The Yakama Nation and Nez Perce Tribe are federally recognized tribes with reserved treaty-rights to take fish at all usual and accustomed areas. The right to harvest fish includes the responsibility to protect, manage, and enhance treaty fishery resources. As anadromous fish mangers, we conduct and contribute to fish population status monitoring. This memorandum updates the Adaptive Management Implementation Plan (AMIP) trigger analysis through spawn year 2024 for natural-origin adult anadromous fish returning to the Upper Columbia, Middle Columbia, and Snake River basins. The analysis was last completed and presented to the Regional Implementation and Oversight Group (RIOG) on February 4th, 2020, by Josie Thompson and Ritchie Graves of National Marine Fisheries Service (NMFS). Their 2020 analysis found recent returns for Upper Columbia spring Chinook, Upper Columbia steelhead, and Snake River steelhead below AMIP abundance and trend thresholds in some years.
The updated analysis [see download below] evaluates adult returns through spawn year 2024 for Upper Columbia spring (sp) Chinook, Upper Columbia Steelhead, Middle Columbia Steelhead (Yakima River), Snake River fall Chinook, Snake River spring/summer (sp/su) Chinook, and Snake River steelhead stocks. The updated analysis uses the best available abundance series as agreed upon by local and regional fisheries managers and described below. The methods used to recalculate AMIP abundance and trend triggers follows the original approach outlined in Appendix 4 of the 2009 AMIP document(1) and in the 2018 Federal Columbia River AMIP indicator and trigger update document(2).
