Floodplains and food webs: evaluating the benefits of tidal delta restoration for Chinook salmon and their prey

PRINCIPAL INVESTIGATOR: Anne Beaudreau (University of Washington)

CO-INVESTIGATORS: Emily Howe (The Nature Conservancy), Michael LeMoine (Skagit River System Cooperative), Jason Toft (University of Washington)

Chinook salmon are cultural and ecological keystone species, supporting customary and traditional use by Indigenous peoples, providing sustenance and livelihoods to diverse communities, and shaping food webs and ecosystems. Puget Sound Chinook salmon are listed as threatened under the ESA and their recovery relies on restoration of large river deltas. For the Stillaguamish River delta, where land is in high demand for multiple uses, understanding how much habitat is needed to support salmon recovery is essential for meeting social-ecological goals. This understanding requires in-depth, place-based research to link restoration actions to ecological outcomes for species and food webs, a component that is often overlooked in the design and evaluation of restoration projects.

This study will contribute to collaborative work to understand restoration effects on Chinook salmon recovery in the Salish Sea by assessing the diets and body condition of juvenile Chinook salmon among sites with differing restoration status; evaluating diversity, density, and quality of invertebrate prey communities for salmon at these same sites; and generating salmon growth potential estimates using the diet and prey data to evaluate bottom-up effects of restoration on outmigrating Chinook salmon. This proposal significantly leverages and extends ongoing work led by NGOs and Tribes to assess effects of restoration in the Stillaguamish estuary.