The Bergen multifrequency analyzer (BMA): A new toolbox for acoustic categorization and species identification

Multifrequency split‐beam echo sounders with nearly identical and overlapping acoustic beams have been regularly used in acoustic surveys for fish stock abundance estimation. Calibrated raw data from up to six simultaneously working echo sounders at 18, 38, 70, 120, 200, and 364 kHz were applied for developing a new processing tool for real‐time acoustic target categorization and acoustic species identification. The system now handles raw data from the Simrad EK500 and EK60 split‐beam echo sounders, and performs a stepwise, modular sequence of analysis, like bottom detection, noise quantification and removal, target categorization, and school detection in near‐real time. Direct generation of new, synthetic echograms, based upon the measured frequency response of the targets, is also one of the most useful features of the system. This information may significantly increase the accuracy of acoustic survey estimates of fish and zooplankton. New routines for noise removal, target categorization, and school de...