REEF Gearing Up For Another Year of Nassau Grouper Aggregation Research

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Approximately 3,500 Nassau grouper, an endangered species, gather off Little Cayman Island during winter full moons to reproduce. Photo by Scott Heppell.
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A light trap deployed underwater in Little Cayman to study the recruitment of larval Nassau grouper.

REEF scientists, volunteers and collaborators will be in the Cayman Islands next month for the 8th year of the Grouper Moon Project. Thanks to a three-year grant awarded last year by the Lenfest Ocean Program of the Pew Charitable Trusts, REEF has greatly expanded the critical conservation research conducted as part of this study of Nassau grouper spawning aggregations. We will have teams on all three of the Cayman Islands conducting field research as part of the project, “The reproductive biology of remnant Nassau grouper stocks: implications for Cayman Islands Marine Protected Area (MPA) management”. The Little Cayman team will continue the long-term visual monitoring of the large aggregation located there. Work on Grand Cayman and Cayman Brac will focus on studying the remnant aggregations that remain on these islands after years of fishing. There is currently a harvest ban in effect for all aggregations in the islands. This ban is set to be lifted in 2011 unless the extension of the protections are warranted.

Despite logistical complications, weather anomalies and difficulties locating fish, the Grouper Moon Project had a successful year of field-work in 2008. The team conducted preliminary work on Cayman Brac and Grand Cayman, tagging Nassau grouper with pinger acoustic tags and then installing hydrophone arrays to track the movements of those tagged individuals. Studies were also conducted to better understand the patterns of recruitment by larval and juvenile Nassau grouper to the islands. In addition, members of our team attended major scientific conferences both nationally and internationally, and presented aspects of our research and findings to date.

In the Winter of 2002, REEF launched the Grouper Moon Project with a ground breaking expedition to observe the Nassau grouper spawning aggregation off the western tip of Little Cayman and to develop a protocol for monitoring their numbers and activity at the site. Since that first year, REEF has coordinated annual efforts to monitor and study the Little Cayman Nassau grouper aggregation. The project has grown in scope to include an ambitious acoustic tagging research project, juvenile habitat and genetics studies, and early results have been published in the scientific literature. This work is a collaboration with the Cayman Islands Department of the Environment and researchers from Oregon State University.

To find out more, visit the Grouper Moon Project webpage.

Design by Joanne Kidd, development by Ben Weintraub