Multi-frequency backscattering from the sea floor; can the frequency response be used to identify typical sandeel grounds?
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In this report a phenomenological characterization technique of received bottom echoes has been developed and studied, to evaluate the potential of locating typical sandeel grounds. Data from a calibrated multi--frequency echosounder collected during a Survey Methods for Abundance Estimation of Sandeel (Ammodytes marinus) Stocks (SMASSC) survey in the sandeel fishing grounds of "Vestbanken" and "Elbow Spit North", were processed with developed scripts in Matlab to extract first received bottom echo parameters. Together with Simrad SEABEC results and sandeel samples, possible distinctive parameters were found for what could be sandeel grounds. However, ambiguities caused by ping to ping fluctuations and complex behavior of the sandeel species make the characterization difficult. Many of the calculated echo parameters showed possible discrimination power for a future multi-variate analysis.