Interagency Ecological Program: Sacramento-San Joaquin Delta boat electrofishing survey during the critical drought of 2014

The objective of this study was to assess the relative distributions
of non-native resident fishes occurring in littoral habitats during
the drought year of 2014 within the western and northern portion of
California's Sacramento-San Joaquin Delta (Delta), USA. A number of
non-native resident fish species (e.g., black bass, Micropterus spp.)
in the Delta have undergone remarkable increases in density in the
early 2000s and they are potential predators of endangered native
fishes such as Chinook Salmon (Oncorhynchus tshawytscha) and Delta
Smelt (Hypomesus transpacificus). The Delta makes up the tidal
freshwater portion of the San Francisco Estuary in California;
however, the critically dry year of 2014 caused a considerable
intrusion of salinity field within this region and may have caused a
shift in the resident fish community. To evaluate the response of
non-native resident fishes to this salinity intrusion, a boat
electrofishing survey was conducted in November of 2014 in the western
and northern part of the Delta by the United States Fish and Wildlife
Service, Lodi, California Office as part of the Interagency Ecological
Program for the San Francisco Estuary. Replicate sampling was done for
each site in this study in order to account for false zeroes through
the estimation of capture probability.