We are excited to share the latest scientific paper from the Grouper Moon Project. The study, published last month in the journal Proceedings of the Royal Society B, addresses the question of where fertilized eggs go after being released by Nassau Grouper at their spawning site off the west end of Little Cayman. This study used state-of-the-art technology, including satelite-tracked drifters, an underwater microscope, and a glider to raise and lower the instruments. While reproductive success and the final destination of the grouper eggs can vary from year to year, the results highlight how local conservation measures by the Cayman Island government to protect Nassau Grouper are boosting local populations, and providing spillover benefits to neighboring islands. It is also an example of the power of collaboration, a key component to the conservation success story of the Grouper Moon Project. Scientists from several departments at Scripps Institution of Oceanography (UC San Diego) led the work, who were assisisted by REEF's Grouper Moon field team and supported in the field by the Cayman Islands Department of Environment vessels and crew.
On spawning nights in 2017, researchers physically tracked clouds of tiny, transparent Nassau Grouper eggs with an underwater microscope developed by scientists at Scripps Oceanography. Results show that fertilized eggs from Little Cayman floated back onto reefs on the island. Drawing on these direct observations and ocean current data collected on spawning nights at Little Cayman in previous years, the authors also used a computer model to investigate where the fertilized eggs likely went in 2011 and 2016. The model predicted that many of the baby Nassau Grouper ended up back at Little Cayman in 2011, a suggestion that dovetails with prior research (see here), showing that the 2011 reproductive season led to a massive population increase around Little Cayman (see here). For 2016, the model predicted that currents carried some fertilized eggs to the nearby island of Grand Cayman.