2017 Clifton Court Forebay Predator Reduction Electrofishing Study

The Clifton Court Forebay (CCF) Predator Reduction Electrofishing Study (PRES) was implemented in response to the National Marine Fisheries Service (NMFS) letter dated April 9, 2015, requiring that the California Department of Water Resources (DWR) immediately implement interim measure (a) of condition 3 as part of the larger effort to comply with Reasonable and Prudent Alternative (RPA) Action IV.4.2(2) of the 2009 Biological Opinion and Conference Opinion on the Long-term Operations of the Central Valley Project and State Water Project. The PRES length was three years, beginning with a pilot year effort in 2016, a 2017 effort to refine methods and determine the main factors affecting predator catch, particularly spatial patterns, and a 2018 effort focused on maximizing predator removal based on knowledge gained during the 2016 and 2017 campaigns. The PRES involved electroshocking and removing predators from CCF and transporting them to Bethany Reservoir with the goal of decreasing pre-screen loss of protected fish species with an emphasis on Chinook Salmon and steelhead. During the 2017 field effort we focused on refining methods based on lessons learned and recommendations from the 2016 effort, determining spatial and temporal patterns in predator catch rates using a standardized electrofishing sampling regime, and assessing environmental variables that may affect catch rates. In addition, we assessed factors contributing to mortality of predators transported to Bethany Reservoir and conducted preliminary analysis to evaluate evidence of black bass depletion in shoreline habitats; it is important to emphasize that predator depletion was not a PRES objective in 2017, but was informative for the 2018 season.