Albemarle-Pamlico Sounds
Shellfish Strata Survey
Type: Extent
of habitat (i.e., area of habitat and whether there has been a decline)
and condition of habitat and sources affecting habitat (i.e.,
the condition or functionality of the habitat).
Category: Intertidal
Cost: Information not provided.
Description: The North Carolina Department of Environment
and Natural Resources, Division of Marine Fisheries, in cooperation
with the NC Center for Geographic Information and Analysis, developed
a GIS Shellfish Strata data set to enhance planning, siting and
impact analysis in areas directly affecting the underwater habitat
of different shellfish species, including oysters, clams and scallops
in North Carolina.
To delineate shellfish habitat, a series of transects were established
that ran latitudinally at maximum intervals of one-tenth of a minute
(510 feet). While traversing a given transect, the bottom of the
sound was probed with a metal pipe to determine substrate type.
These soundings were estimated to be a maximum distance apart of
100 feet. For each transect the beginning and ending point was sounded
and location (latitude and longitude) and bottom type was recorded.
This bottom sounding method was the principal means for establishing
strata. From interpretations of the transect data, the strata boundaries
were drawn onto USGS 1:24,000-scale topographic maps. Three types
of sampling gear were used to conduct the survey:
1. Quadrant sample-a square measure constructed of PVC pipe used
on exposed strata in the intertidal region.
2. Patent tongs-two rake-like appendages with teeth that operate
opposite each other in scissors-like fashion and when closed form
a basket. The tongs are opened, closed, positioned, lowered and
raised hydraulically using the outboard motor of the boat as a power
source.
3. Dredge-a steel frame device with a "mouth" approximately two
feet wide and one foot high with an attached net that is dragged
along the bottom by a boat.
The NC DENR-DMF delineated the boundaries on mylar overlays of shell-fish
strata mapped 1:12,000 scale.
Outcome: A polygon coverage depicting the presence of underwater
habitat of different shellfish, including oysters, clams, and scallops,
as determined by the NC Division of Marine Fisheries. The polygon
attribute table (PAT) has attribute data including total area in
coverage units (square meters), total perimeter (linear meters),
polygon internal identification number, polygon user identification
number, and an item representing the shellfish species. Hydrographic
feature names are annotated.
Contact: NC DENR-Division of Marine Fisheries, c/o Liz Noble,
Marine Fisheries Biologist, 3441 Arendell Street, Morehead City,
NC 28557, (919) 726-7021 (voice), (919) 726-9218 (FAX)
Citation: http://www.cgia.state.nc.us/cgdb/ss12f.html
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