Comparing acoustic model predictions to <i>in situ</i> backscatter measurements of fish with dual‐chambered swimbladders

Horne, John K.; Walline, P.; Jech, J. Michael

doi:10.1111/j.1095-8649.2000.tb00474.x

Cited by 32 publications

(9 citation statements)

References 37 publications

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“…Compared with the ex situ measurements, the KRM backscatter model overestimates the TS of most hake, especially at near-horizontal orientations. Overestimates of TS predictions have been observed in other model-to-measurement comparisons (e.g., Horne et al 2000;Kang and Hwang 2003;Lilja et al 2004). Owing to the complexity of sound scattering from a biological target, there are numerous potential causes for these discrepancies.…”

Section: Discussionmentioning

confidence: 87%

Comparison of in situ, ex situ, and backscatter model estimates of Pacific hake (Merluccius productus) target strength

Henderson¹,

Horne²

2007

Can. J. Fish. Aquat. Sci.

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To convert acoustic energy into estimates of fish density, the target strength (TS) of a representative fish must be known. TS is a measure of the acoustic reflectivity of a fish, which is variable depending on the presence of a swimbladder, the size of the fish, its behavior, morphology, and physiology. The most common method used to estimate the TS of a fish is a TS-to-length empirical regression, with TS values increasing with fish length. This study uses in situ and ex situ TS measurements and a backscatter model to develop TS-to-length conversions for Pacific hake (Merluccius productus). Results from in situ and ex situ measurements had regression intercepts 4-6 dB lower than the previous Pacific hake TS-to-length regression. These differences suggest that an individual hake reflects 2.5-4 times less acoustic energy than was previously estimated.Résumé : Pour pouvoir convertir l'énergie acoustique en estimations de la densité de poissons, il est nécessaire de connaître l'intensité de la cible (TS) constituée par un poisson représentatif. TS est une mesure de la réflectivité acoustique d'un poisson et elle varie en fonction de la présence d'une vessie natatoire, de la taille du poisson, de son comportement, de sa morphologie et de sa physiologie. La méthode la plus couramment utilisée pour estimer la TS d'un poisson se base sur une relation empirique entre TS et la longueur dans laquelle les valeurs de TS augmentent en fonction de la longueur du poisson. Notre étude utilise des mesures in situ et ex situ de TS et un modèle de rétrodiffusion pour mettre au point une méthode de conversion des TS en longueurs chez le merlu du Pacifique (Merluccius productus). Les résultats de nos mesures in situ et ex situ donnent, dans les régressions, des valeurs de l'ordonnée à l'origine de 4-6 dB inférieures à celles des régressions faites antérieurement reliant TS à la longueur chez le merlu du Pacifique. Ces différences laissent croire que la rétrodiffusion d'énergie acoustique faite par un merlu individuel est de 2,5-4 fois moins importante que dans les estimations antérieures.[Traduit par la Rédaction] Henderson and Horne 1794

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Section: Discussionmentioning

confidence: 87%

Comparison of in situ, ex situ, and backscatter model estimates of Pacific hake (Merluccius productus) target strength

Henderson¹,

Horne²

2007

Can. J. Fish. Aquat. Sci.

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“…Most empirical TS measurements have traditionally been derived from in situ or ex situ measurements. However, with advancements in computational power, modelling techniques have become widely used (Horne et al 2000;Fässler et al 2013;Scoulding et al 2015). Previous studies have successfully used CT scans to derive morphological representations of swimbladders as an alternative to time consuming and more expensive methods such as microtoming or MRI scans (Reeder et al 2004;Peña 2008;Fässler et al 2013;Scoulding et al 2015).…”

Section: Discussionmentioning

confidence: 99%

“…29, 301 (2016) (MacLennan 1990) representation. Advances in computational power have enabled the development of complex theoretical scattering models that have been used to validate empirical TS measurements, based on morphological information of a given species in their environment (Horne et al 2000;Foote and Francis 2002;Fässler et al 2009Fässler et al , 2013. Still, the stochastic nature of TS has to be acknowledged and the resulting variance and its influence on biomass estimates have to be taken into account.…”

Section: Introductionmentioning

confidence: 99%

Target strength estimates of red emperor (Lutjanus sebae) with Bayesian parameter calibration

Gastauer

Scoulding

Fässler

et al. 2016

Aquat. Living Resour.

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Red emperor (Lutjanus sebae) is a long-lived tropical demersal snapper which is widely distributed in the Western Pacific and Indian Ocean. Despite the commercial and recreational importance of the species for the Northern Demersal Scalefish Fishery off the Northwest coast of Western Australia, we still lack a thorough understanding of its distribution and abundance in the area. To better understand the acoustic scattering properties of red emperor its acoustic backscattering characteristics were modelled based on swimbladder and body morphology, determined using computed tomography scans. A Kirchhoff-ray mode approximation was coupled with empirical (ex situ) measurements of target strength (TS) obtained from a 38 and 120 kHz split-beam echosounder on board a fishing vessel. Bayesian methods were used for model parameter calibration, which provided uncertainty estimates for some of the TS-model parameters. The derived TS-length relationships were 19.7 log 10 (L) -75.5 (C.I. 5.9 dB) at 120 kHz and 14.6 log 10 (L) -64.9 (C.I. 5.8 dB) at 38 kHz. The study demonstrated that small commercial fishing vessels can be used to conduct ex situ experiments and target strength modelling can be effectively based on computer tomography scans. This relatively low cost approach could be applied to other species.

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“…Allometric growth by individual animals will decrease accuracy of TS to L T conversions used in acoustic‐based abundance estimates. Data used to quantify species‐specific relationships between TS and fish length are acquired using in situ TS measurements from animals in low‐density aggregations (Burczynski et al , 1987), or by measuring backscatter from tethered (Nakken & Olsen, 1977; Horne et al , 2000) or caged (Edwards & Armstrong, 1984) individuals of known lengths. These methods provide snapshots of TS characteristics from groups of animals but do not track development among individuals.…”

Section: Discussionmentioning

confidence: 99%

Acoustic ontogeny of a teleost

Horne

2008

Journal of Fish Biology

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The influence of growth on the intensity and variability of acoustic echoes from individuals and groups of a teleosts was quantified using Donaldson trout (rainbow-steelhead hybrid) Oncorhynchus mykiss. Fish growth was linear in total length (L T ) and quadratic in mass. Dorsal swimbladder area increased exponentially with L T . Allometric growth ratio (i.e. k) values of swimbladder length linearly increased with L T . Average swimbladder volumes occupied 3-6% of fish body volume and increased exponentially with L T . The aspect angle that resulted in the maximum average acoustic intensity from the group shifted from 80 to 86°through the experimental period. Mean echo intensities increased at both 38 and 120 kHz as mean L T increased. Predicted echo intensities at 38 kHz exceeded that at 120 kHz at L T <150 mm but were less than that predicted at 120 kHz at L T >280 mm. Generalized additive mixed models using L T , swimbladder angles and lateral elongation ratios of fish bodies were better predictors of echo intensities than L T alone.

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Comparing acoustic model predictions to in situ backscatter measurements of fish with dual‐chambered swimbladders

Cited by 32 publications

References 37 publications

Comparison of in situ, ex situ, and backscatter model estimates of Pacific hake (Merluccius productus) target strength

Comparison of in situ, ex situ, and backscatter model estimates of Pacific hake (Merluccius productus) target strength

Target strength estimates of red emperor (Lutjanus sebae) with Bayesian parameter calibration

Acoustic ontogeny of a teleost

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