This map series shows the vessel transit counts or relative density of large commercial cargo, tanker, tug-tow, passenger, fishing, recreation, other, or all vessels in 2011-2013 and 2015-2022. These maps are based on data received from Automatic Identification Systems (AIS). Maps generally show the annual vessel activity; for select years and vessel types, maps also show monthly activity.
Not all vessels are equipped with AIS, nor are all vessels required to carry and operate an AIS. AIS utilizes radio frequency transmissions, and therefore the effective range at which a vessel can be detected can vary widely based on atmospheric conditions and equipment configuration. For these maps, vessel tracks were derived from raw AIS data provided by the U.S. Coast Guard. The vessel tracklines were used to generate transit counts or density values to convey patterns of vessel activity by vessel type.
The datasets may contain errors in vessel categorization. For example, some vessel operators did not report their vessel type or reported the wrong category by mistake, and some vessels are used for multiple purposes but are included in only one AIS category (e.g., a boat categorized as a pleasure craft that also operates as a fishing vessel). In addition, while every effort is made to ensure data quality, occasional errors can occur in processing these data.
All data are final and will be updated as described in the 2016 Northeast Ocean Plan.
Support for Regional Ocean Planning
For information about how these data and maps were developed with stakeholder input, and how they will be used to support regional ocean planning, please see the 2016 Northeast Ocean Plan at www.neoceanplanning.org.