Thompson River Fisheries Investigations: A Compilation Through 2017 Prepared by: Ryan Kreiner and Marc Terrazas Montana Fish, Wildlife, and Parks Thompson Falls, MT 2018 Contents INTRODUCTION ....................................................................................................................................... 1 Landownership .......................................................................................................................................... 3 Roads ........................................................................................................................................................ 4 Fish Stocking Summary ............................................................................................................................. 7 Angler pressure ......................................................................................................................................... 8 MAINSTEM FISHERIES MONITORING ............................................................................................. 9 Methods ................................................................................................................................................... 10 Results ..................................................................................................................................................... 13 Rainbow Trout .................................................................................................................................... 13 Brown Trout ........................................................................................................................................ 18 Bull Trout . ........................................................................................................................................... 23 Westslope Cutthroat Trout .................................................................................................................. 24 Brook Trout ......................................................................................................................................... 26 Mountain Whitefish ............................................................................................................................. 26 Discussion ............................................................................................................................................... 27 MAINSTEM TEMPERATURE MONITORING .................................................................................. 34 Discussion ............................................................................................................................................... 36 TRIBUTARY MONITORING ................................................................................................................ 37 FISHTRAP CREEK ............................................................................................................................. 37 Drainage overview .............................................................................................................................. 37 Results ................................................................................................................................................. 37 Discussion ........................................................................................................................................... 38 Fishtrap Creek Temperature Monitoring . .............................................................................................. 39 Discussion ........................................................................................................................................... 39 Fishtrap Creek Genetics and Movement ................................................................................................. 40 Fishtrap Creek (mainstem) ................................................................................................................. 41 Fishtrap Lake ...................................................................................................................................... 42 West Fork Fishtrap Creek ................................................................................................................... 42 Beatrice Creek .................................................................................................................................... 42 Jungle Creek ....................................................................................................................................... 42 JUNGLE CREEK ..................................................................................................................................... 42 ii Routine monitoring ................................................................................................................................. 42 Results ..................................................................................................................................................... 42 Discussion ............................................................................................................................................... 43 WEST FORK THOMPSON RIVER ...................................................................................................... 44 Drainage overview .................................................................................................................................. 44 Long-term monitoring ............................................................................................................................. 44 Results ..................................................................................................................................................... 44 Discussion ............................................................................................................................................... 45 WFTR Temperature Monitoring ............................................................................................................. 46 Discussion ............................................................................................................................................... 46 Genetics Sampling .................................................................................................................................. 47 West Fork Thompson River ................................................................................................................. 47 Four Lakes Creek ................................................................................................................................ 47 BIG ROCK CREEK ................................................................................................................................. 47 Methods ................................................................................................................................................... 47 Results ..................................................................................................................................................... 48 Discussion ............................................................................................................................................... 50 Fisheries Monitoring . ............................................................................................................................. 50 Discussion ............................................................................................................................................... 51 Temperature Monitoring ......................................................................................................................... 53 Genetics Sampling .................................................................................................................................. 55 Little Rock Creek ................................................................................................................................. 55 McGinnis Creek .................................................................................................................................. 55 Alder Creek ......................................................................................................................................... 55 OUTMIGRATION STUDIES ................................................................................................................. 56 Introduction and Methods ....................................................................................................................... 56 2000-2002 ........................................................................................................................................... 56 2014-2017 ........................................................................................................................................... 56 Results ..................................................................................................................................................... 57 Weir Traps (Fishtrap Creek) ............................................................................................................... 57 Weir Traps (West Fork Thompson River) ........................................................................................... 58 Electrofishing and PIT tag arrays .....................................................................................................