On acoustic multi-frequency species identification and separation of Atlantic mackerel, Norwegian spring spawn herring and Norway pout.

Abstract

The accuracy of the multi-frequency species identification and separation algorithms may be significantly improved when the detailed acoustic scattering characteristics of the fish are known, including its expected variability and uncertainty. The modeling approach is effective for interpreting measured data collected for different fish species and may give a better understanding of the acoustic scattering characteristics. The paper is motivated by development of algorithms of multi-frequency species identification and separation of three economically valuable North European fish species: Atlantic mackerel, Norwegian spring spawn herring and Norway pout. The backscattering by these fish is studied using an advanced modeling approach, and the results of the analysis are compared with selected multi-frequency recordings. This allows for an explanation of the main backscattering mechanisms over the selected frequency range and often a better understanding of the dominating acoustic scattering parameters. The impact of fish orientation behavior, pressure (for herring) and the morphological state of the fish is also discussed. Typical backscattering frequency responses for herring, mackerel and Norway pout are explained theoretically. The obtained results may be a base for improving the automatic identification algorithms now introduced in scientific echo sounder post-processing systems.