Sound production associated with reproductive behavior of Nassau grouper Epinephelus striatus at spawning aggregations

Abstract

Sound production by Nassau grouper Epinephelus striatus is described from different spawning aggregation sites in the Caribbean. Passive acoustic data and video were recorded in Belize (February 2011) and Puerto Rico (February 2012) revealing 2 distinctive sounds. The first is a pulse train sound thought to be associated with alarm or warning behavior, while the second is a tonal sound associated with reproductive behaviors, including courtship displays. The average peak frequency of the pulse train was 77.4 ± 30.3 Hz, individual pulse duration was 0.09 ± 0.02 s and the number of pulses varied from 6 to 13. For the tonal sound, the average peak frequency was 99.0 ± 33.6 Hz, and sound duration was 1.6 ± 0.3 s, ranging from 0.9 to 2.3 s. Long-term recordings at the Grammanik Bank, US Virgin Islands (February 2011) revealed variability in the daily patterns of tonal sounds during the residence time at the aggregation. Sound production was highest 7 to 8 d after the full moon between 20:00 and 21:00 h Atlantic Standard Time. The Nassau grouper courtship-associated sounds provide an advantageous tool to study the dynamics of spawning aggregations that are critical for the recovery of this Endangered species.