Over the last decade, West African coastal countries, including Ghana, have experienced extensive economic damage due to illegal, unreported and unregulated (IUU) fishing activity, estimated at about USD 100 million in losses each year. Illegal, unreported and unregulated fishing poses an enormous threat to the conservation and management of the dwindling fish stocks, causing multiple adverse consequences for fisheries, coastal and marine ecosystems and for the people who depend on these resources. The Integrated System for Surveillance of Illegal, Unlicensed and Unreported Fishing (INSURE) is an efficient and inexpensive system that has been developed for the monitoring of IUU fishing in Ghanaian waters. It makes use of fast-delivery Earth observation data from the synthetic aperture radar instrument on Sentinel-1 and the Multi Spectral Imager on Sentinel-2, detecting objects that differ markedly from their immediate background using a constant false alarm rate test. Detections are matched to, and verified by, Automatic Identification System (AIS) data, which provide the location and dimensions of ships that are legally operating in the region. Matched and unmatched data are then displayed on a web portal for use by coastal management authorities in Ghana. The system has a detection success rate of 91% for AIS-registered vessels, and a fast throughput, processing and delivering information within 2 h of acquiring the satellite overpass. However, over the 17-month analysis period, 75% of SAR detections have no equivalent in the AIS record, suggesting significant unregulated marine activity, including vessels potentially involved in IUU. The INSURE system demonstrated its efficiency in Ghana’s exclusive economic zone and it can be extended to the neighbouring states in the Gulf of Guinea, or other geographical regions that need to improve fisheries surveillance.

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Detection of vessels from space-based synthetic aperture radar (SAR) data is an important area of research with many applications, including fisheries monitoring, counter-piracy, and maritime border security. The detection of vessels on the ocean surface in SAR imagery requires that the vessel has sufficiently high radar cross section (RCS). In general, the RCS of an object is a function of the object's material, size, and shape, as well as RADAR parameters such as center frequency. Even, two objects of the same size may have different RCSs based on construction materials (i.e., wood versus metal). In Ghana, as in much of the Gulf of Guinea, wooden canoes 6-25 m in length represent a significant percentage of maritime traffic. These canoes are not easy to detect and track in coastal RADAR, nor are they easily detected in SAR imagery. These vessels may represent a significant risk to maritime safety and security. Here, we describe one possible solution for the problem described-above based on inexpensive, versatile corner reflectors with high RCS. Specifically, we describe the design and construction of high RCS corner reflectors and results from a series of experiments in which corner reflectors were installed on wooden canoes. During the experiments, canoes were deployed to specific locations off the coast of Ghana at specific times, corresponding to the acquisition of space-based SAR imagery. We present results from these experiments, which indicate that wooden canoes with these corner reflectors can be detected in space-based SAR imagery.Index Terms-Maritime domain awareness, small vessel detection, synthetic aperture radar (SAR).

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