scholarly journals In situ acoustic target strength measurements of tuna associated with a fish aggregating device

2000 ◽  
Vol 57 (4) ◽  
pp. 911-918 ◽  
Author(s):  
E Josse
Keyword(s):  
Target Strength ◽  
Acoustic Target

scholarly journals The study of the acoustic target strength of Chub mackerel in the northwestern Pacific Ocean in situ

Trudy VNIRO ◽  
2021 ◽  
Vol 184 ◽  
pp. 73-86
Author(s):  
M.Yu. Kuznetsov ◽  
◽  
V.I. Polyanichko ◽  
E.V. Syrovatkin ◽  
I.A. Ubarchuk ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Target Strength ◽  
Northwestern Pacific ◽  
Chub Mackerel ◽  
Northwestern Pacific Ocean ◽  
Acoustic Target

First in situ estimates of acoustic target strength of Antarctic toothfish (Dissostichus mawsoni)

2018 ◽  
Vol 206 ◽  
pp. 79-84 ◽  
Author(s):  
Richard L. O’Driscoll ◽  
Simonepietro Canese ◽  
Yoann Ladroit ◽  
Steve J. Parker ◽  
Laura Ghigliotti ◽  
...  
Keyword(s):  
Target Strength ◽  
Antarctic Toothfish ◽  
Dissostichus Mawsoni ◽  
Acoustic Target

Determination of Composition and Vertical Structure of Fish Communities Using in situ Measurements of Acoustic Target Strength

1994 ◽  
Vol 51 (1) ◽  
pp. 99-109 ◽  
Author(s):  
M. Barange ◽  
I. Hampton ◽  
S. C. Pillar ◽  
M. A. Soule
Keyword(s):  
South African ◽  
Size Structure ◽  
Fish Communities ◽  
Target Strength ◽  
Small Scale ◽  
Good Correspondence ◽  
Structure And Dynamics ◽  
Acoustic Target

A split-beam echo-sounder was used to estimate in situ acoustic target strengths (TS) of fish from a number of different fish communities on the South African continental shelf. The TS and size distributions (obtained by aimed trawling) were used to describe the size structure and vertical distribution of these communities. TS distributions obtained from several monospecific populations of juvenile Cape hake (Merluccius capensis), the dominant species present, were self-consistent, and there was good correspondence between modes in the TS and length distributions of juvenile hake, adult round herring (Etrumeus whiteheadi), anchovy (Engraulis capensis) recruits, pelagic goby (Sufflogobius bibarbatus), horse mackerel (Trachurus trachurus capensis), and ribbon fish (Lepidopus caudatus). Average TS values for all these species, both per individual and normalized by weight, are presented and compared with published values. The use of TS information in studies of the small-scale community structure and dynamics of fish populations is discussed. It is concluded that the method can be effective on low-density, multispecific assemblages such as those in our study, avoiding many of the pitfalls of conventional net sampling.

scholarly journals In situ target strength estimates of optically verified southern blue whiting (Micromesistius australis)

2012 ◽  
Vol 70 (2) ◽  
pp. 431-439 ◽  
Author(s):  
Richard L. O'Driscoll ◽  
Johannes Oeffner ◽  
Adam J. Dunford
Keyword(s):  
New Zealand ◽  
Confidence Interval ◽  
Fork Length ◽  
Target Strength ◽  
Blue Whiting ◽  
Acoustic Target ◽  
The Mean ◽  
The Relationship ◽  
Immature Fish

