Modeling Effects of Habitat Change and Restoration Alternatives on Salmon in the Chehalis River Basin Using a Salmonid Life-Cycle Model

A key element of the Aquatic Species Restoration Plan (ASRP) for the Chehalis Basin is habitat restoration for anadromous salmonids of economic and cultural significance, including spring and fall Chinook salmon (Oncorhynchus tshawytscha), coho salmon (O. kisutch), steelhead (O. mykiss), and chum salmon (O. keta). The chum model results will be released in 2020. To assist with development of the Chehalis basin ASRP, the National Oceanic and Atmospheric Administration (NOAA) Northwest Fisheries Science Center developed a suite of analyses and models to assess habitat changes from historical (pre-EuroAmerican settlement or natural potential) conditions to present. The results of those habitat assessments were then used in a salmonid Life-Cycle Model (LCM) with nine diagnostic scenarios to determine which types of habitat changes most limit rebuilding of salmon populations within the Chehalis Basin, and how those limitations vary by subbasin. This identification of habitat constraints is intended to help identify key restoration actions for salmon populations in the basin. In addition to modeling the diagnostic scenarios, three restoration scenarios developed by the Science and Review Team (SRT) and Steering Committee (including climate change and future development) were modeled to evaluate potential improvements in salmon and steelhead populations in the future. This modeling completes Phase 1 of the NOAA modeling process. Additional modeling will occur in Phase 2 of developing the ASRP. 2021 Contract no. WDFW #15-03970 Contract no. RCO #17-1477 NMFS (National Marine Fisheries Service) NWFSC (Northwest Fisheries Science Center) Submitted https://doi.org/10.25923/v003-kk27 Public Domain 1861