Layer: _Tier 2 Bottom Type ______________________________________________________
Source: _Brian Conrad (DMF)__NC One Map_________________________________________
File Name: _ebhm.zip___________________________________________________________
Abstract: The need for extensive shellfish management in North Carolina has been recognized
since the 1947 North Carolina General Assembly authorized the Division of Commercial
Fisheries to conduct a rehabilitation program to restore the declining oyster (Crassostrea
virginica) fishery. More recently, rising prices and increased demand for hard clams (Mercenaria
mercenaria) and Bay Scallops have spurred the implementation of new management
techniques and philosophies toward this expanding fishery. Although the Fisheries
Management Section of the N.C. Division of Marine Fisheries has been actively managing these
shellfish resources since 1964, it has done so with limited resource base information. The most
complete and accurate shellfish bottom survey in North Carolina waters was done by Lt. Francis
Winslow, U.S. Navy, in 1889 and was limited to the larger estuaries. This survey was targeted
solely toward oysters and potential oyster producing grounds, and although it was quite
extensive in Pamlico Sound, it has long since become outdated. Beginning in 1978, the Division
of Marine Fisheries has undertaken a shellfish bottom survey of the commercial shellfishproducing waters in the coastal area. The purpose of the survey is to locate and map shellfishproducing areas and to delineate potentially productive benthic shellfish habitats. Gross
determinations of shellfish concentrations within productive bottom types are to be
determined through a stratified random sampling program. The information generated from
this survey is expected to update resource base data to a level from which information can be
drawn for making management decisions. A preliminary survey of the Newport River system
was conducted from November 1980 to April 1981. Newport River was selected as a testing
ground for survey techniques because of its close proximity to sampling headquarters, its
diverse fisheries and environmental characteristics, and the pressing need for resource base
data in such a dynamic system. From this survey it was deemed that the mapping techniques
and survey methods proved acceptable, and in 1987 the estuarine waters were divided into
areas based on shellfish habitat suitability criteria. In 1989 the Shellfish Resource Mapping
Proposal was introduced, which led to the creation of the Shellfish Mapping Program in 1990
MSA I2 is the second iteration of Shellfish Bottom Mapping. I2 is developed based on newer
shoreline created from high resolution imagery. There are changes in mapping process with use
of updated transect grid size (6" * 6") and also use of mapping grade GPS for ground truthing
purposes. Iteration 2 (I2) data should be used when it is geographically available.
Purpose: GOAL - To survey, evaluate and map North Carolina's shellfish habitat to provide a
more comprehensive fisheries management scheme. OBJECTIVES - 1) To summarize existing
shellfish information and evaluate shellfish producing habitat based on environmental and
utilization criteria. 2) To survey shellfish habitats to obtain baseline data and production
potential information. 3) To define and delineate existing and potential shellfish habitat
through a series of resource maps. 4) To provide for better utilization of estuarine resources
through improved information for management and increased public awareness.
Supplemental Information: Process from Survey to GIS Data Developement: Base maps of each
area were created by use of ESRI ARCGIS software, using shapefiles of USGS 24K quad maps and
shellfish area boundary polygons. A one-minute and a ten-second latitude/longitude grid layers
were placed on the area coverage. One-minute latitude/longitude lines were labeled for
geographic reference. Mapping of strata was accomplished through the use of various size
small outboard vessels and a crew of at least two individuals. One person navigates the survey
vessel on the ten second transects using a DGPS unit, while the other person uses sounding
poles of various lengths to probe the benthic habitat. The person using the sounding poles calls
out the strata type as it is found, and the person navigating records the strata type on the field
map at that particular latitude and longitude on the field map. In areas where there are
apparent changes in strata between the ten second lines, five second lines or less are
transected until the strata type boundaries are identified. Field map data consisting of strata
types and boundaries is then transferred to an office map by use of a light table. After which,
the paper office map is digitally scanned using a Widesystem Contex scanner. Data is scanned
at a high resolution as a color image. The image is then georeferenced using Georeferencing
tools in ESRI ArcGIS. MSA coverage, 1-min and 10-sec grids are used in the process for
Georeferencing the image to their true coordinates. At least 4 control points are used and a low
RMS error is achieved before registering the image. Line work is digitized in ESRI Personal
Geodatabase Feature Class and converted into polygon data. Later the data is checked for
topology errors. Attributes, including acreage, are calculated and added as required. Individual
area coverages are then verified by the Shellfish Mapping Biologist/Supervisor; once verified
these areas are merged into the final MSA database.
Distribution Liability: NCCGIA is charged with the development and maintenance of NC
OneMap and, in cooperation with other mapping organizations, is committed to offering its
users accurate, useful, and current information. Although every effort has been made to ensure
the accuracy of information, errors and conditions originating from physical sources used to
develop this dataset may be reflected in the data supplied. The user must be aware of possible
conditions and bear responsibility for the appropriate use of the information with respect to
possible errors, original map scale, collection methodology, currency of data, and other
conditions specific to certain data. NCCGIA does not support secondary distribution of this
dataset without its current, compliant metadata record. The use of trade names or commercial
products does not constitute their endorsement by NCCGIA or North Carolina State
Government. Although every effort has been made to ensure the accuracy of information,
errors and conditions originating from physical sources used to develop the corporate database
may be reflected in the data supplied. The user must be aware of data conditions and bear
responsibility for the appropriate use of the information with respect to possible errors, original
map scale, collection methodology, currency of data, and other conditions specific to certain
data. North Carolina Division of Marine Fisheries does not support secondary distribution of this
data. The use of trade names or commercial products does not constitute their endorsement by
the Division of Marine Fisheries or North Carolina State Government.
Metadata: The user must read and fully comprehend the metadata prior to data use.
Acknowledgement of products derived from this data set should cite the following: The source
of the dataset is the North Carolina Division of Marine Fisheries. Earlier versions of this data
set may exist. The user must be sure to use the appropriate data set for the time period of
interest. While efforts have been made to ensure that these data are accurate and reliable
within the state of the art, NCDMF cannot assume liability for any damages or
misrepresentation caused by any inaccuracies in the data or as a result of changes to the data
caused by system transfers.
Publication Date: 20101021
Originator: NC Division of Marine Fisheries
Publisher: North Carolina Division of Marine Fisheries
Online Linkage: http://portal.ncdenr.org/web/mf
Time Period of Content:
Time Period Information:
Single Date/Time:
Calendar Date: 1989-Current
Currentness Reference: bottom condition
Status:
Progress: In work
Maintenance and Update Frequency: As needed
Spatial Domain:
Bounding Coordinates:
West Bounding Coordinate: -78.574269
East Bounding Coordinate: -75.450108
North Bounding Coordinate: 36.018056
South Bounding Coordinate: 33.804217
Contact Electronic Mail Address: brian.conrad@ncmail.net
Contact Voice Telephone: 252-726-7021
Grid Coordinate System Name: State Plane Coordinate System 1983
Horizontal Datum Name: North American Datum of 1983
Planar Distance Units: meters
Ellipsoid Name: Geodetic Reference System 1980