 Juvenile Steelhead Density ........................................................................................... 42 Parr to Smolt Survival .................................................................................................... 42 Growth Rates ................................................................................................................ 43 Upper Potlatch River Watershed ......................................................................................... 43 Juvenile Density ............................................................................................................ 43 Parr to Smolt Survival .................................................................................................... 43 DISCUSSION............................................................................................................................44 RECOMMENDATIONS ............................................................................................................. 47 ACKNOWLEDGEMENTS ......................................................................................................... 48 LITERATURE CITED ................................................................................................................ 49 TABLES ....................................................................................................................................52 FIGURES ..................................................................................................................................55 ii LIST OF TABLES Page Table 1. Age frequencies of wild adult steelhead captured at Potlatch River weirs and known destination wild adult steelhead sampled at Lower Granite Dam, 2008-2018. Partially aged fish were indicated by an X and repeat spawners were signified by R. ............................................................................................ 23 Table 2. Large wood density, pool density, and canopy cover within the East Fork Potlatch River treatment reach (EFPR treatment), the East Fork Potlatch River control reach (EFPR control), and West Fork Potlatch River control tributary (WFPR control) in the upper Potlatch River watershed during 2003–2018. Dashes indicate no data collected. ................................................. 53 Table 3. Number of juvenile steelhead (>80 cm) PIT tagged in Potlatch River tributaries for parr-to-smolt survival analyses from 2008-2018. Values in parenthesis indicate number of tagged fish subsequently detected in the hydrosystem. ..................................................................................................... 53 Table 4. Summer-fall growth of juvenile steelhead (≥80 mm) in select tributaries in the lower watershed of the Potlatch River, Idaho from 2014-2018. West Fork Little Bear Creek (WFLBC) and Little Bear Creek (LBC) are treatment tributaries and Pine Creek (PNC) is the control tributary. ................................... 54 iii LIST OF FIGURES Page Figure 1. Key features and monitoring infrastructure in the Potlatch River basin in northern Idaho. ....................................................................................................8 Figure 2. Timeline of project monitoring and restoration implementation in Big Bear Creek watershed in the Potlatch River Basin. ...................................................... 9 Figure