Grouper Moon Project – Protecting a Caribbean Icon

grouperlogoteam2A collaborative conservation program between REEF and the Cayman Islands Department of the Environment studying Nassau grouper (Epinephelus striatus) – a social and ecological corner stone of Caribbean’s coral reefs.

What are Nassau Grouper?

Normally solitary and territorial, during the winter full moons grouper travel, sometimes over great distances, and “group” together to spawn. About fifty of these spawning aggregations sites have been recorded in different places throughout the Caribbean. Historically, once discovered, grouper aggregation sites have become synonymous with fisherman aggregation sites. Due to the timing and site fidelity of the spawning aggregations and the ease with which these relative loners can be caught while congregating by the hundreds and thousands to spawn, one-third to one-half of the known Caribbean aggregation sites are now inactive. The Cayman Islands used to be home to five Nassau grouper (Epinephelus striatus) spawning sites. Today, four of these sites are dormant or depleted. But one site, on the west end of Little Cayman Island, is home to one of the last great reproductive populations of this endangered species.


Grouper Moon Project Overview

In the Winter of 2002, REEF launched a ground breaking expedition to the Cayman Islands – the Grouper Moon Project. The Project’s objectives were 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. For two weeks, a team of divers from REEF and the Cayman Islands Department of Environment visited the aggregation site and nearby reefs. 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. Components of the project include:

  • Nassau Grouper: A Caribbean Icon, Education Program – In the Fall 2011, REEF and our collaborators started development of an education program that will coincide with the Grouper Moon Project. Working with a professional educator, the program includes curricular materials and classroom lessons, as well as “meet the scientist” and “live from the field” sessions. Working in collaboration with classrooms from Cayman Prep and High School, and with funding from the Disney Worldwide Conservation Program, we piloted the program during the aggregation field season in 2012. To view a short clip of the underwater live-link, showing project scientist Dr. Brice Semmens answering questions from students while underwater, click here To find out more about this program, visit the Grouper Education Project EduBlog. You can also watch archived underwater Live-Feeds.
  • Baby Grouper Adrift! – Satellite Drifter Project – Spawning aggregations are typically located at promontories that feature a confluence of currents and waves. Why there? Using satellite drifters, we are studying the passive transport of Nassau grouper larvae spawned at the protected aggregation sites in the Cayman Islands to better understand the importance of place. This research is funded by the Disney Worldwide Conservation Program.
  • Marine Protected Areas and Spawning Aggregations – Starting in 2008, REEF and our collaborators at the Cayman Islands Department of the Environment (CIDOE) and Oregon State University (OSU) greatly expanded the conservation science research being conducted as part of the Grouper Moon Project in the Cayman Islands. The funded research, broadly titled as “The reproductive biology of remnant Nassau grouper stocks: implications for Cayman Islands Marine Protected Area (MPA) management” aims to evaluate the potential for spawning site MPAs to recover Nassau grouper stocks. This research was funded by a grant from the Lenfest Ocean Program at the Pew Charitable Trusts and expanded on the initial findings of the Acoustic Research Project that was started in 2003.
  • Acoustic Research Project – In 2003 the Cayman Island Marine Conservation Board instituted an 8-year total fishing ban on all known Nassau grouper (Epinephelus striatus) aggregation sites in the Cayman Islands.This project was conducted to provide a clearer understand of how local populations of Nassau grouper use aggregation sites, to evaluate the effect of the no-take status of aggregation sites, and in order to assess the likelihood that the closures are effective. We acoustically tagged Nassau grouper both on and off the Little Cayman west end aggregation site, and monitored movements of the tagged fish over a two year period using an array of passive autonomous hydrophones surrounding the island. This work was funded by the NOAA International Coral Reef Conservation Program. For full information, results, and to watch videos of Nassau grouper movement to and from the aggregation, click here.
    1. What proportion of Nassau grouper on the Cayman Islands use the aggregation sites receiving protection?
    2. Are there any undiscovered (and thus unprotected) aggregation sites?
    3. How often do individual fish participate in aggregations?
    4. Where do aggregating individuals come from and where do they go afterward?
    5. Does demographic status (sex and size) influence participation in aggregations?

