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Broadband Discrimination Between Anatomical Groups of Fish and Zooplankton--Demersal and Pelagic Regions

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January 1, 2006 through December 31, 2006

Dr. Timothy Stanton
Woods Hole Oceanographic Institution, Woods Hole, MA 02543

Program Manager: Michael Jech NOAA/NMFS

Related NOAA Strategic Plan Goal:
Goal 1. Protect, restore and manage the use of coastal and ocean resources through ecosystem-based management.

Project Overview
The purpose of the research is to address the limitations of traditional high frequency acoustic systems by using a novel broadband acoustic system spanning most of the frequency range, 1-100 kHz. The lower portion of this frequency range fills in the crucial “gap” missed by high frequency systems so that the difference in scattering characteristics between fish with swimbladders, fish without swimbladders, and large zooplankton can be determined unambiguously. In this one-year study, data recently collected in the Georges Bank and Gulf of Maine regions with the FR/V Delaware II are analyzed. The analysis is focussed on studying the frequency dependence of the acoustic scattering by organisms of different anatomical groups.

Two major anatomical groups were observed-- Atlantic Herring (swimbladder-bearing) and various macrozooplankton (no gas inclusion). The difference in scattering characteristics is striking (Figs. 1, 2). In the case of the swimbladder-bearing fish, there was a strong resonance at approximately 3.7 kHz, above which the scattering level drops. In the case of the zooplankton, the scattering was of negligible strength at that frequency and increased rapidly with frequency until leveling off at frequencies above about 80 kHz. The acoustic signatures of these two different types of organisms are irrefutably different. These data provide a basis for discriminating organisms belonging to different anatomical groups with significantly reduced ambiguity over existing high frequency acoustics methods.

One conference proceedings describing the above is in print and a journal article is in preparation.

Stanton, T.K, Chu, D., Jech, J.M., and Irish, J.D. (2007), “A broadband echosounder for resonance classification of swimbladder-bearing fish,” Proceedings of the 2007 IEEE Oceans Conference in Aberdeen, Scotland.

Summary of Interaction with NOAA
These data were collected on the FR/V Delaware II on leg 1 of the 2005 herring cruise, sponsored by NOAA. The research was in collaboration with Dr. Mike Jech of NOAA.

Last updated: August 19, 2008

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