Salmonid Survival Studies

The Lodi Fish and Wildlife Office participates in large-scale, multi-agency, juvenile salmonid survival studies in the Sacramento-San Joaquin Delta. Presently we are conducting juvenile salmon and steelhead survival studies in the south Delta.

Our office is responsible for the study designs for the Chinook salmon studies and the acoustic tagging and release components of both the salmon and steelhead studies. The juvenile fish are from the Mokelumne or Merced River Fish hatcheries, and once they are tagged they are transported, held and released into the San Joaquin River, about 12 miles upstream of Mossdale (the southern limit of the Sacramento-San Joaquin Delta).

Our Partners

Receivers have been placed through-out the lower San Joaquin River and Delta, as far downstream as the western Delta (at Chipps Island) by our partners, the U.S. Geological Survey and the U.S. Bureau of Reclamation.

The University of Washington, our analyses partner, puts detection histories into a multi-state mark-recapture branching model to estimate reach and route survival through the Delta. We use these route and reach level survival estimates to assess various hypotheses on juvenile salmonid survival in the Delta and for identifying reaches of high relative mortality.

We have also partnered with the National Marine Fisheries Service and the California Department of Water Resources to evaluate predator control and relative predator mortality in the Delta. This information is used to inform managers and to recommend management actions to improve juvenile salmon and steelhead survival as they migrate through the Sacramento-San Joaquin Delta.

Articles and Reports

In previous years we have used coded-wire-tags to mark fish and have recovered them in sampling downstream and in the ocean fishery to estimate survival through the Delta. We have published several peer-reviewed journal articles, newsletter articles and agency reports with our partners. Articles and Reports (PDF)