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Reduced recruitment of Chinook salmon in a leveed bar-built estuary

Canadian Journal of Fisheries and Aquatic Sciences
By:  and 
https://doi.org/10.1139/cjfas-2020-0122

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Abstract

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.

Publication type Article
Publication Subtype Journal Article
Title Reduced recruitment of Chinook salmon in a leveed bar-built estuary
Series title Canadian Journal of Fisheries and Aquatic Sciences
DOI 10.1139/cjfas-2020-0122
Volume 78
Year Published 2021
Language English
Publisher Canadian Science Publishing
Contributing office(s) Coop Res Unit Seattle
Description 11 p.
First page 894
Last page 904
Country United States
State California
County Humboldt County
Other Geospatial Redwood Creek
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