Hard Clam - Shrewsbury River () [New Jersey] {1983}
New Jersey Department of Environmental Protection's (NJDEP) Bureau of GIS · 1983 Full Details
Full Details
- Title
- Hard Clam - Shrewsbury River () [New Jersey] {1983}
- Description
- The Inventory of New Jersey's The Inventory of New Jersey's Estuarine Shellfish Resources is conducted on a rotating basis throughout the major Atlantic coastal estuaries of New Jersey. The primary purpose of the work is to estimate the standing stock of hard clams (Mercenaria mercenaria) and describe their relative distribution. Additionally, the survey describes the relative distribution of other commercially important bivalve species and vascular submerged aquatic vegetation ("SAV"), also known as seagrasses. Hard Clam: The substrate is sampled with a hydraulic hard clam dredge designed to retain clams sized 30mm and larger. All live clams collected are counted and measured to the nearest millimeter. The density of clams at each station is reported in clams per square foot. The resulting geospatial data represents the relative distribution of hard clams at either "none" (no clams collected), "low" (0.01 to 2), "moderate" (>0.20 - 2), or "high" (>0.50 clams/ft2) densities. Where no category designation is given, the area is considered a "no data" area relative to this survey. This means that the survey did not sample within this area for reasons including shallow water, obstructions, or the presence of shellfish aquaculture leases. The area may or may not be marked formally as such. However, a "no data" area may contain shellfish resources unknown to the Marine Resources Administration (MRA) or the MRA may have data for the area from other investigations. It does not automatically mean that the area is devoid of shellfish resources. This data represents a one point in time documentation of relative abundance of hard clams, and hard clams may be found presently in areas not previously sampled or at stations where they were not historically collected. Complete reports for each surveyed estuary provide methodology, analysis, charts, and additional pertinent information, and can be found on the NJ Fish and Wildlife's website. The NJ Coastal Zone Management rules at N.J.A.C. 7:7 define shellfish densities of 0.2 clams per square foot or greater as productive shellfish habitat. The Leasing of Atlantic Coast Bottom for Aquaculture regulations discourages establishing leases in productive shellfish habitat (NJAC 7:25-24.6(d)). Note that this layer does not include delineation of shellfish leases or aquaculture development zones. Those data are provided separately. Data from 1980s were digitized based primarily on the georeferenced images of the 1980s' map series, in combination with usage of the 1986 NJDEP Landuse/Landcover geospatial dataset to more accurately depict shoreline boundaries. Digitizing was completed using freehand and/or copying/pasting/editing waterbody features from the 1986 NJDEP Landuse/Landcover geospatial dataset. Digitizing was completed at a scale between 1:4,000 to 1:12,000. This data represents a digital interpretation of the original hard copy charts. Therefore, some anomalies may exist in the line features along the present-day coastline. Users should interpret the mapping to extend to the present-day coastline. Data from 2000s to present were created based upon survey station tabular data which was then mapped as a point feature class. Several GIS tools were then used to generate polygon features surrounding the stations to represent hard clam distribution (see Process Steps for more detail). Associated Species: When other commercially or recreationally important bivalve species are retained in the sample, they are documented, along with common invertebrate species. Data from the 1980s documents the presence of all other commercially and recreationally important bivalve species that are regulated by the State of New Jersey as well as common (but not all) shellfish predators that were retrained in the dredge while targeting hard clams. Presence indicates the area is productive for the species. The regulated bivalve species are soft clams (Mya arenaria), bay scallops (Argopecten irradians), surf clam (Spisula solidissima), Eastern oyster (Crassostrea virginica), and blue mussel (Mytilus edulis). This data is a point in time observation of production areas and regulated bivalve species may be found presently in areas not previously sampled or at stations where they were not historically collected. This data represents a digital interpretation of the original hard copy charts. Therefore, some anomalies may exist in the line features along the present-day coastline. Users should interpret the mapping to extend to the present-day coastline. It is important to note that this data is not a comprehensive evaluation of Eastern oyster populations in the Mullica River, Great Egg Harbor River, or Delaware Bay, which are surveyed separately and specifically for that species. Similarly, although surf clams are occasionally found in estuarine environments, the species primarily dwells in the Atlantic Ocean and separate comprehensive population surveys of state and federal waters are available. For additional species collected (for example sponges, non-commercial shellfish, etc.) please contact the Bureau of Shellfisheries. Historical reports for each surveyed estuary provide methodology, analysis, charts, and additional pertinent information, and can be requested by contacting the Marine Resources Administration. The features were digitized based primarily on the georeferenced images of the 1980s' map series, in combination with usage of the 1986 NJDEP Land use/Landcover geospatial dataset in order to more accurately depict shoreline