Abstract

Over the last decade, researchers have increasingly used passive acoustics to discover and monitor fish spawning aggregations (FSAs) in terms of both species presence and relative abundance (Appeldoorn et al. 2013, Mann et al. 2010, Nelson et al. 2011, Rowell et al. 2011, Rowell et al. 2012, Schärer et al. 2012a, 2012b, 2014). A growing library of species-specific vocalizations made on spawning sites has aided these survey efforts. However, because most Caribbean reef FSAs occur at remote locations and in deep (> 40 m) water, coupled visual and acoustic observations during spawning have proven difficult to collect. Since 2002, scientists and volunteers from the Reef Environmental Education Foundation (REEF) and the Cayman Islands Department of Environment (CIDOE) have been studying a shallow (30 m) and easily accessible multi-species FSA on the west end of Little Cayman, Cayman Islands, through the Grouper Moon Program (GMP; www.reef.org/groupermoonproject). In January 2013, GMP personnel deployed a continuously recording passive acoustic hydrophone at the FSA site, and subsequently monitored nightly spawning behaviors of aggregating species through both visual surveys and underwater video over a 5-day period. During this period the hydrophone recorded vocalizations from Nassau grouper (Epinephelus striatus), red hind (Epinephelus guttatus), black grouper (Mycteroperca bonaci) and yellowfin grouper (Mycteroperca venenosa).

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