Integrating spaceborne SAR imagery into operational systems for fisheries monitoring

• Published in: Canadian journal of remote sensing 2001-08, Vol.27 (4), p.291-305
• Main Authors: KOURTI, N, SHEPHERD, I, SCHWARTZ, G, PAVLAKIS, P
• Format: Article
• Language: English
• Subjects: Applied geophysics; Earth sciences; Earth, ocean, space; Exact sciences and technology; Fishing boats; Internal geophysics; Marine; Marine geology; Remote sensing systems; Tracking equipment
• ISSN: 0703-8992; 1712-7971
• DOI: 10.1080/07038992.2001.10854872

The European Commission is investigating the feasibility of integrating SAR imagery as a tool for fisheries monitoring. The detectability and identification of fishing vessels subject to VMS (Vessel Monitoring System), i.e., vessels longer than 24m, has been proven by comparing detected vessel positions with VMS position reports from the Flemish Cap, the North Sea and the Azores area. In this first area, fishing vessels dominate the maritime traffic, in the second, there is significant marine traffic connected to the oil extraction. While VMS gives a good idea of all the vessels using VMS, SAR imagery provides a passive way to understand activity in an area for those vessels not using their VMS or not being subject to it, or whose VMS is not working. RADARSAT ScanSAR imagery is the most suitable beam mode, as it covers a wide area and its resolution is sufficient to allow detection of vessels subject to VMS. The work carried out in this first part of the study has shown that there is good agreement between detected vessel positions from spaceborne SAR imagery and VMS position reports, when the latter are produced frequently enough, i.e., every hour or shorter. Hence it would be feasible for inspectors to correlate the two information sources and derive information about vessels not using or not subject to VMS. The surveillance and control could then concentrate on those boats only. Image-processing time is an important issue as vessels are not stationary targets. In Europe there are only two ground stations for RADARSAT imagery. The one of West Freugh is the only one that covers the southern European Waters. Still the eastern Mediterranean remains uncovered and the image has to spend significant time on board the satellite before it can be downloaded. Thus it loses its added value for fisheries control. Our studies on image fast processing have revealed that most of the time of the whole process, about one hour and 50 minutes, is spent at the West Freugh ground station. Transferring the image to a site where the ship detection can be carried out may take five to ten minutes, in case of a dedicated transfer link, or from 20 minutes to four hours in the case where the standard Internet route is taken. The actual detection does not take more than three minutes on a PC with a Pentium III processor at 600MHz with 512MB RAM. This implies that detection results can be available to the inspectors already two hours after the image recording. The coverage problem is