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Shellfish (Hardclam, softclam, oysters)

Frequently-asked questions:


What does this data set describe?

Title:
Shellfish (Hardclam, softclam, oysters)

Abstract:
Shellfish polygons were digitized from hand drawn polygons representing hardclam, softclam, and oyster beds produced by the Department of Agriculture from their records in 1990 (approximately).

The data is general in its nature and should be used only as a guide.

  1. How should this data set be cited?

    State of Connecticut, Department of Environmental Protection (data compiler, editor and publisher), 1997, Shellfish (Hardclam, softclam, oysters).

    Online links:
  2. What geographic area does the data set cover?

    Bounding coordinates:
    West: -73.664651
    East: -71.850638
    North: 41.357323
    South: 40.968899

  3. What does it look like?

  4. Does the data set describe conditions during a particular time period?

    Calendar date: 1990
    Currentness reference:
    ground condition

  5. What is the general form of this data set?

    Geospatial data presentation form: vector digital data

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      This is a Vector data set. It contains the following vector data types (SDTS terminology):
      • G-polygon (424)

    2. What coordinate system is used to represent geographic features?

      The map projection used is Lambert Conformal Conic.

      Projection parameters:
      Lambert Conformal Conic
      Standard parallel: 41.200000
      Standard parallel: 41.866667
      Longitude of central meridian: -72.750000
      Latitude of projection origin: 40.833333
      False easting: 999999.999996
      False northing: 499999.999998

      Planar coordinates are encoded using coordinate pair.
      Abscissae (x-coordinates) are specified to the nearest 0.000250.
      Ordinates (y-coordinates) are specified to the nearest 0.000250.
      Planar coordinates are specified in survey feet.

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222.

      Vertical coordinate system definition:
      Altitude system definition:
      Altitude resolution: 1.000000
      Altitude encoding method: Explicit elevation coordinate included with horizontal coordinates

  7. How does the data set describe geographic features?

    depgis.DEP.SHELLFISH
    ACREAGE
    Calculated area of polygon feature in acres. Note, ACREAGE values are not automatically updated after modifying feature geometry (shape). Values must be recalculated after features are edited, simplified, generalized, clipped, dissolved, etc. (Source: State of Connecticut, Department of Environmental Protection)
                      

    Shape
    Feature geometry. (Source: ESRI)
                      

    Coordinates defining the features.

    SHELLFISH
    Text field indicating the presence of one or more types of shellfish data resulting from the aggregation of hardclam, softclam, and oyster data. (Source: State of Connecticut, Department of Environmental Protection)
                      

    OYSTER
    True/False indicator on whether the oyster layer indluded values for the gien area. (Source: State of Connecticut, Department of Environmental Protection)
                      

    HARDCLAM
    True/False indicator on whether the hardclam layer included values for the given area. (Source: State of Connecticut, Department of Environmental Protection)
                      

    Sequential unique whole numbers that are automatically generated.

    OBJECTID
    Internal feature number. (Source: ESRI)
                      

    Sequential unique whole numbers that are automatically generated.

    SHAPE
    Feature geometry. (Source: ESRI)
                      

    Coordinates defining the features.

    SHAPE.area
    SOFTCLAM
    True/False indicator on whether the sofclam layer included values for the given area. (Source: State of Connecticut, Department of Environmental Protection)
                      

    SHAPE.len
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Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)


  2. Who also contributed to the data set?

  3. To whom should users address questions about the data?

    State of Connecticut, Department of Environmental Protection
    79 Elm St.
    Hartford, CT 06106-5127
    USA

    860-424-3540 (voice)
    860-424-3540 (FAX)
    860-424-3540
    Hours of Service: Monday to Friday, 08:30 to 16:30 Eastern Standard Time
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Why was the data set created?

The Shellfish layer is 1:24,000-scale data. It depicts the approximate location of shellfish beds along the Connecticut coast and is suitable as a general means of identifying a resource area.  This layer should not be construed to depict the actual, absolute locations of any shellfishing resources.  Use this layer with other 1:24,000-scale map data such as the Coastal Boundary, Town Boundaries, Roads and Trails, Airports, Railroads and other base map data derived from the USGS 7.5 minute topographic quadrangle maps and compiled at a 1:24000 scale.

