Grouper Moon Project Overview and Research Components

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.

A summary of all scientific papers that have resulted from the project is here.

Monitoring Population Size at the Spawning Aggregation - At the core of the Grouper Moon Project is tracking population change through time. In 2020, findings from this work (Waterhouse et al) were published in the journal Proceedings of the National Academy of SciencesRecovery of critically endangered Nassau grouper (Epinephelus striatus) in the Cayman Islands following targeted conservation actions.

Other research components of the project include:

Size Structure of Aggregating Nassau Grouper - Since the early days of the Grouper Moon Project, researchers have been recording sizes of individual Nassau Grouper at the spawning sites in the Cayman Islands. This was initially accomplished with dock-side sampling, measuring fish that were caught by fishermen at the aggregation. Once the Grouper Moon Project started doing field work at the spawning sites, researchers on scuba used laser calipers paired with video. These lasers were a set distance apart, which could then be used to measure each "lasered" fish in photos processed from the video. In 2017, new stereo-video technology was introduced that enabled researchers to use paired cameras at a set distance apart (recording in stereo vs. mono) to record the aggregation, which can then be post-processed to measure all fish in each video frame. In 2022, the stereo-video technology was modified to use Intel's RealSense camera, which uses depth of field to estimate size. Findings from this research have been published (Stock et al 2021; Heppell et al 2012)

Genetics of Nassau Grouper - Genetic material taken from Cayman Island Nassau Grouper has been used in a suite of Caribbean-wide studies to understand patterns of genetic connectivity, as well as to contribute to fisheries management and conservation. Findings from this research has been published (Bernard et al 2016Jackson et al 2014Jackson et al 2012)

Active Acoustic Research to Study the Soundscape - From 2015 to 2107, the Grouper Moon Project collaborated with Scripps Institution of Oceanography researchers, Katherine Wilson and Ana Širović, on the soundscape of the Little Cayman spawning aggregation. As part of this work, our team deployed a hydrophone array at the Nassau Grouper spawning aggregation site with the objectives to 1) localize the sounds produced by aggregating Nassau Grouper to examine the dynamics of the aggregation overnight and during the periods that are not monitored by our Grouper Moon research team, and 2) analyze the soundscape and the characteristics of all the known sounds produced by grouper at this multi-species spawning aggregation to study the sound communication of these fishes. The latter objective included localizing these sounds to measure sound levels and estimate detection and eventually communication ranges for the sounds of these species. Findings from this research have been published (Wilson et al 2022; Wilson et al 2020; Wilson et al 2019)

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 studied the passive transport of Nassau Grouper larvae spawned at the protected aggregation sites in the Cayman Islands to better understand the importance of place. The original drifter research was funded by the Disney Conservation Fund. To learn more about the 2011 Baby Grouper Adrift! project, click here.

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.

Passive Acoustic Research Project - In 2003 the Cayman Island Marine Conservation Board instituted an 8-year total fishing ban on all known Nassau Grouper 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 more information, results, and to watch videos of Nassau Grouper movement to and from the aggregation, click here. Results of this research have been published (Blincow et al 2020; Semmens et al 2005)

In addition to research and science outlined here, a comprehensive education program serves as companion to the Grouper Moon Project.

Nassau Grouper: A Caribbean Icon, Education Program - In the Fall 2011, REEF and our collaborators started development of an education program that coincides 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. It has been ongoing since then, and each year several Caymanian schools participate. To view a short clip of one of the underwater live-link session, 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.