Adaption of the M3 multi-beam sonar to fisheries a

Abstract

Monitoring and quantification of estuarine and shallow water coastal resources where sub-surface development, such as in-stream tidal power and aquaculture, occurs will require specialized and portable acoustic technologies. The newly released M3 sonar combines the high refresh rate of a conventional multibeam image quality comparable to single beam sonar thereby enabling the high resolution detection of water column targets and structures. Data collect during 2011 demonstrates that the 500kHz system is capable of collecting fine scale acoustic data at ranges up to 100m, the isolation of individual targets from fish schools, and may potentially function as a split beam multibeam system with the phase extraction capability. The latter will provide a mechanism to position targets in 3D within a beam (120o swath) and greatly simplify system calibrations. In addition, the sonar's sensitivity can be adjusted to match the frequency of some commercial acoustic tags (200kHz and greater) and the interference used to detect tagged fish with a bearing at ranges up to 400 m or more. This paper summarizes the results of field studies on the detection of fish and targets, the detection ranges of acoustic tags, and looks at a broad range of applications and recommendations for future development.