The Grouper Moon Project is a conservation science partnership between REEF and the Cayman Islands Department of Environment (DoE), with scientists from Scripps Institution of Oceanography at UC San Diego and Oregon State University. The project is aimed at studying Nassau Grouper (Epinephelus striatus) - a social and ecological corner stone of Caribbean's coral reefs. Since 2002, our team has studied the Nassau Grouper spawning aggregations in the Cayman Islands, which hosts some of the last and largest reproductive gatherings of this endangered Caribbean reef fish. Our efforts have resulted in the successful recovery of Nassau Grouper populations in the Cayman Islands, and the project highlights the value of collaborative efforts for conservation success.
As the winter full moon approaches and we prepare to head in the field for the 2025 field season, we wanted to share some of the highlights of Grouper Moon research findings over the last 23 years. Read on to learn more. You can also visit www.REEF.org/groupermoonproject to see details on the education programming, scientific studies, and documentaries that have been done on the project.
One of the earliest scientific papers that was published from the project was in 2004, a few years after REEF staff member, Leslie Whaylen, happened to be on Little Cayman in 2001 leading a REEF Field Survey Trip shortly after fishermen discovered an aggregation of Nassau Grouper off the west end of the island. Approximately 2,0000 fish were harvested over 10 days, from a population that was later determined to be about 9,000 fish. After meeting with the Cayman government, the Grouper Moon Project was formed. Leslie led the first field effort in 2002 and the Cayman government instituted an initial 8-year harvest ban at the aggregation later that year after another 2,000 fish were harvests. Leslie and co-authors documented the characteristics of the newly discovered Nassau Grouper spawning aggregation and reported their findings in a paper published in the journal Environmental Biology of Fishes. They provided visual and video documentation of four nights of spawning of Nassau Grouper, the description of crepuscular and lunar movements and color phase shifts in the grouper, and the documentation of courtship/spawning behavior in ten additional species.
A few years later, in 2007, lead scientist for the project, Dr. Brice Semmens, and project partners published a paper that explored why Nassau Grouper had declined so precipitously in the Caribbean over the last few decades and what could be done to reverse the trend. The discussion leaned heavily on early findings from the Grouper Moon Project. This study, titled "Charting a Course for Nassau Grouper Recovery in the Caribbean: What We’ve Learned and What We Still Need to Know" was presented at the 60th Gulf and Caribbean Fisheries Institute Meeting.
In 2020, almost two decades after the aggregation was first discovered, a landmark paper was published in the prestigious Proceedings of the National Academy of Sciences that presented our findings of conservation success for endangered Nassau Grouper. Results of the analysis showed that on both Little Cayman and Cayman Brac, Nassau Grouper spawning aggregations have more than tripled in response to adaptive management by the Cayman Islands government over a decade. These management actions were a direct result of research conducted as part of the Grouper Moon Project.
The Grouper Moon Project is the Caribbean’s oldest continuous grouper spawning aggregation research program, and represents one of the most advanced, multi-faceted tropical fisheries research programs in the world. Scientific products stemming from the project aim to support science-informed policies that will facilitate healthy grouper fisheries in the Cayman Islands in the coming years, while maintaining the Cayman Islands’ global leadership in collaborative tropical fisheries research and management. Since 2001, REEF and our collaborators have published 22 scientific papers sharing results from the research. All can be found at www.REEF.org/grouper-moon-project-publications.