OVERVIEW

The Designated Shellfish Growing Area (DSGA) datalayer was compiled by the Department of Fisheries, Wildlife and Environmental Law Enforcement's (DFWELE) 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 July 1, 2000.

In ArcSDE the DSGA data are stored in two feature classes - DSGA_POLY and DSGA_ARC.

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 1:12,000 using hydrography from 1:24,000 USGS DLG; 1:100,000 USGS DLG; and 1:25,000 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:
 

GRW_AREAID		ID associated to each growing area
CL_DESC_ID		Unique ID foreach class area
GRW_AREACD		Code name for growing area.  For example: N2 is the GRW_AREACD for the Merrimack River
GRW_AREA_NM		Meaningful name for growing area (For example: Merrimack River for N2)
CL_AREANM		Classificationarea name (Code format similar to GRW_AREACD.  Starts with GRW_AREACDand 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
CL_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.
CL_STATUS		Classification status or whether the area is OPEN or CLOSED to shellfish harvest for direct human consumption.
CL_BEGINDT		Date classification area was classified.

CLASSIFICATION TYPES:
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.

APPROVED		Open for harvest of shellfish for direct human consumption subject to local rules and state regulations. (SHADESET SWPI - SYMBOL 3)
CONDITIONALLY APPROVED		During the time area is approved it is open for harvest of shellfish for direct human consumption subject to local rules and state regulations. (SHADESET SWPI-SYMBOL 502)
CONDITIONALLY RESTRICTED		During the time area is restricted it is only open for the harvest of shellfish with depuration subject to local rules and state regulations. (SHADESET SWPI- SYMBOL 265)
RESTRICTED		Open for harvest of shellfish with depuration subject to local rules and state regulations or for the relay of shellfish. (SHADESET SWPI - SYMBOL381)
MANAGEMENT CLOSURE		Closed for harvest of shellfish. Not enough testing has been done in the area to determine whether it is fit for shellfish harvestor not. (SHADESET SWPI- SYMBOL 34)
PROHIBITED		Closed for harvest of shellfish. (SHADESET SWPI - SYMBOL 2)

The two ID's (GRW_AREAID and CL_DESC_ID) link to ID's 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 SHLFSHST has been created to maintain the sampling points; see the Shellfish Sampling Station Datalayer description for details.

The layer's arc attribute table has the following attributes associated with each arc (same as 1:25K hydrography, since coastline was constructed using this datalayer):

 MINOR_TOT
 SOURCE
 COAST
 MINOR_NUM

See the 1:25,000 Hydrography Datalayer description for codes.

The attribute SOURCE has also been used to code added arcs (non-hydrography arcs) as part of lines between adjacent growing areas and classification areas as well as overall polygon closure lines.  The codes are as follows:
 

SOURCE = C		Indicates an arc which separates two classification areas within the same growing area.
SOURCE = G		Indicates an arc which separates two growing areas.

These codes can be useful when plotting, as the arcs can be identified and plotted differently.

The Division of Marine Fisheries and MassGIS are maintaining this datalayer. Also see Shellfish Suitability Areas datalayer description.

Last Updated 1/14/2008
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