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Integrating Mapping and Fisheries Data for Deep-Sea Coral Habitats off South Carolina and Georgia

Project Goal

To analyze multibeam sonar data in order to map sites off of South Carolina and Georgia and determine if they contain habitat such as coral and rugged bottom topography that are the preferred habitats of snapper, grouper and other economically valuable species.

Geographic Location

South Atlantic Bight, off South Carolina and Georgia

Approach

Raw bathymetric and backscatter data were compiled for selected shelf-edge and slope hard-bottom reefs in the region. Detailed seafloor maps and habitat characterizations were made using a modification of Battista’s (2007) methods. Multibeam bathymetric data were cleaned and processed, or existing data and backscatter data were extracted using CARIS and QPS Fledermaus software. Metrics of bottom complexity (depth, slope, rugosity, etc.) were calculated and compared to the original bathymetric data to estimate validity of boundaries of bottom types. Fishery survey data were compared to seafloor images.

Results

Three primary depth ranges were studied: (1) the 50-meter ridge along the shelf edge; (2) 200-meter depths adjacent to the shelf edge; and (3) deeper areas along the Charleston Bump. The 50-meter ridge represents a discontinuous to continuous rocky outcrop with 1-10 meters of relief along the shelf edge. High rugosity provides substantial habitat for corals and fishes. The 200-meter scour zone represents a sandy to silty section with abundant iceberg scours providing a broken surface for high-rugosity habitat. Smooth areas are typically silty to sandy with rock pavement in places. The "Georgetown Hole" reef off Georgetown, South Carolina covers the range from approximately 160-meter to over 230-meter depths, and exemplifies the complexities in this upper-slope area. The Charleston Bump surveys in 400-meter to 600-meter depths documented the well-known high-relief coral and fish habitat scoured by the Gulf Stream.

Importance to Management

The products generated through this project will support management actions by providing habitat data to place-based fishery management and biodiversity conservation. They will provide information to evaluate mapped sites as potential Essential Fish Habitat (EFH) and Habitat Areas of Particular Concern (HAPC) off South Carolina and Georgia, and to provide methodologies for more rapid assessment of areas during future data gathering expeditions. Additionally, these maps will support the management goals of the South Atlantic Fishery Management Council, by informing where permitted fishing areas can be designated within the newly created deep-sea coral HAPC off the southeast, that minimize impacts on corals.

Links

Efforts being conducted regionally by partners at the College of Charleston are demonstrated at the Project Oceanica seafloor mapping web site:  http://oceanica.cofc.edu/SeaMap/default.htm.

Fiscal Year 2009 Funding

$15,000

Point of Contact

George R. Sedberry, George.Sedberry@noaa.gov

Sites mapped and analyzed in the current project. The image shows bathymetry and rough bottom along the shelf-edge reef and Charleston Bump, and fish trap locations in the fishery-independent database (green triangles).

Credit: Scott Harris, College of Charleston and NOAA