Processing 4-D acoustic data from the worlds most advanced multi-beam fisheries sonar
Acoustic methods are widely used for estimating fish abundance. Institute of Marine Research (IMR) uses data from echo sounder to calculate abundance of many fish species. Vertical echo sounders does not cover the region close to the sea-surface, and is therefore not suited to investigations at those times the fish swim close to the surface.
The move towards investigation of complete ecosystems force simultaneous investigations of many species, i.e. also when fish are too close to the sea-surface to be investigated with echo sounders. IMR specified requirements to a quantitative multi-beam SONAR to be used in combination with the echo sounder as recent development of technology has made it possible to make both such a SONAR and a system to post process its data. Currently the most advanced multi-beam SONAR of the world can deliver calibrated output to be used for abundance estimation of fish. Potentials of such SONARs are discussed, and simple applications are demonstrated.