Salmon After the Dams: Measuring Recolonization and Reproduction

Chinook salmon entered and spawned in the reopened Klamath River soon after four dams were removed. What do these early observations establish about population recovery?

We examine Goodman and colleagues' 2026 Klamath paper alongside Pess and colleagues' 2024 Elwha study. Imaging sonar, species probabilities and ground surveys explain how researchers measured adult passage and spawning. Brood years, hatchery origin and returning offspring explain what is still needed to establish sustained reproduction.

A close reading of the methods, findings and limits of two dam-removal studies, following the evidence from newly accessible habitat to the next generation of salmon.

Papers:

Goodman et al. (2026), Scientific Reports: https://doi.org/10.1038/s41598-026-65437-0

Pess et al. (2024), Frontiers in Ecology and Evolution: https://doi.org/10.3389/fevo.2024.1241028

Chapters:

00:00 Salmon entering the reopened river

03:18 What the sonar could measure

07:11 What the spawning surveys established

09:33 Following offspring back from the ocean

13:31 What the Elwha records revealed

17:20 Measuring the years between spawning and return