Grouper Moon Project Kicks Off Expanded Research Efforts

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Thousands of Nassau grouper in spawning colorations aggregated to spawn on the west end of Little Cayman Island following the full moon in January. Photo by Phil Bush.
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A Nassau grouper from Cayman Brac that will be acoustically tagged to better understand local reproductive behaviors.
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The 2008 team of Grouper Moon researchers and REEF volunteers.

Thanks to a three-year grant from the Lenfest Ocean Program at the Pew Charitable Trusts, REEF and collaborators at the Cayman Islands Department of the Environment (CIDOE) and Oregon State University (OSU) will greatly expand the conservation science research being conducted as part of the Grouper Moon Project in the Cayman Islands. The funded research, entitled "The reproductive biology of remnant Nassau grouper stocks: implications for Cayman Islands Marine Protected Area (MPA) management" will evaluate the potential for spawning site MPAs to recover Nassau grouper stocks.

In 2003 the Cayman Islands government protected all five known current and historic Nassau grouper spawning sites in the Cayman Islands. This move was motivated by the 2001 discovery and rapid depletion of a large spawning aggregation (~7000 fish) on the west end of Little Cayman. This rapid legislative response protected the west-end spawning site before all the fish were taken (~3,000 remain), and the site is now one of the largest fully-protected Nassau grouper spawning aggregations in existence. However, the other four spawning sites had previously been fished to exhaustion and are believed to be inactive, i.e. aggregations no longer occur during spawning season.

Over the next three years, REEF will continue the ongoing aggregation monitoring and acoustic research that has been conducted on the Little Cayman aggregation since 2002 and expand efforts to Cayman Brac and Grand Cayman, where historical spawning aggregations were fished out during the last ten years. Four primary research questions being asked as part of the Lenfest-funded project are: 1) Do aggregations form in regions that have been fished out? 2) If aggregations form, do the fish ultimately spawn? 3) Do these aggregations form at historic sites or somewhere else? And, 4) Does spawning at these remnant aggregations result in new recruitment?

The new research kicked into gear last month with a team of Grouper Moon scientists and REEF volunteers who conducted twelve days of field work in Little Cayman and Cayman Brac. The team visually monitored the Little Cayman aggregation, documenting the largest number of fish since the fishing ban was implemented in 2003. Spectacular mass spawning was documented at dusk seven days after the full moon. Grouper Moon scientists conducted extensive work on Cayman Brac to enable future visual monitoring on the historical aggregation site and initiate an acoustic tagging study that will facilitate a better understanding of the behaviors of Nassau grouper on an island with a limited number of reproductively-aged individuals. Later this Spring and Summer, REEF researchers, volunteers and an OSU graduate student will return to the Cayman Islands to conduct larval recruitment studies and begin acoustic tagging on Grand Cayman.

Capitalizing on the the increased breadth of research questions being asked as part of the Lenfest Ocean Program grant, the CIDOE is supporting a larval dispersal study that also kicked off this year under the guidance of Dr. Scott Heppell from OSU. Three satellite drifters were deployed at the Little Cayman aggregation site on the night of spawning. The paths will be recorded by ARGOS satellites for 45 days and the resulting data will be used to develop a larval dispersal model in collaboration with researchers from University of Miami. Check out the 2008 image gallery to see where the drifters are today.

Visit the Grouper Moon Project webpage to find out more about this critical conservation research program and the 2008 Gallery page to see images and video of the field work.

REEF extends a big thank you to the island business who continue to support this project, including the Little Cayman Beach Resort and the Southern Cross Club, as well as Peter Hillenbrand and Mary Ellen Cutts, Franklin and Cassandra Neal, and the 2008 REEF Volunteer Team -- Judie Clee, Brenda Hitt, Denise Mizell, and Leslie Whaylen.  We also greatly appreciate the continued support of our collaborative team, including the CIDOE and OSU, and the Lenfest Ocean Program at the Pew Charitable Trusts.

Design by Joanne Kidd, development by Ben Weintraub