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Sound production in red grouper Epinephelus morio is useful for monitoring their distribution and behavior.

Sound production by goliath grouper Epinephelus itajara was characterized on 2 aggregation sites in the Gulf of Mexico off the southwest coast of Florida, which are likely to be spawning sites, based on the presence of fish with ripe gonads. Goliath grouper produced predominately lowfrequency single-pulse sounds with dominant frequencies around 60 Hz. Long-term acoustic recordings documented that sounds were most frequently produced between 01:00 and 03:00 h. Sound production had a lunar periodicity, with reduced levels occurring for several days around the full moon. A single goliath grouper was implanted with an acoustic telemetry transmitter that indicated the depth of the fish. This fish remained on the aggregation site for all but 1 d of the 2 mo record and was located near the bottom (46 m) for the majority of the time. Several forays to shallower depths were detected, most of which occurred near midnight and 03:00 h. These short-duration shallow-water forays could possibly indicate spawning ascents. The combination of passive acoustics and active acoustic telemetry indicates that efforts to document spawning should be concentrated around midnight. The prolific sound production of goliath grouper will allow large spatial and temporal scale mapping and monitoring of aggregation sites. KEY WORDS: Goliath grouper · Epinephelus itajara · Sound production · Passive acoustics · Fish tracking · Depth distribution · Spawning aggregations Resale or republication not permitted without written consent of the publisher OPEN PEN ACCESS CCESS Contribution to the Theme Section 'Range-wide status and conservation of the goliath grouper'Endang Species Res 7: 229-236, 2009 grouper that were thought to be female (Colin 1990). To our knowledge, spawning has not been observed in this species.Goliath grouper form aggregations on reefs and shipwrecks where they are suspected to spawn (Sadovy & Eklund 1999, SEDAR6 2004 during June through December, with peak spawning activity occurring from July through September in the eastern Gulf of Mexico (Bullock et al. 1992). While tagging studies have demonstrated site fidelity at such locations (Koenig et al. 2007), it is unclear whether spawning migrations to certain key sites bring larger numbers of goliath grouper together from a broader area, as has been documented for a variety of grouper species (e.g. Sadovy 1994). The Southeast Data Assessment and Review 6 workshop (SEDAR6 2004) highlighted the identification of spawning locations, duration and periodicity of goliath grouper as important research needs.Goliath grouper is critically endangered over its entire range (Chan Tak-Chuen & Padovani Ferreira 2006), which extends from west Africa to the Pacific coast of Central America, south to Brazil and north to North Carolina. The species has been fully protected in the southeastern USA since the early 1990s, and is showing strong signs of recovery, especially in southwest Florida, where the present study was conducted. Key factors in recovery include extensive high quality...

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