1.2 Available Data

The GFW AIS dataset includes three main types of information about vessels: attributes (such as length, tonnage, flag, and gear type), positions (in WGS84), and activities (like encounters, loitering, port visits, and fishing). Data are available from 2012 - present. AIS coverage has increased overtime and is generally considered good from 2016 onward. Most of the tables with vessel information are related through the source specific vessel id (ssvid). For AIS data, the ssvid corresponds to the vessel’s Maritime Mobile Service Identity (MMSI).

Country VMS datasets provide reliable vessel tracking with low risks of tampering or transmission gaps since VMS devices generally broadcast at fixed rates and many countries impose strict requirements on VMS use with hefty fines for violations. When available, VMS data can complement AIS data, particularly in regions where AIS reception is poor, allowing for a greater understanding of fishing activity. Years of available data and level of metadata for VMS varies by country and approval to use the data is almost always required. A description and date range for the various country VMS datasets is provided on the GFW VMS Wiki page. If you are interested in using VMS data in your research please reach out to Tyler Clavelle at GFW.

The SAR detections data are from around October, 2014 - present and are updated intermittently. Imagery availability increases along the data acquisition timeframe, especially from mid-2016 on. However, SAR detections only cover nearshore regions and most offshore areas do not have any detection data. VIIRS data is available from 2016 - present and is updated periodically.