Soundscape fishing: Spatial variability in a low-frequency fish chorus in the southern California kelp forest

The kelp forests off the coast of southern California support a diverse assemblage of fishes, many of which are known to produce sound. Here, the spatial variability of a low-frequency (325–545 Hz) fish chorus recorded at three sites near the kelp forests off La Jolla, California, is described. This chorus dominated the dusk soundscape at all sites in May/June 2015, 2016, and 2017. During these times, spectral levels around 400 Hz increased by approximately 30 dB over a period of 3 h between 19:00 and 22:00 local time. The location of the fish chorus was estimated during each year using beamforming and time difference of arrival (TDOA) techniques on signals recorded by either a two-element 30-m aperture linear seafloor array or an array with four-elements, 20-m aperture in a tetrahedral-shaped configuration. This location was relatively constant during the chorusing each night. Environmental factors such as temperature, macroalgae assemblage and bottom cover, and geological features were investigated as p...