2023_programme: Pulse length effects on Bluefin tuna's TS measurements in the near range

• Session: 09. New frontiers in fisheries acoustics: applications- analysis- decision and management tools
  Organiser(s): Victor Espinosa
• Lecture: Pulse length effects on Bluefin tuna's TS measurements in the near range [invited]
  Paper ID: 2044
  Author(s): Ladino-Velasquez Anderson, Pérez-Arjona Isabel, Morillo-Faro Andrés, Puig-Pons Vicent, Espinosa Víctor
  Presenter: Espinosa Victor
  Abstract: We have studied, both numerical and experimentally, the influence of pulse duration on target strength (TS) measurements of Bluefin tuna (Thunnus thynnus). A methodology for simulating the real temporal pulse of an echo sounder using the meshless numerical simulation of fundamental solutions (MFS) method is proposed. Decomposition of the spectral components to reproduce the original pulse emitted by the different pulse durations of the echo sounder and the corresponding echo for TS evaluation has been carried out. The calculations were carried out with calibration spheres and a real 3D Bluefin tuna swim bladder shape from a computerized tomography (CT). Experimental measurements were taken at working frequencies of 120kHz and 200kHz using split-beam scientific echosounders (Simrad Ek60 and Ek80). Five pulse durations have been evaluated (64, 128, 256, 512, and 1024 μs). The results validate the use of all pulse lengths to estimate the TS at short distances without causing considerable deviations in the TS values, being the most important source of TS dispersion the near field effect of fish as a scatterer.
• Corresponding author: Prof Victor Espinosa
  Affiliation: Universitat Politècnica de València
  Country: Spain
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