Spatial ecology of Nassau Grouper at home reef sites: Insights from tracking a large, long-lived epinephelid using acoustic telemetry across multiple years (2005-2008)

Much of the science done by the Grouper Moon Project's collaborative research team is focused on gaining a better understanding Nassau Grouper populations in the Cayman Islands through studying their spawning aggregations; however, long-term acoustic tags (tracking pingers) allow us to gather information on how these fish behave at their home reefs outside of the spawning season. Nassau Grouper are known to be solitary and territorial. But during winter full moons, the fish leave their home site and travel, sometimes long distances, to a spawning aggregation, where they stay for up to 14 days. In this study, Grouper Moon scientists used tagging data to look at movement behavior and vertical habitat use. They found that most Nassau Grouper tend to return to the same home reef following spawning, but that the areas occupied at home reefs can change through time. In particular, they found that larger fish tend to occupy deeper areas than smaller fish, and fish will generally move to deeper reef areas over time. They also found that Nassau Grouper are more likely to be active at dawn and dusk than other times of the day, likely due to feeding activities. This information is adding to what we know about this iconic species, and will help support management of Nassau Grouper populations throughout the Caribbean. To find out more about the Grouper Moon Project, visit www.REEF.org/groupermoonproject.