boundaries. Digitizing was completed using freehand and/or copying/pasting/editing waterbody features from the 1986 NJDEP Landuse/Landcover geospatial dataset. Digitizing was completed at a scale between 1:4,000 to 1:12,000. This data represents a digital interpretation of the original hard copy charts. Therefore, some anomalies may exist in the line features along the present-day coastline. Users should interpret the mapping to extend to the present-day coastline. Data from 2000 to present also documents the presence of all other commercially and recreationally important bivalve species that are regulated by the State of New Jersey as well as common invertebrates, including common bivalve predators. Presence indicates that area is productive for the species listed. The regulated bivalve species are soft clams (Mya arenaria), bay scallops (Argopecten irradians), surf clam (Spisula solidissima), Eastern oyster (Crassostrea virginica), and blue mussel (Mytilus edulis). This data is a one point in time observation of production areas and regulated bivalve species may be found presently in areas not previously sampled or at stations where they were not historically collected. It is important to note that this data is not a comprehensive evaluation of Eastern oyster populations in the Mullica River, Great Egg Harbor River, or Delaware Bay, which are surveyed separately and specifically for that species. Similarly, although surf clams are occasionally found in estuarine environments, the species primarily dwells in the Atlantic Ocean and separate comprehensive population surveys of state and federal waters are available. Further, data on channeled whelk (Busycotypus canaliculatus), knobbed whelk (Busycon carica), Atlantic horseshoe crab (Limulus polyphemus) and blue crab (Callinectes sapidus) are not intended for use in fishery management plans at this time. For additional species collected (for example sponges, non-commercial shellfish, etc.) please contact the Marine Resources Administration. This feature class was created based upon survey station tabular data which was then mapped as a point feature class. Several GIS tools were then used to generate polygon features surrounding the stations to represent each species' distribution (see Process Steps for more detail). Submerged Aquatic Vegetation: When submerged aquatic vegetation (SAV; seagrass) is retained in the sample, or observed visually from the research vessel, the presence of the vegetation and species is noted. Only presence of the vegetation is provided, without inference regarding coverage, shoot density, or any other characteristic. Only regulated species (per N.J.A.C. 7:7-9.6) of vascular vegetation is presented here. This is primarily eelgrass (Zostera marina) and widgeon grass (Ruppia maritima. However, other regulated species are found in New Jersey. Data from 1980s is a "snapshot in time" of relative distribution of SAV, and SAV may be found presently in areas not previously sampled or at stations where they were not historically collected. Species composition may change over time. This data represents a digital interpretation of the original hard copy charts. Therefore, some anomalies may exist in the line features along the present-day coastline. Users should interpret the mapping to extend to the present-day coastline. Where hard copy charts were not previously created (Shrewsbury, Manasquan, and Metedeconk Rivers), a 1,000ft buffer was placed around the survey station where SAV was found. Historical reports for each surveyed estuary provide methodology, analysis, charts, and additional pertinent information, and can be requested by contacting the Marine Resources Administration. The SAV data from the 1980s can confirm the history of SAV in a given area, corroborating other survey years. However, further investigation is necessary if it is the only dataset available for a project. In such cases, please contact the Marine Resources Administration (MRA) as they may have information on the area that was collected during different surveys or is not yet published. Data from 2000s to present is also a "one point in time" documentation of relative distribution of SAV, and SAV may be found presently in areas not previously sampled or at stations where they were not historically collected. Species composition may change over time. Where SAV was found, a 1,000ft buffer was placed around the survey station. Complete reports for each surveyed estuary provide methodology, analysis, charts, and additional pertinent information, and can be found on the NJ Fish and Wildlife website. This feature class was created based upon survey station tabular data which was then mapped as a point feature class. Several GIS tools were then used to generate polygon features surrounding the stations to represent hard clam, associated species, and SAV distribution (see Process Steps for more detail).
- Creator
- New Jersey Department of Environmental Protection (NJDEP), Fish and Wildlife (FW), Office of Fish and Wildlife Information Systems
- Publisher
- New Jersey Department of Environmental Protection's (NJDEP) Bureau of GIS
- Temporal Coverage
- 1983
- Date Issued
- 2023-12-05
- Access Rights
- Public
- Format
- Shapefile
- Language
- English
- Date Added
- August 28, 2025
Location
Download
Links
Cite and Reference
-
Citation
New Jersey Department of Environmental Protection (NJDEP), Fish and Wildlife (FW), Office of Fish and Wildlife Information Systems (2023). Hard Clam - Shrewsbury River () [New Jersey] {1983}. New Jersey Department of Environmental Protection's (NJDEP) Bureau of GIS. https://gisdata-njdep.opendata.arcgis.com/datasets/njdep::hard-clam-shrewsbury-river-1983 (web service) -
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