Census Information

Census 2004

2004

In the summer of 2004 a team of researchers led by Jerry Ault, University of Miami’s Rosenstiel School of Marine and Atmospheric Science (UM/RSMAS), surveyed reef fish populations in an area covering nearly 450 square nautical miles in the Dry Tortugas region of the Florida Keys. The Tortugas region contains: the Tortugas Ecological Reserve-North (Florida Keys National Marine Sanctuary); the adjacent southern section of the Tortugas Bank that remains open to commercial and recreational fishing (Bank fishable); and, Dry Tortugas National Park, where commercial fishing has been banned since 1960. The Tortugas Ecological Reserve (Bank MPA — marine protected area), which covers over 150 square nautical miles, is the largest “no-take” marine zone in U.S. waters. In addition to UM/RSMAS, the team included scientists from NOAA Fisheries, National Park Service, Florida Fish and Wildlife Conservation Commission, NOVA Southeastern University, and the University of North Carolina at Wilmington/National Undersea Research Center. In 20 operational days the 43-member team conducted 1,594 scientific dives for 37.5 days underwater where they mapped nine types of benthic habitats and recorded the abundance and size of about 275 fish species.

Results of the survey showed that pinnacle and reef terrace habitats had the highest diversity of fish species and that the Tortugas reserve and national park had higher fish diversities than the fished section of the Tortugas Bank. The survey recorded greater abundances of red and black grouper than had been counted in 1999 and 2000, prior to implementation of the ecological reserve in 2001; black grouper abundance had increased four- to five-fold over previous surveys in the same areas. The marine protected areas should not get sole credit for this upsurge in black grouper populations because of an increase in its legal minimum-catch size in 1999. Survey data analysis indicates that “the system is moving in the right direction,” given these increases in diversity and abundance of reef fishes. Population increases in heavily exploited reef fishes and spiny lobster have also been measured in the rest of the network of fully protected marine zones in the Florida Keys National Marine Sanctuary, implemented in 1997. These efforts are a critical step towards understanding the efficacy of such actions in meeting resource management goals.

Please click here for a complete report of the 2004 Dry Tortugas Expedition.