Mobile acoustic surveys of 24-h duration were undertaken at Steveston Bend between 1991 and 1993, close to the time of maximum adult Early Stuart sockeye salmon (Oncorhynchus nerka) abundance in the Fraser River estuary. During each survey, extreme variations in the abundance and directional orientation of fish targets appeared to be related to local flow direction and velocities. Acoustic Doppler Current Profiler (ADCP) measurements of water currents adjacent to the fish monitoring site showed that the water column stratified into two vertical layers under certain tidal conditions, with an upper outflowing layer over a lower inflowing layer. Under strong flood or ebb conditions, most of the water column was, respectively, inflowing or outflowing. Fish abundance in the water column appeared to be related primarily to tidal current variations. Maximum fish abundance and upstream orientation occurred during flood tidal periods with upstream current flows. We conclude that migrations of Early Stuart sockeye salmon are synchronized with the tidal cycle for energetically efficient net upstream displacement through the Fraser River estuary.
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.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.