Delta Juvenile Fish Monitoring 

The Delta Juvenile Fish Monitoring Program was established in the 1970s to monitor juvenile salmon abundance in the San Francisco Bay-Delta using trawling and beach seine nets. Since then the DJFMP has expanded its objective and sampling efforts, most significantly in 2016, when the Enhanced Delta Smelt Monitoring Program was initiated as part of DJFMP.

Today, the DJFMP continues to document the relative abundance, distribution and survival of juvenile salmonids and other fishes in the lower Sacramento and San Joaquin rivers, Delta and San Francisco Bay for the protection, recovery and management of naturally produced salmonids and other native species in the Central Valley of California.

Monitoring Data

All monitoring data are collected by the Lodi Fish and Wildlife Office.

Daily and weekly summary reports are available in the Lodi FWO Monitoring Data collection. Raw preliminary data files are also available. Some of the more common data requests, such as Chinook salmon, steelhead and pelagic organism decline species (e.g., Delta smelt, longfin smelt, threadfin shad and striped bass) catch data — by survey as well as the Chipps Island survival calculations — have also been compiled.

If you would like additional information or want to request specific data or a specific format, please contact fish biologist Jonathan Speegle at or 209-334-2968, ext. 322. Custom data requests will be handled as soon as possible; however, response times may be delayed under certain circumstances. We encourage users to contact the data managers to discuss what dataset is best suited to your needs.

Complete data files that have undergone final quality checks are available on the Environmental Data Initiative Data Portal. Type DJFMP or EDSM into the search bar to access the data sets and accompanying program metadata. These files are updated periodically as final quality-assurance and quality-control measures are completed.

Some of our research published in peer-reviewed journals can be viewed at the links below.

Peer-Reviewed Journal Articles

Utility of boat electrofishing for sampling fishes in the Sacramento-San Joaquin Delta, San Francisco Estuary and Watershed Science, March 2021

Resistance and resilience of fishes to drought in the San Francisco Estuary, Ecological Applications, February 2021

Water temperature influences timing and size of migrating juvenile Chinook salmon in the Sacramento-San Joaquin Delta, Ecological Applications, March 2019

Changes in the nearshore fish community in the Sacramento-San Joaquin Delta, PLOS ONE, January 2017

Abundance, distribution, and habitat of the non-native Mississippi silverside, San Francisco Estuary and Watershed Science, March 2016

Relationship between juvenile Chinook salmon survival and Sacramento-San Joaquin Delta water exports, North American Journal of Fisheries Management, January 2010