Examining the relationship between morphological variation and modeled broadband scattering responses of reef-associated fishes from the Southeast United States

Boswell, Kevin M.; Pedersen, Geir; Taylor, James C.; LaBua, Savannah; Patterson, William F.

doi:10.1016/j.fishres.2020.105590

Cited by 5 publications

(3 citation statements)

References 48 publications

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“…Among models, numerical ones such as BEM and FEM are considered the more precise than approximate models such as the KRM 20 but they are computationally expensive (several hours or days for a single fish using consumer equipment), as a consequence, approximation models are often preferred. However, several authors demonstrated their inability to capture finer scale variations which can affect the overall backscatter 20,47 when compared to numerical models 52 . In this study, we demonstrated small divergences between numerical models (FEM and BEM) and approximate analytical KRM model in the broadband pattern up to 2 dB in mean TS at 38 kHz.…”

Section: Discussionmentioning

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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Section: Discussionmentioning

confidence: 99%

Characterization of European sprat acoustic backscatter

Palermino,

Gastauer,

Felice

et al. 2024

Preprint

View full text Add to dashboard Cite

show abstract

Section: Discussionmentioning

confidence: 99%

“…Applying acoustic techniques to monitor fine‐scale distribution of multispecies assemblages around benthic structure, such as reefs, still presents significant challenges (Boswell et al 2020), as it is common for multiple species to forage together in the water column (Lukoschek and McCormick 2000). This school heterogeneity significantly complicates traditional fisheries acoustic approaches (Boswell et al 2020). Although there exists high variability in translating school thickness to actual fish abundance (Zwolinski et al 2009), the high correlation of this variable with mean volume backscatter from the split‐beam echosounder suggests that school thickness can be a useful representation for the relative distribution of schools.…”

Section: Discussionmentioning

confidence: 99%

Characterizing the three‐dimensional distribution of schooling reef fish with a portable multibeam echosounder

Holland

Becker

Smith

et al. 2021

Limnology & Ocean Methods

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Multispecies schools of small planktivorous fishes are important constituents of reefs and coastal infrastructure; however, determining the extent and distribution of these schools is challenging. Here, we describe a novel use of a low-cost portable multibeam echosounder from a small vessel, which can concurrently measure detailed bathymetry and the distribution of mid-water targets with high spatial accuracy, regardless of light availability or water clarity. Fish abundance and biomass are not easily quantified by multibeam echosounders, so we developed a new metric for delineating the gridded horizontal distribution of school thickness, and assessed the metric's efficacy by examining its correlation with mean volume backscattering strength derived from a calibrated 38 kHz split-beam echosounder (R = 0.67). We measured the distribution of fish school thickness around clusters of large concrete modules of an artificial reef using a multibeam echosounder, complemented with underwater video to aid species identification. The mean distribution of school thickness was mapped around the reef field with generalized additive mixed models. Model spatial predictions indicated schools aggregated around module clusters, rather than individual modules. Dynamic schools of fish in relatively shallow coastal waters ( 30 m) can be surveyed over 400,000 m 2 at 3 m s −1 in just 60 min. Portable multibeam echosounders are an accessible and valuable addition to quantifying the dynamic distributions of coastal fishes around features with high vertical relief.

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Taxonomical classification of reef fish with broadband backscattering models and machine learning approaches

Roa

Pedersen

Bollinger

et al. 2022

The Journal of the Acoustical Society of America

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Commercially available broadband echosounders have the potential to classify acoustic targets based on their scattering responses, which are a function of their species-specific morphological and physiological properties. This is particularly important in complex environments with biologically diverse fish assemblages. Using theoretical acoustic scattering models among 130 fishes across six species, we examine the potential to classify reef fish based on the fine-scale gas-bearing swim bladder morphology quantified from three-dimensional computed-tomography models. Modeled echoes of the swim bladder for an incident broadband sound source (30–200 kHz) and across a range of orientation angles (±44°) are acoustically simulated using the boundary element method. Backscatter models present characteristics that are consistent within species and distinguishable among them. Broadband and multifrequency echoes are classified and compared with Bayesian, support vector machine, k-nearest neighbor, and convolutional neural network estimators. Classifiers have higher accuracies (>70%) when noise is not present and perform better when applied to broadband spectra than multifrequency data (42, 70, 100, 132, 160, 184 kHz). The modeling and classification approaches presented indicate that a taxonomic distinction based on morphologically dependent scattering responses is possible and may provide the capacity to acoustically discriminate among fish species.

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Examining the relationship between morphological variation and modeled broadband scattering responses of reef-associated fishes from the Southeast United States

Cited by 5 publications

References 48 publications

Characterization of European sprat acoustic backscatter

Characterization of European sprat acoustic backscatter

Characterizing the three‐dimensional distribution of schooling reef fish with a portable multibeam echosounder

Taxonomical classification of reef fish with broadband backscattering models and machine learning approaches

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