The Enhanced Delta Smelt Monitoring Program (EDSM) was initiated by the U.S. Fish and Wildlife Service in 2016. EDSM focuses on providing real-time data to help managers respond to population patterns of Delta Smelt within the upper San Francisco Estuary, primarily by providing estimates of Delta Smelt distribution and abundance. The dataset can also be useful in evaluating habitat use and behavior patterns of this species and other fish species of interest. Sampling is done year round via Kodiak trawls and larval (“20-mm”) gear to sample Delta Smelt across most life stages. Sites are chosen via stratified random sampling. Over the course of a week, field crews sample between 18 and 41 random sites. A minimum of two tows are conducted at each site. All fish collected are identified (in the field when possible, in the lab for early life stages), measured, enumerated, and recorded. In addition to fish information, environmental data are collected for each sampling event. For more information: https://www.fws.gov/project/enhanced-delta-smelt-monitoring-program