This study uses passive acoustic recorders to detect and record white seabass spawning sounds in the wild. Initially this work was performed to test whether the spawning signals could be detected in the wild using passive acoustic techniques. Findings from the first phase of this work have shown that long-term acoustic recording systems (LARS) can be used to identify the locations and periodicities of white seabass spawning activity (Aalbers and Sepulveda, 2012). Further, this study has identified that periodic spawning occurs along several of the Southern California kelp bed communities.
The second phase of this study employs a new generation of Loggerhead Instruments DSG-Ocean Acoustic Data loggers to record sound production and spawning activity in several of the newly appointed Southern California Marine Protected Areas (MPAs). MPA sites will be continuously monitored throughout the Spring and Summer spawning seasons and compared with acoustic records from existing sites situated within similar habitats. Similar to the previous study, the DSG-recorders are set to record ambient sounds during the periods of peak spawning activity ( 2-hr period following sunset from March through July). Recorders are periodically serviced by a dive team and downloaded for subsequent analysis in the PIER laboratory.
To validate the acoustic recordings the PIER team also performs egg trawls and actively samples mature white seabass to verify fish spawning condition histologically.
We hypothesize that passive acoustic techniques can be used as a tool to assess the effectiveness of MPAs in protecting white seabass by identifying whether white seabass spawn within the protected areas and whether the newly appointed areas serve as a larval source or sink.
These factors are critical in determining whether an MPA will benefit the white seabass resource in years to come.
This work is supported by the George T. Pfleger Foundation, the Offield Family Foundation and Southern California Edison.