Restored seasonally inundated habitat supports juvenile salmonid rearing and growth in two California Central Valley rivers.

This article evaluates the ecological effectiveness of four seasonally inundated habitat restoration projects designed to support juvenile Chinook Salmon (Oncorhynchus tshawytscha) rearing and growth in the Merced and Stanislaus rivers of California’s Central Valley. The study compared invertebrate prey abundance, juvenile salmon density, residence time, and growth between restored seasonal habitats and unrestored main-channel habitats across multiple years with varying flow conditions. Results showed that restored habitats generally supported comparable or higher invertebrate prey biomass and juvenile salmon densities, longer residence times, and greater total growth, with variation influenced by site characteristics, hydrology, and climate variability. The findings suggest that expanding seasonally inundated habitats can enhance juvenile salmon rearing capacity and life history diversity in regulated Mediterranean-climate rivers, although benefits depend on flow regimes and habitat design. These data can inform adaptive management and life cycle models aimed at salmonid population recovery in altered river systems.