Use of marine protected areas (MPAs) to preserve habitat for marine vertebrates has become an important tool for conservation managers. One of 14 MPAs that make up the US National Marine Sanctuary System, the Florida Keys National Marine Sanctuary (FKNM S), was designated on 16 November 1990 in response to a series of ship groundings in 1989, as well as mounting threats from coral disease and declining water quality. The sanctuary covers 2,900 square nautical miles of waters surrounding the Florida Keys and protects the third largest coral barrier reef ecosystem in the world, including more than 6,000 species of marine life, as well as cultural resources. To assess the use of habitats within FKNMS by marine turtles, we satellite-tracked 126 turtles including threatened loggerheads (Caretta caretta), endangered green turtles (Chelonia mydas), and endangered hawksbills (Eretmochelys imbricata) from 2008-present. All turtles were tagged in either Dry Tortugas National Park (DRTO) or Everglades National Park (ENP). We filtered tracking data and plotted all turtle tracking days within and adjacent to FKNMS boundaries, in 5x5 km grid cells.
In over 35,000 turtle tracking days, we determined “hotspot” grid cells (# of tracking days > 200) where turtle tracking days were concentrated during both breeding (April-August) and non-breeding (September-March) seasons. Multispecies hotspots were located both inside (60%) and outside (40%) of currently designated national wildlife refuges, FNKNMS, and national park boundary lines. Several important hotspots also serve as year-round habitat for adult marine turtles, including DRTO and the Key West National Wildlife Refuge. This unique geospatial dataset provides managers with a new, almost real-time marine spatial planning tool, as currently proposed sanctuary protection areas and other areas of human use may be evaluated against turtle distribution across the seascape.