Ending the day with a song: Patterns of calling behavior in a species of rockfish

Similar to birds, fish produce sound to attract mates and repel rivals. At the height of the mating season, these calls form a significant part of the marine soundscape. Even though this phenomenon is widespread in fish species, not much is known about fish calling behavior. We investigated the seasonal, lunar and diel patterns of calling behavior of bocaccio (Sebastes paucispinis), a species of rockfish, in the Channel Islands National Marine Sanctuary, on the west coast of the United States. We deployed acoustic recorders at five sites in the Sanctuary, at depths of 21–156 m, for a period of a year. We extracted bocaccio calls using a detection algorithm and related calling patterns to time of day, lunar illumination and time of year. Besides showing correlations with season and lunar illumination, bocaccio calls were mostly produced at night, with clear peaks at crepuscular time periods. The diel calling pattern showed correlations with site depth, possibly due to vertical migration of fish through the course of the night. Describing and understanding patterns of fish calling behavior can provide insight into communication, habitat preference, mating behavior, or animal density of these species as well as help characterize the acoustic environment that sustains them.