BROADBAND ACOUSTIC CLASSIFICATION OF INDIVIDUAL ZOOPLANKTON AND FISH: A REVIEW OF RECENT WORK

Le résumé fourni par la source

Echoes resulting from broadband insonification of marine life such as zooplanktan and fish are rich with information.The challenge lies in developing an optimal approach toward extracting meaningful biological informationfrorn the data.Because ofthe complexity of the acoustic scattering by the organisms, we have studied the scattering through a combination of theoretical modeling and extensive laboratory measurements of broadband acoustic scattering by a variety of live individual animals.Speci cally, we have recorded echoesfram three major anatomical groups of zooplankton: 1) fluid-like (shrimp and euphausiids), 2) elastic shelled (pteropods and (benthic) periwinkles), and 3) gas-bearing (siphanophores), as well as a bladder bearing fish species (alewife).The frequencies were continuously distributed over about an octave of bandwidth: 350 -650 kHz for the zooplankton and 40 100 kHz for the fish.Some of the animals were rotated over all angles of orientation in one or two planes and in one-degree steps.The echoes were examined in both the frequency and time domains.In the time domain, pulse-compression processing was applied in order to resolve individual features of the animals.The data were classified using both physics-based and statistics-based algorithms.Size, gross anatomical group, and sometimes orientation information could be inferredfrom the data.

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