Grouper Tales: Use Of Acoustic Telemetry To Evaluate Grouper Movements At Western Dry Rocks In The Florida Keys

The Western Dry Rocks (WDR) area off Key West, Florida, is an open fishing area that contains a multispecies fish spawning aggregation site, but grouper spawning there has yet to be confirmed. The movements of 18 adult and subadult grouper at WDR were tracked using acoustic telemetry to determine how this area is used by grouper species and whether it contains a grouper spawning aggregation site. Tagged fish consisted of 10 Black Grouper Mycteroperca bonaci, 5 Nassau Grouper Epinephelus striatus, 2 Gag M. microlepis, and 1 Yellowfin Grouper M. venenosa. Overall, tagged grouper were more likely to be present in the WDR array during winter spawning months, with species-specific seasonal differences. Our results indicated that grouper presence increased during spawning months, although some adults and subadults were present year-round. Grouper made more movements per day during non-spawning months compared to spawning months, although the north side of WDR was the most heavily used area, regardless of the time of year. Additionally, spatial graphs of grouper movement suggested that different grouper species utilized different areas of WDR. Increased presence of grouper during spawning months suggests that the WDR area may contain a grouper spawning aggregation site, which would mean that fish species aggregate to spawn at this location year-round. The success of the Florida Keys fisheries critically depends on the protection of multispecies spawning aggregations like that potentially contained at WDR.