Estuaries are commonly touted as nurseries for salmonids, providing numerous advantages for smolts prior to ocean entry. In bar-built estuaries, sandbars form at the mouth of rivers during periods of low stream flow, closing access to the ocean and preventing outmigration. We evaluated how summer residency in a leveed bar-built estuary affects the growth, survival, and recruitment of a Chinook salmon (Oncorhynchus tshawytscha) population. We performed a mark-recapture study on outmigrants to determine juvenile estuary abundance, growth, and survival. We used returning adult scales and otoliths to determine the relative proportion of summer estuary residents in spawning adults. Juveniles in the estuary grew less after mouth closure, and ultimately summer estuary residents had lower smolt-to-adult survival and contributed disproportionately less to the spawning population than juveniles that reared in the ocean their first summer. Mouth closure may lower food availability and deteriorate estuary conditions by reducing marine prey influx and estuary circulation. This research demonstrates the complexity of estuary dynamics and function as salmonid nurseries, particularly when considering the extensive modification of estuaries.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.