NOAA/NCCOS Point Shapefile - 100m2 Fish Density for Tortugas Ecological Reserve and Riley's Hump, United States, 2011, WGS84

The research mission was conducted in the Dry Tortugas, FL by National Ocean Service scientists from the Center for Coastal Habitat and Fisheries Research (CCFHR) during 2011 aboard the NOAA Ship Nancy Foster. The overall objective of CCFHR's research in the Tortugas is to examine the effects of implementation of the Tortugas North Ecological Reserve (TNER). The establishment of the TNER, a no-take reserve, in 2001 provided the opportunity to examine the response of the fish and benthic communities to the creation of a refuge for exploited reef fishes. Historically, exploitation of reef fishes in the Tortugas has focused on large predatory reef fishes, primarily snappers and groupers and, to a lesser extent, grunts. Trends in populations of these targeted species are expected to vary relative to geographic variation in fishing mortality (F). Increasing trends in targeted species abundance are expected in the TNER where all fishing was prohibited in 2001. Within adjacent areas managed as the Exclusive Economic Zone (EEZ), where both federally sanctioned commercial and recreational fisheries are permitted, exploited populations are expected to be depressed relative to those in the TNER. Within the Dry Tortugas National Park (DTNP) where fishing effort is limited to recreational hook and line fishing, trends in exploited species are expected to be intermediate to those observed in the TNER and EEZ. Cascading effects due to change in abundance of exploited species is expected to indirectly impact corals and other sessile benthic communities. Sampling to detect reserve implementation effects was conducted at the ecotone between the reef habitat of the banks and the surrounding soft-bottom shelf where the structure and composition of communities should provide sensitive indicators of a reserve effect. Energy flow across reef-sand boundaries is critical to reef communities. Energy and nutrients are imported to the reef by nocturnally foraging reef fish that feed in sand, algae, and seagrass flats adjacent to the reef. The majority of the TNER (approximately 70%) consists of soft-bottom shelf habitat, and previous work on the west Florida shelf suggests that benthic primary production is the major energy source supporting fish biomass. In addition to providing ecologically sensitive sampling locations, the interface between bank and shelf provided a distinct landscape feature suited to a comparative analysis of management impact. Observations were made using 1) a stratified-random survey design for scuba divers visual observations, 2) a systematic survey of fish and fauna using scientific splitbeam echosounders (fisheries sonar) to map fish densities and biomass on the shelf, coral and softbottom habitats.

1. To design and implement a mobile fisheries sonar survey in concert with multibeam echosounder hydrographic surveys to assess and map fish densities and biomass within and outside management zones.2. To assess distribution of fish densities relative to management and ecological reserve boundaries and other differences that may be associated with management zones and habitat types, particularly as fish distributions relate to movements between habitat types.3. To assess the extent of fish density distributions in comparison with diver visual surveys and fish community assessments.

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ESRI ArcGIS 10.1

These data consist of fish densitys in the Dry Tortugas Florida Keys National Marine Sanctuary. The data was collected during corresponding multibeam operations.

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