Use of Sentinel-l and Sentinel-2 for Monitoring Illegal Fishing Off Ghana

Abstract

An efficient and inexpensive service has been developed for the monitoring of fishing vessels in West Africa using Earth Observation (EO) data. The service makes use of fast- delivery data from the Synthetic Aperture Radar (SAR) instrument on Sentinel-1 and the Multi Spectral Imager (MSI) on Sentinel-2, detecting objects that differ markedly from their immediate background using a constant false alarm rate (CFAR) test. The selected objects are then discounted from further analysis if they fall within the bespoke land mask or can be shown from time series analysis to be static (signals associated with jetties, oil platforms and "ghost objects" arising from very bright land targets). Detections are matched to, and verified by, AIS data, which provides location and dimensions of ships that are legally in the region. Both matched and un-matched data are then displayed on a web portal for use by the Gulf of Guinea (GoG) state authorities.