The Enhanced Delta Smelt Monitoring Program (EDSM) was initiated by the U.S. Fish and Wildlife Service in 2016. The main purpose of EDSM is to provide information about endemic Delta Smelt (Hypomesus transpacificus) population sizes and distributions within the upper San Francisco Estuary. To track the life cycle of this annual species, larval trawling with a fine-mesh (20 mm) net is conducted during the spring months, and Kodiak trawling for juveniles and adults occurs during the summer, fall, and winter months. Sampling sites are chosen via a stratified random sampling design. A minimum of two tows are conducted at each site, and field staff typically sample between 18 and 41 sites weekly. All fish collected are identified and enumerated, and a subset are measured for body length. Environmental data (water temperature, conductivity, dissolved oxygen, turbidity, depth) are also measured. In addition to Hypomesus spp., this long-term monitoring dataset can also be useful in evaluating the status and trends of other species of interest, especially pelagic fishes.

For more information: https://www.fws.gov/office/lodi-fish-and-wildlife