Interagency Ecological Program and US Fish and Wildlife Service: Beach Seine Efficiency Study, collected by the Delta Juvenile Fish Monitoring Program, 2013-2018

Within the San Francisco Estuary, beach seining has been used since the 1970s by the U.S. Fish and Wildlife Service's Delta Juvenile Fish Monitoring Program (DJFMP) to monitor the relative abundance and distribution of juvenile Chinook salmon and other fishes of management concern occurring in near shore habitats. Over 2,000 seine samples are currently being collected throughout the San Francisco Estuary annually. Data from these surveys are used to make various water operation decisions and help inform managers on the status of fish populations within the San Francisco Estuary. By not accounting for the variability of species- and size-specific efficiency of beach seines across environmental gradients, the metrics developed by the DJFMP are likely underestimated and biased to an unknown extent. Consequently, the ability of the DJFMP to document the true occupancy of fishes for water operations and population vicissitude may be inhibited. Therefore, the first objective of this study is to estimate the species- and size-specific capture efficiency of DJFMP beach seines for fishes occurring in near shore habitats within the San Francisco Estuary. The second objective is to model the observed efficiency estimates using habitat variables to allow managers to account for incomplete detection when estimating fish abundance and occupancy from DJFMP beach seine data.