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How was the data set created?

  1. Where did the data come from?

    Source 1 - CT Dept of Agriculture Shellfish maps (source 1 of 3)

    Source 2: Hardclam, softclam, and oyster GIS shapefiles (source 2 of 3)

    Source 3 - Shellfish Layer (source 3 of 3)

  2. What changes have been made?

    Date: 1990 (change 1 of 2)
    Hard clam, soft clam, and oyster bed polygons were digitized from hand drawn polygons produced by the Department of Agriculture from their records in 1990 (approximately).
    
    

    Data sources used in this process:
    • Source 1 - CT Dept of Agriculture Shellfish maps

    Data sources produced in this process:
    • Source 2: Hardclam, softclam, and oyster GIS shapefiles

    The individual hardclam, softclam, and  oyster GIS shapefiles were aggregated into one shellfish layer.  Attributes were modified to describe whether an area was comprised of one or several types of shellfish classes.

    Data sources used in this process:
    • Source 2: Hardclam, softclam, and oyster GIS shapefiles

    Data sources produced in this process:
    • Source 3 - Shellfish Layer

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How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

    The layer retains the feature types and information identified by the State of Connecticut, Department of Environmental Protection and obtained from the Department of Agriculture hardclam, softclam, and oyster maps. All attributes have valid values. Values are within defined domains. 

  2. How accurate are the geographic locations?

    The horizontal positional accuracy of this data is unknown. The polygon features represent approximate positions for arge area objects or observations. 

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    The completeness of the data reflects the feature content of the data sources, which include the Department of Agriculture source maps.. The layer is complete in the sense that it accurately reflects the contents of the source information available at the time the State of Connecticut, Department of Environmental Protection created the layer. However, compared to current conditions, the layer may be incomplete. This data is not updated.

  5. How consistent are the relationships among the observations, including topology?

    Establishment of logical consistency was performed by the State of Connecticut, Department of Environmental Protection using ESRI ArcGIS software to manually create and control feature topology in SHAPEFILE format. No automated procedures or tests were performed to guarantee desired topology other than visual inspection.

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How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access constraints: None. The data is in the public domain and may be redistributed.
Use constraints:
There are no legal prerequisites for using the data, however this layer should not be construed to depict the actual, absolute locations of any shellfishing resources.  Note, the data is not intended for maps printed at map scales greater or more detailed than 1:24,000 scale (1 inch = 2,000 feet.)  Once acquired, any modification made to the data must be noted in the metadata. When printing this information on a map or using it in a software application, analysis, or report, please acknowledge the State of Connecticut, Department of Environmental Protection as the source for this information.

Distributor 1 of 1

  1. Who distributes the data set?

    State of Connecticut, Department of Enviromental Protection
    79 Elm St.
    Hartford, CT 06106-5127
    USA

    860-424-3034 (voice)
    860-424-4054 (FAX)
    dep.gisdata@ct.gov
    Hours of Service: Monday to Friday, 08:30 to 16:30 Eastern Standard Time

  2. What's the catalog number I need to order this data set?

    Downloadable DEP Shellfish Data.

  3. What legal disclaimers am I supposed to read?

  4. How can I download or order the data?

    • Availability in digital form:


    • Data format:
      Size: 0.854
      Network links:http://www.ct.gov/deep

    • Cost to order the data: An online copy of the data may be accessed without charge.


  5. Is there some other way to get the data?

    Geographic information sytem (GIS), computer-aided drawing or other mapping software is necessary to display, view and access the information. 
    

  6. What hardware or software do I need in order to use the data set?

    Geographic information sytem (GIS), computer-aided drawing or other mapping software is necessary to display, view and access the information.

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Who wrote the metadata?

Dates:
Last modified: 20120119

Metadata author:
Kevin O'Brien
State of Connecticut, Department of Environmental Protection
79 Elm St.
Hartford, CT 06106-5127
USA

860-424-3034 (voice)
860-424-4054 (FAX)
dep.gisdata@ct.gov
Hours of Service: Monday to Friday, 08:30 to 16:30 Eastern Standard Time

Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata(FGDC-STD-001-1998)

Metadata extensions used:
  • http://www.esri.com/metadata/esriprof80.html

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