These data have been derived from Massachusetts Division of Marine Fisheries (DMF) fishermen catch reports, Standard Atlantic Fisheries Information System (SAFIS) dealer transaction reports, and National Marine Fisheries Service (NMFS) vessel trip reports. The raw reported data refer to either DMF Statistical Reporting Areas, DMF Designated Shellfish Growing Areas, or Latitude/Longitude point coordinates. The amount of fishing effort (# fishing trips / year / sq km) from all sources were combined and converted to a 250 x 250-meter raster grid. Likewise, the landings value (# fishing trips / year / sq km) per area were calculated and converted to an identical grid. To prevent the scale of commercial fisheries in one part of the state overshadowing the importance of those in other parts of the state, the planning area was broken into 2 regions: north of Cape Cod and south of Cape Cod. These two grids were re-classified into 10-percentile bins within each of those regions, so as to place them on the same scale. They were then combined with equal weight and reclassified into the top 25% (value = 4), middle 50% (value = 3) and bottom 25% (value = 2) of the data.
To allow for consistent evaluation and comparison of a variety of datasets with distinct spatial resolutions, accuracies, and other characteristics, the Massachusetts ocean management planning area was partitioned into 250 x 250-meter grid cells, each with a unique ID. These data were converted to the planning area grid by extracting all of the cells in which the data layer occurred.