Target strength estimation by tilt angle and size dependence of rockfish (Sebastes schlegeli) using ex-situ and acoustic scattering model

2017 ◽  
Vol 53 (2) ◽  
pp. 152-159
Author(s):  
Euna YOON ◽  
◽  
Kiseon KIM ◽  
Intae LEE ◽  
Hyeon-Jeong JO ◽  
...  
Keyword(s):  
Tilt Angle ◽  
Size Dependence ◽  
Acoustic Scattering ◽  
Ex Situ ◽  
Target Strength ◽  
Sebastes Schlegeli ◽  
Scattering Model

scholarly journals Acoustic scattering properties of juvenile jack mackerel Trachurus japonicus based on a scattering model and ex situ target strength measurements

2013 ◽  
Vol 79 (3) ◽  
pp. 345-354 ◽  
Author(s):  
TAKESHI NAKAMURA ◽  
AKIRA HAMANO ◽  
KOKI ABE ◽  
HIROKI YASUMA ◽  
KAZUSHI MIYASHITA
Keyword(s):  
Acoustic Scattering ◽  
Ex Situ ◽  
Target Strength ◽  
Jack Mackerel ◽  
Trachurus Japonicus ◽  
Scattering Model

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

2020 ◽  
Vol 15 (1) ◽  
pp. 89-98
Author(s):  
P. N. Anoshko ◽  
M. M. Makarov ◽  
S. B. Popov ◽  
A. I. Degtev ◽  
N. N. Denikina ◽  
...  
Keyword(s):  
Acoustic Scattering ◽  
Morphological Characteristics ◽  
Prolate Spheroid ◽  
The Body ◽  
Target Strength ◽  
Fish Length ◽  
Swim Bladder ◽  
Experimental Conditions ◽  
Scattering Model ◽  
Acoustic Target

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.

scholarly journals Measurements of acoustic-scattering spectra from the whole and parts of Atlantic mackerel

2009 ◽  
Vol 66 (6) ◽  
pp. 1169-1175 ◽  
Author(s):  
Tonje Lexau Nesse ◽  
Halvor Hobæk ◽  
Rolf J. Korneliussen
Keyword(s):  
Frequency Response ◽  
Acoustic Scattering ◽  
Ex Situ ◽  
Target Strength ◽  
Model Parameters ◽  
Acoustic Frequency ◽  
Atlantic Mackerel ◽  
Scattering Spectra ◽  
Laboratory Tank

Abstract Nesse, T. L., Hobæk, H., and Korneliussen, R. J. 2009. Measurements of acoustic-scattering spectra from the whole and parts of Atlantic mackerel. – ICES Journal of Marine Science, 66: 1169–1175. Atlantic mackerel (Scomber scombrus) are weak sound scatterers compared with fish that have swimbladders. Accurate acoustic estimates of mackerel abundance require estimates of target strength. Different parts of mackerel may dominate the backscattering spectra. Mackerel schools are acoustically recognized mainly by backscatter four times stronger at 200 kHz than at 38 kHz. Simulations have established that backscatter from only the flesh and the backbone could explain this frequency response, although there are uncertainties in the model parameters and simplifications. In this paper, experiments conducted in a laboratory tank to investigate the complexity of mackerel backscatter are discussed. Acoustic backscatter was measured over the frequency range 65–470 kHz from individual dead mackerel, and their backbones, heads, and skulls. Backscatter from the backbones was measured at several angles of incidence. Grating lobes (Bragg scattering) appeared at different angles, depending on the acoustic frequency and the spacing of the vertebrae. These lobes were evident in backbone backscatter after propagating through the flesh and can be used, in principle, to determine mackerel size acoustically. The frequency response of individual, ex situ Atlantic mackerel estimated from these measurements did not match that from the measurements of in situ mackerel schools. Further investigation is warranted.

