A Preliminary Classification and Mapping of Salmon Ecological Systems In the Nushagak and Kvichak Watersheds, Alaska By Christine Woll David Albert and Diane Whited A preliminary classification and mapping of salmon ecological systems in the Nushagak and Kvichak Watersheds, Alaska Contents Table of Tables ................................................................................................................................................... 3 Table of Figures ................................................................................................................................................. 5 Executive Summary ........................................................................................................................................... 9 Introduction ...................................................................................................................................................... 10 Objective 1: Mapping salmon habitat .......................................................................................................... 14 Freshwater Habitat and Salmon ................................................................................................................ 14 Sockeye salmon ........................................................................................................................................ 14 Chinook salmon ....................................................................................................................................... 16 Coho salmon ............................................................................................................................................ 18 Chum salmon ........................................................................................................................................... 19 Pink salmon .............................................................................................................................................. 20 Mapping and modelling freshwater habitat in the Nushagak and Kvichak watersheds .................... 20 Fine-scale analysis .................................................................................................................................... 20 Coarse-scale analysis ............................................................................................................................... 29 Objective 2: Mapping patterns of salmon relative abundance ................................................................. 40 Best available salmon distribution and abundance information ........................................................... 40 Sockeye salmon ........................................................................................................................................ 40 Chinook .................................................................................................................................................... 55 Coho salmon ............................................................................................................................................ 64 Chum salmon ........................................................................................................................................... 70 Pink salmon .............................................................................................................................................. 76 Estimating Habitat Suitability by Species and Life Stage ....................................................................... 80 Sockeye salmon ........................................................................................................................................ 81 Chinook salmon ....................................................................................................................................... 83 Coho salmon ............................................................................................................................................ 86 Chum salmon ........................................................................................................................................... 88 Pink salmon .............................................................................................................................................. 89 Conclusions ....................................................................................................................................................... 91 Mapping salmon habitat.............................................................................................................................. 91 Fine-scale analysis .................................................................................................................................... 91 Coarse scale analysis ................................................................................................................................ 94 Mapping patterns of salmon relative abundance .................................................................................... 95 Final conclusions.......................................................................................................................................... 96 References ......................................................................................................................................................... 98 2 Table of Tables Table 1. Buffer distances and maximum elevation thresholds to define floodplain spatial extent..... 23 Table 2. Estimated total sockeye salmon run size (in thousands) for the Nushagak river watershed. This excludes the Wood River, Igushik, and Snake River systems. .......................................................... 42 Table 3. Estimated total sockeye run size (in thousands) for the Kvichak watershed. This excludes the Alagnak and the Naknek river systems. ................................................................................................. 43 Table 4. Estimated total sockeye escapement (in thousands) for the Lake Clark watershed. ............. 44 Table 5. Estimated total sockeye escapement (in thousands) for the Tazimina watershed. ................ 45 Table 6. Estimated sockeye salmon smolt production (in thousands) by brood year for the Kvichak River (Crawford 2001)..................................................................................................................................... 54 Table 7. Estimated sockeye salmon smolt production (in thousands) by brood year for the Nuyakuk River (Woolington et al. 1991). ...................................................................................................................... 55 Table 8. Estimated total Chinook salmon run size for the Nushagak river watershed. This excludes the Wood River, Igushik, and Snake River systems. ................................................................................... 57 Table 9. Commercial Chinook salmon catch for the Naknek-Kvichak fishing district. This includes fish destined for the Naknek and Alagnak systems in addition to the Kvichak watershed. ................. 58 Table 10. Commercial coho salmon catch for the Naknek-Kvichak and Nushagak fishing districts. For the Naknek-Kvichak fishing district, this includes fish destined for the Naknek and Alagnak systems in addition to the Kvichak watershed. For the Nushagak district, this includes fish destined for the Wood River, Igushik, and Snake River systems in addition to the Nushagak river watershed. ............................................................................................................................................................................ 66 Table 11. Estimated total chum salmon run size for the Nushagak River. This excludes the Wood River, Igushik, and Snake River systems. ..................................................................................................... 72 Table 12. Commercial chum salmon catch for the Naknek-Kvichak fishing district. This includes fish destined for the Naknek and Alagnak systems in addition to the Kvichak watershed. ................. 73 Table 13. Commercial pink catch for the Nushagak and Naknek-Kvichak fishing district. The Nushagak district includes fish destined for the Wood River, Igushik, and Snake River systems in addition to the Nushagak river watershed and the Naknek-Kvichak fishing district includes fish destined for the Naknek and Alagnak systems in addition to the Kvichak watershed. The twenty- year average for pink salmon only includes even-number years. .............................................................. 78 Table 14. Habitat suitability assignments for sockeye salmon spawning habitat model. ..................... 81 Table 15. Habitat suitability assignments for sockeye salmon rearing habitat model. .......................... 82 A preliminary classification and mapping of salmon ecological systems in the Nushagak and Kvichak Watersheds, Alaska Table 16. Habitat suitability assignments for Chinook salmon spawning habitat model. ................... 84 Table 17. Habitat suitability assignments for Chinook salmon rearing habitat model. ........................ 85 Table 18. Habitat suitability assignments for coho salmon spawning habitat model. .......................... 87 Table 19. Habitat suitability assignments for coho salmon rearing habitat model. .............................. 88 Table 20. Habitat suitability assignments for chum salmon spawning habitat model. ........................