    We acoustically tagged Nassau grouper both on and off the Little Cayman west end aggregation site, and monitored movements of the tagged fish over a two year period using an array of passive autonomous hydrophones surrounding the island. Fish tagged on the aggregation site will allow us to determine where fish go after they leave the aggregation. Fish tagged around Little Cayman outside of the aggregation season will allow us to determine the proportion of fish from the Island that attend aggregations, and the frequency of aggregation attendance by individual fishes as a function of demography. Ultimately, this information will allow us to assess the current and future impacts of protections afforded Cayman’s spawning aggregations. Additionally, the study will define an aggregation’s “sphere of influence” both geographically and demographically and will thus aid in the management of aggregations throughout the Caribbean and elsewhere.
    To view images and videos of our research methods, Click Here.

    In a nutshell, we learned that 1) all Nassau grouper attending the spawning aggregation on the West End of Little Cayman are from Little Cayman (none are traveling from other countries, or even the other two Cayman Islands), 2) all reproductively-aged Nassau grouper on Little Cayman attend the aggregation each year (and often on multiple months each year), 3) larger (older) Nassau grouper arrive earlier and stay longer at the aggregation site, and 4) the fish move back and forth off the site during the aggregation period and often will circumnavigate the island during the day.

    Videos showing the movement of each fish between the aggregation site and their home reef can be found Here.

Collaborative Team and Major Supporters

The Grouper Moon Project is a collaboration between REEF and the Cayman Islands Department of the Environment. REEF extends a huge thanks to the CIDOE staff for their tireless efforts, including Phil Bush, Bradley Johnson, Croy McCoy, James Gibb, Tim Austin, Gina Ebanks-Pietre, Keith Neale, Delwin McLaughlin, and Robert Walton. The Grouper Moon Project has continued through the years empowered by the first year’s success and the passion of project leader Leslie Whaylen Clift.

REEF volunteer project team members have included: Judie Clee, Thor Dunmire, Heather George, Dr. Steve Gittings, Tracey Griffin, Doug Harder, Brenda Hitt, Doug Kessling, Denise Mizell, Hal Peterson, Alex Score, Sheryl Shea, and Leslie Whaylen Clift. Drs. Scott and Selina Heppell from Oregon State University have been assisting with various Grouper Moon research projects since 2005. The 2010 Our World Underwater Scholar, Josh Stewart, has assisted with field efforts and outreach since in 2011 (as a Scripps Inst. of Oceanography graduate student since 2012). OSU graduate student, Stephanie Kraft-Archer assisted the project 2008-2011. On-island support from Mary Ellen Cutts is also greatly appreciated. Scripps Inst. of Oceanography graduate students, Brian Stock, Sierra Joy Stevens-McGeever, and Lynn Waterhouse, have assisted with field efforts and data management in since 2012.

Generous logistical support has been provided throughout the years by Peter Hillenbrand, as well as by local dive operators at the Little Cayman Beach Resort/Reef Divers and the Southern Cross Club. Brac Reef Resort has provided lodging support for education efforts on Cayman Brac. Cayman Airways has provided inter-island travel support. Grants from the Disney Worldwide Conservation Fund, beginning in 2011, have supported field efforts, the Baby Grouper Adrift webpage, several outreach products, and the development and continued coordination of the Grouper Education Program. A research grant from the Lenfest Ocean Program at the Pew Charitable Trusts funded the project between 2008-2011. Funding for the acoustic work was provided in 2009-2012 by the NOAA International Coral Reef Conservation Program, the J. Edward Mahoney Foundation, and PADI Project AWARE. Additional funding has been provided by hundreds of REEF members. Wayne Sullivan and his crew of the Glen Ellen has provided generous field support since 2009. Raymarine Marine Electronics donated RADAR equipment to assist the CIDOE in their enforcement efforts. To alleviate the constraints of diving deep depths on regular scuba, several other sponsors came on board to assist in the project, including Divetech and PM Gas of Grand Cayman, Silent Diving of Brockville, Ontario and Shearwater Research of Vancouver, British Columbia. LIME Cayman Islands has provided support for the live-video feeds for the Grouper Education Project since 2012. Pegasus Thrusters supported the project in 2013 through the donation of Diver Propulsion Vehicles.


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