Ex situ acoustic target strength by tilt angle and pulsation of moon jellyfish (Aurelia aurita) using frequency 70 kHz

2015 ◽  
Vol 51 (3) ◽  
pp. 295-301
Author(s):  
Eun–A YOON ◽  
Doo–Jin HWANG ◽  
HIROSE Miyuki ◽  
Kouichi SAWADA ◽  
Yoshiaki FUKUDA ◽  
...  
Keyword(s):  
Tilt Angle ◽  
Aurelia Aurita ◽  
Ex Situ ◽  
Target Strength ◽  
Moon Jellyfish ◽  
Acoustic Target

scholarly journals Ex situ target strength of rockfish (Sebastes schlegeli) and red sea bream (Pagrus major) in the Northwest Pacific

2003 ◽  
Vol 60 (3) ◽  
pp. 538-543 ◽  
Author(s):  
Donhyug Kang ◽  
Doojin Hwang
Keyword(s):  
Red Sea ◽  
Ex Situ ◽  
Sea Bream ◽  
Target Strength ◽  
Northwest Pacific ◽  
Fish Length ◽  
Sebastes Schlegeli ◽  
Red Sea Bream ◽  
Pagrus Major ◽  
Dual Beam

Abstract This study determined the ex situ target strength (TS) of rockfish (Sebastes schlegeli) and red sea bream (Pagrus major) in an artificial seawater tank as a means of helping to estimate fishery resources in coastal areas. TS experiments were conducted at frequencies of 38 kHz (split beam), 120 kHz (split beam), and 200 kHz (dual beam). The species were examined under two conditions: first, live fish confined to a small, net cage; and, second, as free-swimming fish inside a large tank. The study examined 21 rockfish and 20 red sea bream. The data were used to obtain expressions for TS against length and weight for the two species. The relationships between TS and fish length were as follows: for rockfish, TS38 kHz = 20 log10(L) − 67.7 (r = 0.80), TS120 kHz = 20 log10(L) − 74.3 (r = 0.61), TS200 kHz = 20 log10(L) − 72.8 (r = 0.41); and for red sea bream, TS38 kHz = 20 log10(L) − 66.8 (r = 0.86), TS120 kHz = 20 log10(L) − 74.0 (r = 0.65), TS200 kHz = 20 log10(L) − 74.1 (r = 0.83). The TS equations for rockfish and red sea bream as a function of fish weight at 38 kHz were TS38 kHz = 6.75 log10(W) − 56.0 (r = 0.78) and TS38 kHz = 4.08 log10(W) − 49.9 (r = 0.89), respectively. For comparison, calculations using the Helmholtz–Kirchhoff ray-approximation model based on swimbladder morphology were compared with the measured TS. When the tilt angle of the fish is zero, the mean TS from the model is 3–10 dB higher than the experimental results, although the maximum TS values were only 3–4 dB different.

scholarly journals Estimates of acoustic target strength for giant jellyfish Nemopilema nomurai Kishinouye in the coastal Northwest Pacific

2013 ◽  
Vol 71 (3) ◽  
pp. 597-603 ◽  
Author(s):  
Donhyug Kang ◽  
Jusam Park ◽  
Seom-Kyu Jung ◽  
Sungho Cho
Keyword(s):  
Acoustic Scattering ◽  
Ex Situ ◽  
Target Strength ◽  
Northwest Pacific ◽  
Bell Diameter ◽  
Least Squares Regression ◽  
Acoustic Measurements ◽  
Nemopilema Nomurai ◽  
Acoustic Target ◽  
Giant Jellyfish

Abstract Acoustic target strength (TS) measurements were made of ex situ giant jellyfish Nemopilema nomurai Kishinouye at 38 and 120 kHz. These TS data may be useful for developing acoustic scattering models, and surveying giant jellyfish distributions and biomasses. Each jellyfish was tethered in seawater using a monofilament line that vertically penetrated its bell's centre. During the acoustic measurements, an underwater video camera was used to continuously monitor the jellyfish's behaviour. Acoustic measurements were made using split-beam transducers. TS measurements were made of 27 individual jellyfish, but data were analysed for 23 specimens (bell diameter in air, Dair = 21–65 cm) at 38 kHz, and 19 specimens (Dair = 21–46 cm) at 120 kHz, respectively. Least-squares regression fits of TS vs. log(Dair) were TS38kHz = 20•log10Dair–82.7 (r = 0.76) and TS120kHz = 20•log10Dair–86.7 (r = 0.79). The mean TS values at 38 and 120 kHz, using the average Dair = 40.3 cm and 35.5 cm, respectively, were −50.6 and −55.7 dB. The reduced TS, a function of the ratio of Dair to wavelength (λ), was RTS(Dair/λ) = −6.1•log10(Dair/λ) –36.1 (r = 0.51). These RTS values decreased with increasing Dair/λ. Symbiotic medusa shrimp (Latreutes anoplonyx Kemp) contributed negligible bias to our TS measurements of giant jellyfish. These ex situ TS measurements may be used in acoustic surveys to estimate the distributions and biomasses of N. nomurai.

