Marine Protected Areas (MPAs) are considered an important tool by scientists and conservationists for increasing marine biodiversity and helping the recovery of depleted fisheries. Many fishermen seem to tacitly agree: by focusing their effort along the boundaries of these protected areas -- also known as "fishing the line" -- they prove that fishing is better in the seas around these protected areas.

SkyTruth analyzed a time-series of three radar images acquired during a one-year period by the RADARSAT satellite over the MPA known as Closed Area 1 on Georges Bank, off Cape Cod. Radar is extremely effective at detecting and monitoring fishing vessels and other ships at sea. Ship locations were identified on the images, then compiled in a Geographic Information Systems (GIS) database.

The results are shown here, plotted on a backdrop image that is a composite of bathymetry (shown in color) and a standard Landsat satellite image of Cape Cod. Vessel locations are plotted in color corresponding to the date of each radar image. Fishing-the-line behavior is strongly suggested by the clusters of vessels just outside the closed area boundary. Several vessels were also detected within the protected area. These may simply be ships in transit, or they could indicate violations of the fishing closure.

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