Fish Losses Due to Predation Workshop

One of the goals of the CALFED Science Program is to provide authoritative and unbiased descriptions of scientific knowledge. To fulfill this goal, the Science Program holds workshops designed to provide a forum for discussions and the exchange of information among Scientists, Stakeholders, Agency Staff, and the public about topics important to the region. These workshops synthesize the science related to complex problems and provide advice for undertaking specific complex tasks in support of Delta planning and decision-making.

The California Bay-Delta Authority (CBDA) hosted a 2-day workshop in June 2005 to examine technical issues associated with the losses of sensitive fish species to predators at the Sacramento-San Joaquin Delta intakes to the state and federal water projects. Estimating losses to predators (with the predators being mainly sub-adult striped bass) is part of a process used to calculate take (total number of fish lost to the system) of four races of juvenile Chinook salmon at the project intakes. These take levels are then used as part of the process to determine if project pumping should be reduced to protect the fish as well as to evaluate impacts of project pumping on these fish. The projects provide water to California's cities and farms, thus pumping reductions can affect reliability of this critical component of State's water supply.

Fish Losses Due to Predation at the State Water Project and Central Valley Project Delta Intakes - The final reports and supporting materials for the CALFED Technical Workshop held on June 22 and 23, 2005

The workshop goals were to:

  1. Examine the technical basis for present predation loss calculations.

  2. Determine if additional studies are needed to refine the loss estimating procedures and if they can be expanded to include other sensitive species such as steelhead and delta smelt.

  3. Assess the potential impacts and benefits of proposed physical and operational modifications at the project intakes and how these changes may affect losses to predators.

The CBDA and the California Department of Water Resources assembled a five person expert panel to assist the workshop attendees sort out the difficult technical questions associated with losses to predators. The panel was asked to provide an independent assessment related to the goals.

Workshop documentation

It was decided to provide a complete documentation for the workshop including a workshop summary by Wim Kimmerer and Randall Brown, the expert panel report, the PowerPoint slides from the workshop presentations and the technical reports from which much of the information related to predation in the SWP's Clifton Court Forebay has been drawn.

The workshop PowerPoint presentations

Supporting technical reports