A new multibeam echo sounder/sonar for fishery research applications

Abstract

Fisheries scientists have for many years been requesting a calibrated multibeam echo sounder/sonar specially designed for fishery research applications. Simrad AS has, in cooperation with IFREMER, France, agreed on specifications for a multibeam echo sounder and with IMR, Norway for a multibeam sonar, and contracts were signed for development of such systems in January 2003. The systems have 800 transmitting and receiving channels with similar hardware, but different software, and are characterized by narrow beams, low-sidelobe levels, and operate in the frequency range 70–120 kHz. The echo sounder is designed for high operating flexibility, with 1 to 47 beams of approximately 2°, covering a maximum sector of 60°. In addition, normal split beam mode on 70 and 120 kHz with 7° beams for comparison with standard system is available. The sonar will be mounted on a drop keel, looking horizontally, covering a horizontal sector of ±30°, and a vertical sector of 45°. Total number of beams is 500, 25 beams horizontally with a resolution of ∼3°, and 20 beams vertically with a resolution of ∼4°. Both systems are designed for accurate fish-stock assessment and fish-behavior studies.

Adaptation of fisheries sonar for monitoring schools of large pelagic fish: dependence of schooling behaviour on fish finding efficiency

“…The validation of sonar settings also requires additional experiments at sea, if the abilities of sonar detection are to be optimized. Accurate sonar technology is now operational (Andersen et al 2006); this technology however needs large vessels, and can not be used autonomously at the present time. New pulse form in hyperbolic frequency modulation, introduce on modern fisheries sonar (Simrad 2007), should provide a better accuracy of school definition (vs. continuous wave pulse form).…”