In 2026, the Grouper Moon Project entered its 24th year, marking more than two decades as the Caribbean’s longest-running continuous research program focused on Nassau Grouper, Epinephelus striatus, spawning aggregations. Led by REEF in collaboration with the Cayman Islands Department of Environment (DoE), Scripps Institution of Oceanography at UC San Diego, and Oregon State University, the project has become one of the most advanced, multi-faceted tropical fisheries research efforts in the world.
But last year, something unprecedented happened. For the first time in the project’s history, the Nassau Grouper didn’t show up. Despite extensive surveys at the known aggregation site and around Little Cayman, researchers were unable to locate the fish. The absence raised urgent questions: Had the fish shifted spawning sites? Was our timing off? Or was something else at play entirely?
This year, the team was eager, and hopeful, to find answers. We are delighted to share the Nassau Grouper were back. In their thousands.
With the fish returned, the team set out to put new technology to work. A key goal this season was collecting population data using cutting-edge tools, including facial recognition AI models being developed through REEF’s Grouper Spotter platform, alongside length measurements gathered using REEF’s latest SMILE (Size Matters: Innovative Length Estimates) laser prototype.
Length data is a critical piece of the conservation puzzle. It helps scientists and the Cayman Islands Government detect recruitment pulses, periods when large numbers of young fish enter the spawning population. Recovery for long-lived species like Nassau Grouper is not linear. It often occurs in bursts separated by many years. This reality underscores the importance of long-term management and sustained protection for successful population recovery.
However, collecting data this year was not without challenges. A winter cold snap along the U.S. East Coast extended into the Caribbean, bringing unusually cold air, rough seas, and strong currents to the Cayman Islands. Several dive days were lost to unsafe conditions, and when dives were possible, researchers contended with powerful currents at the aggregation site, sometimes only manageable as small teams on Diver Propulsion Vehicles. Despite the conditions, the research team gathered hundreds of hours of video footage for analysis, collected thousands of Nassau Grouper eggs for genetic research, and collected environmental DNA samples for potential population detection proxies.
One of the standout successes of the 2026 field season was the education program. The project culminated in three livestreamed webchats connecting Grouper Moon scientists with students across the Cayman Islands. More than 12 classrooms participated, including a live underwater broadcast from the coral reef. These sessions gave students a rare, real-time window into marine research, and opportunities to ask marine scientists questions about grouper ecology and life as a marine scientist. Recordings of the livestreams can be viewed at www.youtube.com/wespeakfish.
To learn more about the Grouper Moon Project, including research findings, education programs, and documentaries, visit www.REEF.org/groupermoonproject.