August 21, 2025 — The Nez Perce Tribe and its collaborators will try to eke out a few more years’ survival for Tucannon River Chinook.
“But,” Jay Hesse says, “we also had to ask: What about all the other populations? So in 2021, we started modeling quasi-extinction for all the Snake River spring/summer Chinook and steelhead populations listed under the Endangered Species Act. The results are giving us a better picture of real conditions, and a stronger case for the urgency of action.”
Mr. Hesse is the director of Biological Services for the Nez Perce Department of Fisheries Resources Management.
Some years ago, federal scientists at National Oceanic and Atmospheric Administration Fisheries developed the “quasi-extinction threshold,” which the NOAA uses in planning.
For Snake River Chinook salmon and steelhead, the threshold is fewer than 50 adult fish in a population returning from the ocean for four consecutive years. Below that floor, the population’s continued existence can no longer be scientifically assumed or predicted. It is an emergency signal, flashing red and near black.
The Nez Perce Tribe is applying this science to management of populations below or near the extinction threshold, as well as to public education and long-term science.
Nez Perce Fisheries provided me two maps from its upcoming extinction threshold report for Snake River spring/summer Chinook, and steelhead, updated through 2024 fish returns. These maps show some of the findings, but much else in it will deserve attention.