Effectiveness of a Delta Cross Channel Graduated Field Electrical Fish Barrier to Reduce Movement of Adult Fall-run Chinook Salmon from the Mokelumne River into the Sacramento River, CA

Project ID: 554
Principal Investigator: Zak Sutphin
Research Topic: Ecosystem Needs
Funded Fiscal Years: 2015 and 2017
Keywords: electrical fish barrier, delta cross channel, chinook salmon, central valley project improvement act, mokelumne river

Research Question

What is the effectiveness of a graduated field electrical fish barrier to reduce movement of adult fall-run Chinook salmon from the Mokelumene River, through the Delta Cross Channel Gates, and into the Sacramento River, CA?

Need and Benefit

California's Central Valley fall-run Chinook salmon (Oncorhynchus tschawytscha) have experienced declines in abundance over the last century (Yoshiyama 1998; Moyle 2002), punctuated by alarmingly low escapement in recent years (Lindley et al. 2009). As a result, Central Valley fall-run Chinook salmon have been listed as a species of special concern under the Endangered Species Act. Mokelumne River fall-run Chinook salmon contribute to a significant portion of the overall returning adult spawners in Central Valley's San Joaquin River system, and though abundance of spawning adults in the Mokelumne River have recently rebounded, the success of Mokelumne River salmon relies heavily on hatchery produced introductions from Mokelumne River Fish Hatchery (East Bay Municipal Utility District; Bilski and Rible 2011). Coded wire tag data from the Central Valley Constant Fractional Marking Program (CFM) suggests a portion of hatchery released Mokelumne River fall-run Chinook salmon do not return to their prenatal system, but stray into Sacramento River, and ultimately, tributaries of the Sacramento River (Kormos et al. 2012). Though there are a multitude of migrational pathways upstream migrating adult Mokelumne River fall-run Chinook salmon could take to stray into the Sacramento, experimental Delta Cross Channel (DCC) gate closures in 2010 and 2011, resulting in reduced straying into the American River by reportedly > 50%, suggest traversing through the DCC likely contributes to straying. The DCC and associated gates, located in Walnut Grove, CA, operate to maintain salinity standards at the Central Valley Project and State Water Project export pumps by drawing fresh water from the Sacramento River into the South Sacramento-San Joaquin Delta (Delta) via the Mokelumne River. Open DCC gates and diverted Sacramento flows may provide a positive stimulus attracting adult Mokelumne River origin fall-run Chinook salmon, resulting in straying away from their prenatal spawning grounds into the Sacramento River system and major tributaries (i.e., American River). Some straying is natural and is generally perceived as beneficial, as it promotes genetic diversity (Quinn 1993; Marston et al. 2012). However, straying as a result of anthropogenic influences or inordinate levels of straying may contribute to poor returns of adult fish to the Mokelumne River, impacting genetic integrity and hatchery operations.

In an effort to promote the continued operation of the DCC and meet South Delta water quality standards, while minimizing straying of adult salmon, an instream electrical barrier system (e-barrier) will be installed and tested to determine the efficacy of the system to minimize movement of adult upstream migrating Chinook salmon from the Mokelumne River to the Sacramento River through the DCC. If continued efforts, aimed at specifically quantifying straying of fall-run Chinook salmon through the DCC, determine there are significantly more Mokelumne River Chinook salmon straying through the DCC then Sacramento River (and tributaries) Chinook salmon trying to return to their prenatal systems, this technology would have the benefit of precluding any DCC gate closures during October, and eliminate some concerns regarding water quality issues during dry years.

Contributing Partners

Contact the Principal Investigator for information about partners.

Research Products

Bureau of Reclamation Review

The following documents were reviewed by experts in fields relating to this project's study and findings. The results were determined to be achieved using valid means.

Effectiveness of a Delta Cross Channel Graduated Field Electrical Fish Barrier to Reduce Movement of Adult Fall-run Chinook Salmon from the Mokelumne River into the Sacramento River, CA (final, PDF, 759KB)
By Michael J. Horn, Jarod Hutcherson, Zachary Sutphin
Research Product completed on September 30, 2017

This research product summarizes the research results and potential application to Reclamation's mission.

Effectiveness of a Delta Cross Channel Graduated Field Electrical Fish Barrier to Reduce Movement of Adult Fall-run Chinook Salmon from the Mokelumne River into the Sacramento River, CA (final, PDF, 759KB)
By Michael J. Horn, Jarod Hutcherson, Zachary Sutphin
Research Product completed on September 30, 2017

This research product summarizes the research results and potential application to Reclamation's mission.


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Last Updated: 4/4/17