scholarly journals The influence of tilt angle on the acoustic target strength of the Japanese common squid (Todarodes pacificus)

2005 ◽  
Vol 62 (4) ◽  
pp. 779-789 ◽  
Author(s):  
Donhyug Kang ◽  
Tohru Mukai ◽  
Kohji Iida ◽  
Doojin Hwang ◽  
Jung-Goo Myoung
Keyword(s):  
Tilt Angle ◽  
Empirical Relationship ◽  
Ex Situ ◽  
Target Strength ◽  
Todarodes Pacificus ◽  
Common Squid ◽  
Acoustic Target ◽  
The Mean ◽  
Highly Correlated ◽  
Japanese Common Squid

Abstract To measure the influence of changes in tilt angle on the acoustic target strength (TS) of the Japanese common squid (Todarodes pacificus), we conducted a series of experiments to estimate TS in relation to tilt angle and swimming angle. Swimming angle was measured in a seawater tank using two infrared, underwater cameras under dark conditions. Ex situ measurements of TS in relation to tilt angle on live specimens using a fishhook and cage method were then conducted at 38 and 120 kHz; mantle length (ML) ranged from 21 to 27 cm (mean 24.75 cm). For the more precise TS measurement with tilt angle, another set of ex situ TS measurements relative to tilt angle was made at 38 and 120 kHz on tethered, anesthetized specimens in seawater. The mean swimming angle was −17.7° (±12.7° s.d.). The mean TS varied from −48.6 to −44.6 dB and was relatively higher at 120 kHz than at 38 kHz, in the order of 0.7 and 2.5 dB. The empirical relationship between TS (dB) and ML (cm) is given by TS = 20 log10(ML) − 75.4 (r = 0.81) at 38 kHz or TS = 20 log10(ML) − 73.5 (r = 0.64) at 120 kHz. Based on the tethered method for the anesthetized squid, the mean standardized TS values (b20) were found to be highly correlated with the tilt angle, and the resultant fitted equations for b20 were expressed as: b20 = −73.3 + 0.48 × Θ + 0.0122 × Θ2 + 0.00016 × Θ3 for 38 kHz and b20 = −72.6 + 0.53 × Θ + 0.0134 × Θ2 + 0.00014 × Θ3 for 120 kHz, where Θ is the negative tilt angle in degrees. The mean TS based on the measurements using live squid was higher than that of tethered measurements, i.e., 2.6 dB at 38 kHz and 4.0 dB at 120 kHz. The higher mean TS in the ex situ measurements for the live squid can be explained by the influence of the low tilt angle on the overall TS data. The results can be used to understand the influence of tilt angle on the TS of Todarodes pacificus and thus improve the accuracy of biomass estimates.

Acoustic scattering characteristic depend on length and swimming angle of scorpion fish (Sebasiscus marmoratus) based on ex-situ method

2016 ◽  
Vol 9 (1) ◽  
pp. 1
Author(s):  
Yu-Geun JI ◽  
Kyu-Kyeong SHIM ◽  
Keon-Woo SONG ◽  
Eun-A YOON ◽  
Doo-Jin HWANG
Keyword(s):  
Acoustic Scattering ◽  
Ex Situ ◽  
Scorpion Fish ◽  
Scattering Characteristic

An acoustic scattering model for stratification interfaces

2021 ◽  
Vol 150 (6) ◽  
pp. 4353-4361
Author(s):  
Elizabeth Weidner ◽  
Thomas C. Weber
Keyword(s):  
Acoustic Scattering ◽  
Scattering Model
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