Gray's Reef National Marine Sanctuary
Gray's Reef National Marine Sanctuary
Gray's Reef Expedition 2012
Mission Information

Fish Censuses

Gray's Reef National Marine Sanctuary (GRNMS) is located 16 miles offshore of Sapelo Island, Georgia, and protects 22 square miles of rocky carbonate-cemented sandstone reefs. These rocky reefs consist of ledges that can be as tall as six feet and provide shelter for a diverse community of invertebrates, algae, and fishes.

Seaweed blenny

Seaweed blenny
(Photo: Greg McFall, GRNMS)

NOAA established a research area in Gray's Reef to increase the opportunity to scientifically discriminate between natural ecological changes within the sanctuary versus changes caused by humans.

Diver with quadrat

Diver with quadrat
(Photo: Katalin Zakara, ONMS)

One goal of the research area is to determine the effect of bottom fishing on benthic (associated with the ocean bottom) fish populations. This year scientists aboard the NOAA Ship Nancy Foster, will continue the collection of annual data by conducting benthic habitat and fish community surveys at numerous sites located within and outside the research area.

Quadrats are a PVC frame of a known unit of area (such as 0.25 m2) which are used to identify and photograph invertebrate organisms present on the bottom. We will also census the large, colorful, (conspicuous) fishes such as groupers and snappers together with the small, juvenile, and often times subdued-colored (cryptic) fishes such as blennies and wrasses that can serve as important prey for larger fishes. These fish communities will be censused by swimming along a ledge for a known unit of length and width (a 25 m transect that is 4 m wide) and counting, identifying, and estimating the sizes of all fishes seen within the transect.


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