Feasibility of time-dependent amplitude in pulse-compressed broadband acoustic signals for determining the dorsal orientation of fish

0583815 - BC 2024 RIV CH eng J - Journal Article
Tušer, Michal - Brabec, Marek - Balk, H. - Draštík, Vladislav - Kubečka, Jan - Frouzová, Jaroslava
Feasibility of time-dependent amplitude in pulse-compressed broadband acoustic signals for determining the dorsal orientation of fish.
Water. Roč. 15, č. 8 (2023), č. článku 1596. E-ISSN 2073-4441
R&D Projects: GA MŠMT(CZ) EF16_025/0007417; GA MŠMT(CZ) EF16_013/0001782
Institutional support: RVO:60077344 ; RVO:67985807
Keywords : backscattering * swimbladder * dorsal aspect * tilt angle * matched-filter processing
OECD category: Marine biology, freshwater biology, limnology; Statistics and probability (UIVT-O)
Impact factor: 3.4, year: 2022
Method of publishing: Open access
https://doi.org/10.3390/w15081596

Fish body orientation significantly influences the size obtained with hydroacoustic signals, and thus the estimate of fish size and biomass. For this reason, each characteristic of a target's echo can be advantageous for developing algorithms to refine acoustic fish estimates. We measured pulse-compressed broadband acoustic signals from tethered fish (common bream Abramis brama) in different dorsal positions. Based on generalized additive mixed models (GAMM), we initially tested the influence of the fish dorsal aspect on the amplitude echo envelope and amplitude echo descriptors (amplitude maximum and amplitude echo length at seven different levels below the maximum) by altering the fish dorsal orientation. Our study confirmed that the dorsal aspect influenced the shapes of the amplitude echo envelopes in both fast- and slow-tapered pulses. Furthermore, we found that echo lengths approximately 15 dB below the amplitude maximum, especially for fast-tapered signals, could provide good characteristics of the echo-envelope shape for determining the fish dorsal aspect and facilitating thus the conversion between acoustic target strength and true fish length.
Permanent Link: https://hdl.handle.net/11104/0351813