Diel activity patterns of juvenile late fall-run Chinook salmon with implications for operation of a gated water diversion in the Sacramento–San Joaquin River Delta

River Research and Applications
By: , and 

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Abstract

In the Sacramento-San Joaquin River Delta, California, tidal forces that reverse river flows increase the proportion of water and juvenile late fall-run Chinook salmon diverted into a network of channels that were constructed to support agriculture and human consumption. This area is known as the interior delta, and it has been associated with poor fish survival. Under the rationale that the fish will be diverted in proportion to the amount of water that is diverted, the Delta Cross Channel (DCC) has been prescriptively closed during the winter out-migration to reduce fish entrainment and mortality into the interior delta. The fish are thought to migrate mostly at night, and so daytime operation of the DCC may allow for water diversion that minimizes fish entrainment and mortality. To assess this, the DCC gate was experimentally opened and closed while we released 2983 of the fish with acoustic transmitters upstream of the DCC to monitor their arrival and entrainment into the DCC. We used logistic regression to model night-time arrival and entrainment probabilities with covariates that included the proportion of each diel period with upstream flow, flow, rate of change in flow and water temperature. The proportion of time with upstream flow was the most important driver of night-time arrival probability, yet river flow had the largest effect on fish entrainment into the DCC. Modelling results suggest opening the DCC during daytime while keeping the DCC closed during night-time may allow for water diversion that minimizes fish entrainment into the interior delta.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Diel activity patterns of juvenile late fall-run Chinook salmon with implications for operation of a gated water diversion in the Sacramento–San Joaquin River Delta
Series title River Research and Applications
DOI 10.1002/rra.2885
Volume 32
Issue 4
Year Published 2016
Language English
Publisher John Wiley & Sons
Contributing office(s) Western Fisheries Research Center, California Water Science Center
Description 10 p.
First page 711
Last page 720
Country United States
State California
Other Geospatial Sacramento-San Joaquin River Delta
Online Only (Y/N) N
Additional Online Files (Y/N) N