Our Grouper Moon Project team returned to the Cayman Islands around the full moon in February for another month of research on the Nassau Grouper spawning aggregation on the west end of Little Cayman. Because this year was a "split moon" year, we weren't quite sure whether the major spawning activity would happen in January or February. While a few thousand fish showed up at the spawning aggregation in January, there was no spawning activity - but the fish made up for it in February. Many thousands of Nassau Grouper were present at the site, with spawning starting just two days after the full moon - the earliest our team has even documented it! Because the fish do not stay at the aggregation site longer than three or four days after they start spawning, the team worked hard to get our annual monitoring done in the condensed time the fish were present. Our team documented populations and fish sizes, and collected eggs from the spawn to conduct water temperature experiments. This was the 20th year of the Grouper Moon Project, a collaborative conservation science effort between REEF and the Cayman Islands Department of Environment, with help from Scripps Institution of Oceanography and Oregon State University, and many local businesses including Southern Cross Club, Peter Hillenbrand, Little Cayman Beach Resort, and Reef Divers. To learn more, see amazing underwater footage of the Nassau Grouper aggregation, and read about what makes this project a blueprint for conservation success in the Caribbean, visit www.REEF.org/groupermoonproject.