This map broadly characterizes mackerel commercial fishing vessel activity in the Northeast based on Vessel Monitoring System (VMS) data in 2014 at vessel speeds less than 4 knots. The National Marine Fisheries Service (NMFS) designated specific mackerel codes within the new Squid/Mackerel/Butterfish fishery plan starting in 2014, resulting in smaller temporal coverage for this product. The relative amount of vessel activity is indicated qualitatively from high (red) to low (blue). NMFS describes VMS as “a satellite surveillance system primarily used to monitor the location and movement of commercial fishing vessels in the U.S.” The map is intended to show fishing activity (excluding vessel transit at higher speeds) by showing VMS data records below 4 knots, a speed cutoff between fishing and transit suggested by industry members and managers during project meetings. The most accurate interpretation of this map is that it indicates relative levels of vessel presence at speeds associated with fishing activity.

Data Considerations

The data provided by NMFS contained the day/month/year, the geographic coordinates of the vessel at the time of transmission, speed over ground, and the vessel’s declaration code, which may signify fishery plan, program within that plan, and associated area identifier or gear-type information. These data then were aggregated by combining all program codes within each fishery plan.

The limitations of the data used to produce these maps should be understood prior to interpretation of this map.

These data are from vessels operating in certain fishery management plans and certain programs within those plans. This map displays data for vessels using VMS with a mackerel limited access permit (50 CFR 648.10).

It is important to note that these data include all trips using a Mackerel VMS code by vessels with these permits, and as such, may include trips that target other fisheries but use a Mackerel VMS declaration for another fishery as a management and reporting mechanism. There are many New England fisheries not described through any VMS-derived maps.

VMS data are subject to strict confidentiality restrictions. Therefore, the map shows the density of vessel locations following the removal of individually identifiable vessel positions. The process of removing sensitive vessel locations followed the “rule of three” mandated by NMFS Office of Law Enforcement (OLE) by using a screening grid to identify which grid cells contained three or more VMS records. VMS records within cells that contain fewer than three VMS records were not included in the analysis. A statistical method to normalize data was used on the subsequent density grids and data values represent standard deviations. While legends are consistent across products, values represent high or low areas of vessel activity specific to each dataset. Detailed information on processing techniques is outlined in the metadata.


These data were updated and posted on Northeast Ocean Data in fall 2015, and they will continue to 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 will be used to support regional ocean planning, please see the 2016 Northeast Ocean Plan at www.neoceanplanning.org.

1 In general, vessels holding permits in certain fisheries are required to use VMS. See www.greateratlantic.fisheries.noaa.gov/vms/regs/index.html for additional information, including a link to federal regulations describing requirements for the use of VMS. Fisheries with vessels required to use VMS include: full-time or part-time limited access scallop; limited access monkfish/occasional scallop or combination permit electing to provide VMS notifications; limited access multispecies (groundfish; e.g., cod, flounder species, haddock, pollock, plaice, halibut, redfish, ocean pout, hake) permit when fishing on a category A or B day at sea (DAS); surfclam or ocean quahog open access permit; Maine mahogany quahog limited access permit; limited access monkfish vessel electing to fish in the Offshore Fishery Program; limited access herring permit; limited access squid permit; limited access mackerel permit.