Salmon and the subsurface

David Dralle, Gabe Rossi, Phil Georgakakos, Jesse Hahm, Daniella Rempe, Monica Blanchard, Mary Power, Bill Dietrich, and Stephanie Carlson, CALIFORNIA WATERBLOG

Our central hypothesis is that we will not recover salmon abundance without recovering a diversity of paths through the watershed and through the life cycle and, moreover, that the strategies that are missing or only weakly contributing today are ones that relied on the mainstem and other non-natal habitats for rearing / as stop over sites…

You’ve probably noticed that some streams flow year-round while others are seasonally dry, despite receiving similar amounts of rainfall. Through a recent NSF-funded effort (“Eel River Critical Zone Observatory”), we learned several things about how landscapes filter climate to produce such diverse flow behavior–and the implications for how salmon live their lives.

Our 25-year field study revealed that belts of California’s Eel River watershed underlain by different geologies have different Critical Zones (CZs) – Earth’s permeable surface layers from the top of the vegetation canopy down to fresh bedrock, where water can be stored and exchanged.