Shellfish Areas in the Gulf of
go to: USFWS Gulf of Maine Watershed Habitat Analysis
Various species of bivalve shellfish (mussels, clams, scallops, etc.) are important food items for waterfowl and seabirds, and therefore are of interest when mapping habitats for those birds. We assembled data characterizing shellfish beds within the Gulf of Maine study area, then scored or classified those areas according to the resolution of the data. Areas mapped at lower resolution or characterized in a more generic manner were scored "5" while areas mapped from more extensive surveys at a finer resolution were scored "10". These numbers reflect our relative confidence that shellfish would actually be found at a given location during a site inspection.
The most general source was the NOAA National Shellfish Register coverages, the 1995 National Shellfish Register of Classified Growing Waters (Geographic Coverages), obtained from http://seaserver.nos.noaa.gov/projects/95register/.
These are approximately 1:70,000 scale coverages, indicating among other polygon attributes, the relative abundance for a large range of species. Within the study area 7 species are relatively important: Softshell Clams (Mya arenaria), Hard Clams (Mercenaria mercenaria), Surf Clams (Spisula solidissima), Ocean Quahog Clams (Arctica islandica), Eastern Oysters (Crassostrea virginica), Mussels (Mytilidae spp.), Bay Scallops (Argopecten irradians) and Sea Scallops (Placopecten magellanieus).
We combined the individual state coverages, selecting polygons in which any of these species was characterized as "moderate" or "high abundance"
We selected grids of shellfish beds from a previous analysis of Great Bay, New Hampshire (Banner and Hayes 1996). We combined polygons containing clam, mussel, and oyster beds, and used this to replace the more general NOAA data for this area. Similarly, a data set from Maine Department of Marine Resources with polygons representing commercially valuable concentrations of bivalve shellfish in Maine was used to replace those NOAA data. Finally, a coverage from Maine Geological Survey, the Coastal Marine Geologic Environments, was used to supplement information on mussel bars.
Shellfish areas from the Great Bay and Maine data sets were scored 10, and the NOAA data was scored 5 in a final raster (grid) coverage, indicating the relative probability of finding shellfish at the mapped locations.
Banner, A. and G. Hayes. 1996. Important Habitats of Coastal New Hampshire. Falmouth Maine: U.S. Fish and Wildlife Service Gulf of Maine Project. 77pp.