Estimation of target strength of Sardina pilchardus and Sardinella aurita by theoretical approach

Ayoubi, Salaheddine El; Mamza, Kamal; Fujino, Tadanori; Abe, Kouji; Amakasu, Kazuo; Miyashita, Kazushi

doi:10.1007/s12562-016-0986-8

Cited by 3 publications

(2 citation statements)

References 25 publications

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“…Low and high acoustic trophic level classes were assumed to represent plankton (i.e., meso and macrozooplankton) vs. pelagic fish, respectively. Usually, small pelagic fishes occurring in the CCLME have a S v , higher than ~ − 68 dB 79 , while macrozooplankton backscatter at < − 70 dB 16,80 . Low, high, and total acoustic trophic levels were, thus, designated as plankton (PG), pelagic fish group (PFG), and total group (TG), respectively.…”

Section: Methodsmentioning

confidence: 99%

On the robustness of an eastern boundary upwelling ecosystem exposed to multiple stressors

Diogoul

Brehmer

Demarcq

et al. 2021

Sci Rep

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The resistance of an east border upwelling system was investigated using relative index of marine pelagic biomass estimates under a changing environment spanning 20-years in the strongly exploited southern Canary Current Large marine Ecosystem (sCCLME). We divided the sCCLME in two parts (north and south of Cap Blanc), based on oceanographic regimes. We delineated two size-based groups (“plankton” and “pelagic fish”) corresponding to lower and higher trophic levels, respectively. Over the 20-year period, all spatial remote sensing environmental variables increased significantly, except in the area south of Cap Blanc where sea surface Chlorophyll-a concentrations declined and the upwelling favorable wind was stable. Relative index of marine pelagic abundance was higher in the south area compared to the north area of Cap Blanc. No significant latitudinal shift to the mass center was detected, regardless of trophic level. Relative pelagic abundance did not change, suggesting sCCLME pelagic organisms were able to adapt to changing environmental conditions. Despite strong annual variability and the presence of major stressors (overfishing, climate change), the marine pelagic ressources, mainly fish and plankton remained relatively stable over the two decades, advancing our understanding on the resistance of this east border upwelling system.

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Section: Methodsmentioning

confidence: 99%

On the robustness of an eastern boundary upwelling ecosystem exposed to multiple stressors

Diogoul

Brehmer

Demarcq

et al. 2021

Sci Rep

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“…Alternatively, numerical or approximate models can be used to include a more realistic swimbladder shape by sectioning into a compound of finite cylinders or meshes 20 . Shape input information for such models require an accurate representation of a real swimbladder shape which can be obtained by the dissection of the species 28 or by means of X-ray scan 29,30 . Even more detailed images can be obtained through Computer Tomography scans (CT) and Magnetic resonance imaging (MRI) 31,32 .…”

Section: Introductionmentioning

confidence: 99%

Characterization of European sprat acoustic backscatter

Palermino,

Gastauer,

Felice

et al. 2024

Preprint

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In fisheries acoustics, the identification of targets and precise translation of acoustic energy into biological meaningful metrics remains a challenge. Backscattering cross-section, or its logarithmic form, Target Strength (TS, dB re 1 m2), is a key parameter in this process. There are numerous studies on commercially important species, but few studies are available on commercially non-important species, such as the European sprat in the Mediterranean Sea. The application of backscattering models can improve our understanding of the acoustic properties of these species, allowing the manipulation of key parameters affecting the TS. Here we applied several backscattering models, on three-dimensional swimbladder shapes derived from Computer Tomography (CT) scans, of sprat collected during the MEDiterranean International Acoustic Survey (MEDIAS) in 2021. The theoretical TS pattern was compared with empirical TS revealing a good fit at 38 and 70 kHz between 0° (broadside incidence) and − 20° and significant differences at higher frequencies and tilt angles. This study provides estimates of the relative frequency response and broadband backscatter of sprat in the Mediterranean Sea. Moreover, the relationship of TS with fish length at 38 kHz yields a new relevant conversion parameter (b20) of -68.3 dB re 1 m2 for European sprat in the Mediterranean Sea.

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Estimation of the Coefficients of the Equation of Acoustic Target Strength Based on the Morphology of Coregonus migratorius (Georgi, 1775) Swim Bladder

Anoshko

Макаров

Попов

et al. 2020

Ûg Ross.: èkol. razvit.

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Aim. The aim of the study was to estimate the coefficients of the equation TSmax=f(SL) considering the characteristics of an acoustic scattering model based on the morphological characteristics of the swim bladder of the Coregonus migratorius (Georgi, 1775). Material and Methods. Ninety‐nine living specimens of C. migratorius served as the study material. For each specimen, the target strength in the cage was measured using an Kongsberg Simrad EY500 echo sounder and the morphology of the swim bladder was studied. Measurements, analysis of images and data were conducted using Image Pro 6.0. Excel and SciLab software resources. Results. We determined the main morphological characteristics of the swim bladder in C. migratorius as well as the correspondence of its dimensions and proportions in relation to the length of the fish’s body. The coefficients of the equation TS=20log(SL)‐60, calculated on the results of the acoustic scattering model of a prolate spheroid, agree well with the coefficients calculated from maximum values obtained in the cage experiment. During the conversion of the coefficients relating to the allometric changes in the length of the swim bladder relative to fish length, the equation TS=23.2log(SL)‐64.4 was obtained. A comparative analysis of the available equations of the target strength for C. migratorius with those obtained in the study was undertaken. Conclusion. The equation obtained on the model of the swim bladder as a prolate spheroid adequately describes the dependence of the maximum values of the target strength on the body length of the C. migratorius and confirms the previously obtained dependence by maximum values of TS in the cage experimental conditions and can serve as a basis for further theoretical studies.

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Estimation of target strength of Sardina pilchardus and Sardinella aurita by theoretical approach

Cited by 3 publications

References 25 publications

On the robustness of an eastern boundary upwelling ecosystem exposed to multiple stressors

On the robustness of an eastern boundary upwelling ecosystem exposed to multiple stressors

Characterization of European sprat acoustic backscatter

Estimation of the Coefficients of the Equation of Acoustic Target Strength Based on the Morphology of Coregonus migratorius (Georgi, 1775) Swim Bladder

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