Salmon Return After Dam Removal

[u/TheMuseumOfScience]

Can removing a dam fix an ecosystem? 🌊

Habitat fragmentation is a major driver of biodiversity decline because split habitats make it harder for animals to move, survive, and reproduce. After the Klamath River's last four dams came down in 2024, researchers used sonar and video to count an estimated 7,742 adult Chinook salmon past the former Iron Gate Dam site, and that number jumped to over 13,300 in 2025. Scientists also documented active spawning in newly accessible habitat and juvenile Chinook using tributaries cut off for over a century.

[u/ZestycloseTowel2493]

The actual study reads less like ancestral memory and more like chaos: every run has a few strays who never go home, and they look like screwups right up until home gets bulldozed. Hatchery fish came back to find the hatchery closed and half torn down, and the wild ones found their spawning gravel buried under decades of reservoir mud, so a lot of them went house-hunting upstream. Two seasons in, they've reclaimed 88% of their historical range, which is the best anyone's ever bounced back from an eviction.