Grouper Moon Project 2010

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Over 4,000 Nassau grouper can be found on the Little Cayman spawning aggregation. This is the largest known aggregation of this endangered reef fish. Photo by Phil Bush.
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Spawning was documented during four nights on the Little Cayman site. Photo by Brice Semmens.
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REEF Board of Trustee member, Heather George, and REEF Advisory Panel Member, Dr. Steve Gittings, helped with this year's field effort.
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Denise Mizell, along with Wayne Sullivan and the crew of the Glen Ellen, made up the Grand Cayman team.

Since 2001, REEF has led the Grouper Moon Project, a multi-faceted, collaborative research effort with the Cayman Islands Department of the Environment (CIDOE) aimed at better understanding Nassau grouper reproduction and the role that marine reserves can play in the long-term protection of this endangered species. Earlier this month, we had researchers and volunteers in the field for two weeks to conduct field research on spawning aggregations in Grand Cayman and Little Cayman. The site on Little Cayman represents one of the largest known remaining aggregations of Nassau grouper; our research will provide valuable guidance to both the Cayman Islands government and others throughout the Caribbean on how to best protect this important coral reef fish.

In 2003 the Cayman Island Marine Conservation Board instituted an 8-year fishing ban on Nassau grouper at all known aggregation sites in the Cayman Islands (both current and historic). This followed the discovery by fisherman of 7,000 aggregating Nassau grouper on the west end of Little Cayman in 2001 and the subsequent harvest of 4,000 of those fish over two spawning seasons. At the time, all other known Nassau grouper aggregations in the Cayman Islands had become inactive due to over-harvest. Thanks to a three-year grant awarded in 2008 by the Lenfest Ocean Program of the Pew Charitable Trusts, REEF is conducting research through the Grouper Moon Project to evaluate the current status of the Cayman Islands spawning aggregations and the effect of these harvest protections -- “The reproductive biology of remnant Nassau grouper stocks: implications for Cayman Islands Marine Protected Area (MPA) management”.

The broad goals for the 2010 spawning season were to continue monitoring recovery in the large spawning aggregation on Little Cayman, and to expand research into the fate of remnant spawning aggregations on Grand Cayman; aggregations on this island were fished to exhaustion in the recent past. REEF continued education and outreach efforts through public talks about spawning aggregations and the Grouper Moon research. As the sunset provision on the current legislation nears, REEF is working closely with the Cayman Islands government to translate the findings from our research into effective long-term protections. I spent time with the Honorable Mark Scotland, the Minister of Health, Environment, Youth, Sports & Culture, which oversees the Department of Environment in the Cayman Islands, discussing the project, our ground-breaking results, and recommendations for the future of this iconic species.

2010 Aggregation Season Results Summary

The Little Cayman team continued the long-term monitoring of this aggregation, which includes counting the number of fish that show up, estimating the size of the fish, and recording the timing and amount of spawning observed. The REEF research team uses lasers mounted on a video camera to record sizes of fish. If you would like to see what the Little Cayman aggregation looks like during the day, check out this video on YouTube. You will see the laser marks on the fish. Note that these are all Nassau grouper, just in different spawning colors. The team estimated that the number of fish showing up at the aggregation is approaching 4,000. We are also seeing a decrease if average size, which indicates that younger fish are starting to show up (good news!). Spawning was observed on four consecutive nights, starting 4 days after the full moon.

The Grand Cayman team’s primary goal was to document the remnant Nassau grouper aggregation on the East End of Grand Cayman and hopefully observe spawning. The status of this aggregation was initially documented by a Grouper Moon team in 2009. This year, with a lot of help from our partners at CIDOE and Wayne Sullivan and his crew aboard the Glen Ellen, REEF volunteer Denise Mizell was able to head up this critical component of our research. While several hundred fish were found at this historical spawning site, spawning was not documented. Unfortunately, we believe that fisherman were illegally fishing on the aggregation when our team was not on site. It is possible that this disturbance prevented the fish from spawning. This is disappointing news, but we are hopeful that the Cayman Islands government will pass revised legislation and provide more enforcement before next spawning season in order to protect the few remaining Nassau grouper on Grand Cayman.

Why Does This Matter?

Nassau grouper are not just icons of the Caribbean; they are a social and ecological cornerstone of the region’s coral reefs. Historically, Nassau grouper represented one of the region’s most economically important fisheries. Unfortunately, due to intense harvest on spawning aggregations, their populations have dwindled to a fraction of their historic numbers. The species became the first Caribbean reef fish to be listed as endangered by the International Union for the Conservation of Nature (IUCN) and the species is candidate listed under the US Endangered Species Act. The precipitous decline in mass spawning aggregations of Caribbean grouper species has been well documented. The majority of known Caribbean aggregation sites are now inactive due to the ease with which aggregating species are caught. And those that are still active contain significantly fewer fish than the 10s of thousands that historically gathered at these special places.

As part of our work on the Grouper Moon Project, REEF will continue to develop a comprehensive assessment of the status of the Cayman Island’s Nassau grouper spawning population as a guide for future Nassau grouper restoration and conservation policy.

Collaborators and Supporters Who Make This Project Possible

REEF would like to thank our collaborators at the Cayman Islands Department of the Environment, specifically Phil Bush, Bradley Johnson, Croy McCoy, James Gibb, Tim Austin, Gina Ebanks-Pietre, Keith Neale, Delwin McLaughlin and Robert Walton, as well as Drs. Scott and Selina Heppell from Oregon State University. REEF Volunteers have always been at the core of our Grouper Moon field work and 2010 was no exception – heartfelt thanks to Heather George, Steve Gittings, Denise Mizell and Sheryl Shea. The support and assistance of Thor Dunmire is also greatly appreciated. The Grouper Moon Project has continued through the years empowered by the first year’s success and the passion of early project leader Leslie Whaylen Clift. Assistance from OSU graduate student, Stephanie Kraft Archer, is much appreciated. Principal financial support is from the Lenfest Ocean Program of the Pew Charitable Trusts and the CIDOE. Additional funding is from Mr. Wayne Panton, Mr. Dan Scott, Clive and Stella Wood, Franklin and Cassandra Neal, and hundreds of REEF members. Continued in-kind logistical support from island businesses and residents, including the Little Cayman Beach Resort/Reef Divers, the Southern Cross Club, Peter Hillenbrand, Dottie Benjamin, and Judie Clee is also much appreciated. To alleviate the constraints of diving deep depths on regular scuba, several other sponsors came on board to assist in the project, including Divetech and PM Gas of Grand Cayman, Silent Diving of Brockville, Ontario and Shearwater Research of Vancouver, British Columbia.

And finally, our work on Grand Cayman would not have been possible without the generous support of Wayne Sullivan, who donated his vessel the Glen Ellen, his time (and patience), his equipment and technical diving expertise, and his crew, Brady Booton and several others.

For more information on the project, visit the Grouper Moon Project Webpage. If you would like to support this critical marine conservation research, please donate today through the REEF Website or call REEF HQ at 305-852-0030.

Design by Joanne Kidd, development by Ben Weintraub