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The Designated Shellfish Growing Area (DSGA) datalayer was compiled by the Department of Fish and Game's (DFG) Division of Marine Fisheries (DMF). Three hundred and three growing areas in Massachusetts have been designated by DMF's Shellfish Project.
A designated shellfish growing area is an area of potential shellfish habitat, and all three hundred and three DSGA's make up the territorial waters (tidal zone out to the territorial line) of the Commonwealth. Growing areas are managed with respect to shellfish harvest for direct human consumption, and comprise at least one or more classification areas. The classification areas are the management units, and range from being approved to prohibited (six different classification types in all) with respect to shellfish harvest. For example, one growing area may be composed of four classification areas, all of which are managed separately (have a classification type the same or different from the rest in the growing area). This layer reflects classification areas as of September 30, 2009.
In ArcSDE the DSGA data are stored in a polygon feature class named DSGA_POLY.
The growing areas and their classification areas were defined by DMF shellfish project biologists. Compilation base maps covering the entire coast and islands were plotted at 1:5,000 using 1:5,000 Color Ortho Imagery and 1:24,000 USGS Topographic maps, all modified and enhanced by MassGIS. In addition, town boundaries, the territorial waters line and roads were plotted on these base maps. Shellfish project biologists compiled area boundaries onto the base maps, and these boundaries were then digitized or constructed using existing hydrography, town or territorial sea lines by DMF GIS personnel. Check plots were created and boundaries QA/QC'd by the biologists.
Separate 11 x 17 color plots are produced for each growing area based on the mapextent of the area and its sampling stations. Classification area lines which need to be added, moved or deleted are compiled on these plots and automated by DMF GIS staff. A new 11 x 17 is produced and kept on file until another area change occurs.
The polygon attribute table has the following attributes associated with each polygon:
NAME Classification area name (Code format similar to GROWING_AR. Starts with GROWING_AR and is appended by a ‘.' and a number making it unique within the growing area. For example: N2 has a classification area in it called N2.0 TYPE Classification type or how classification area is classified with respect to shellfish harvest for direct human consumption. There are six classification types which are listed below. STATUS Classification status or whether the area is OPEN or CLOSED to shellfish harvest for direct human consumption. CONTACT Name of shellfish biologist responsible for the area ACRES Acreage of classification area BEGIN_DATE Date classification area was classified. GROWING_AR Code name for growing area. For example: N2 is the GROWING_AR for the Merrimack River COND Area condition (classification) type. COND_DETAI Area classification details (if any) AREA_DESC Well-known (common) name for each classification area. LGL_DESC Classification area legal description GRW_DESC_ID Numeric identifier for polygons with the same GROWING_AR
Note, symbol numbers have been included because the Division of Marine Fisheries Shellfish Project has asked that the same shadeset symbols are used for each classification type so that maps are plotted consistently.
The GRW_DESC_ID field links to IDs in several different tables in an Oracle relational database. Information in the database is extensive and covers the area names and classification types, legal boundary descriptions, date of classification, rainfall data and acreage figures. Historical information about each area is maintained, beginning January 1, 1995. In addition, area information is also associated with water quality and marine biotoxin sampling data collected by shellfish project biologists, used to manage the areas. A separate GIS datalayer called Shellfish Sampling Stations has been created to maintain the sampling points.
APPROVED Open for harvest of shellfish for direct human consumption subject to local rules and state regulations. CONDITIONALLY
During the time area is approved it is open for harvest of shellfish for direct human consumption subject to local rules and state regulations. CONDITIONALLY
During the time area is restricted it is only open for the harvest of shellfish with depuration subject to local rules and state regulations.
RESTRICTED Open for harvest of shellfish with depuration subject to local rules and state regulations or for the relay of shellfish. MANAGEMENT
Closed for harvest of shellfish. Not enough testing has been done in the area to determine whether it is fit for shellfish harvest or not. PROHIBITED Closed for harvest of shellfish.
The Division of Marine Fisheries and MassGIS are maintaining this datalayer. With the October 2009 update the lines feature class DSGA_ARC was dropped. Also see Shellfish Suitability Areas datalayer description.
Last Updated 10/8/2009