Accession Number : ADA304214

Title :   Model Estimates of Acoustic Scattering from Schools of Large Yellowfin Tuna.

Descriptive Note : Final rept.,

Corporate Author : NAVAL RESEARCH LAB STENNIS SPACE CENTER MS

Personal Author(s) : Nero, Redwood W.

PDF Url : ADA304214

Report Date : 05 JAN 1996

Pagination or Media Count : 23

Abstract : Acoustic scattering models for fish schools are used to predict scattering from large yellowfin tuna at frequencies of 50 Hz to 200 kHz. Fish of 80- to 130-cm fork length were modeled in schools of 300 to 1400 individuals. At high frequency, 2 to 200 kHz, school target strength was 0.9 to 2.5 dB. At low frequency, 50 to 1000 Hz, school target strength at resonance was highly variable, ranging from 2 to 18 dB. Just above and below resonance, scattering was complex with target strength variations of 40 dB or more caused by changes in several parameters describing school size, fish size, school depth, and packing density. At high frequency, scattering from schools of other species may be confused with tuna schools. Recommendations are made to use broadband systems at either low and high frequency in order to successfully identify tuna and to discriminate them from other fish. Additional experiments are recommended to verify model results.

Descriptors :   *RESONANCE SCATTERING, *TARGET DISCRIMINATION, *COMMERCIAL FISHING, *ACOUSTIC SCATTERING, *TUNA, SIZES(DIMENSIONS), VARIATIONS, RESONANCE, BROADBAND, PACKING DENSITY, TARGET STRENGTH, ACOUSTIC RESONANCE.

Subject Categories : Acoustics
      Biological Oceanography

Distribution Statement : APPROVED FOR PUBLIC RELEASE