Abstract O'Driscoll, R. L., Oeffner, J., and Dunford, A. J. 2013. In situ target strength estimates of optically verified southern blue whiting (Micromesistius australis) – ICES Journal of Marine Science, 70: 431–439. Estimates of the acoustic target strength (TS) of southern blue whiting (Micromesistius australis) at 38 kHz were obtained using an autonomous acoustic–optical system (AOS) mounted on a demersal trawl. Data were collected from aggregations of spawning adult [mean fork length (FL) 34.4 cm] and immature (mean FL 24.6 cm) southern blue whiting south of New Zealand. Mean TS was estimated from 162 tracks containing 695 echoes from targets identified from video as southern blue whiting. The mean TS was –37.9 dB with a 95% confidence interval (CI) of –39.7 to –36.6 dB for 21 immature fish and –34.6 dB (95% CI –35.4 to –34.0 dB) for 141 adults. A logarithmic fit through the mean TS values produced a TS–fork length (FL) relationship from optically verified targets of TS = 22.06 log10FL – 68.54. This new relationship gives TS values within 1 dB of those estimated using the relationship recently adopted by ICES for blue whiting (Micromesistius poutassou) of TS = 20 log10TL – 65.2 (where TL is total length) obtained from in situ measurements, but higher values than those estimated from the previous relationship for southern blue whiting of TS = 38 log10FL – 97, which was based on swimbladder modelling.

Convergence of Acoustic, Optical, and Net-Catch Estimates of Euphausiid Abundance: Use of Artificial Light to Reduce Net

1993 ◽  
Vol 50 (2) ◽  
pp. 334-346 ◽  
Author(s):  
D. Sameoto ◽  
N. Cochrane ◽  
A. Herman
Keyword(s):  
Target Strength ◽  
Sampling System ◽  
Remotely Operated Vehicle ◽  
Acoustic Backscattering ◽  
Video Cameras ◽  
Acoustic Target ◽  
Avoidance Reactions ◽  
Theoretical Scattering ◽  
System Operating

Euphausiid concentrations in the Scotian Shelf basins were sampled with BIONESS, a multinet sampling system, and quantitatively assessed simultaneously with an in situ optical zooplankton counter (OPC) mounted on BIONESS and with an acoustic backscattering system operating simultaneously at 50, 122, and 200 kHz. Supplementary observations were made with vertically dropped video cameras and video and 35-mm frame cameras mounted on a remotely operated vehicle (ROV). The use of a light source on BIONESS during sampling increased the catch of euphausiids by 10–20 times by reducing active avoidance reactions to the net. Consequently, conventional net sampling has greatly underestimated euphausiid concentrations, a conclusion suggested by previous acoustic measurements. Experimental acoustic target strengths for 28-mm euphausiids averaged −77.5, −73.4, and −68.4 dB at 50, 122, and 200 kHz, respectively, using measured Sv levels and assuming 100% net sampling efficiency. Theoretical scattering models based on randomly oriented cylinders require the euphausiids to be oriented within about 5° of the horizontal to approximate both the experimentally observed target strength amplitudes and their frequency dependence. Acoustic interpretation has been enhanced by incorporation of transducer sensitivity versus temperature corrections and modeling techniques that allow for finite transducer beam widths.

In situ acoustic target strength of anchovy kilka ( Clupeonella engrauliformis ) in the Caspian Sea (Iran)

2017 ◽  
Vol 186 ◽  
pp. 311-318 ◽  
Author(s):  
Parviz Zare ◽  
Svetlana M. Kasatkina ◽  
Sergey V. Shibaev ◽  
Hassan Fazli
Keyword(s):  
Caspian Sea ◽  
Target Strength ◽  
The Caspian Sea ◽  
Acoustic Target

Development of acoustic target strength near-field equation for underwater vehicles

2018 ◽  
Vol 233 (3) ◽  
pp. 714-721
Author(s):  
Jae-Yong Kim ◽  
Suk-Yoon Hong ◽  
Byung-Gu Cho ◽  
Jee-Hun Song ◽  
Hyun-Wung Kwon
Keyword(s):  
Field Equation ◽  
Plane Wave ◽  
Pressure Field ◽  
Near Field ◽  
Target Strength ◽  
Detection Capability ◽  
Weapon Systems ◽  
Active Sonar ◽  
Acoustic Target ◽  
Definition Of

For modern weapon systems, the most important factor in survivability is detection capability. Acoustic target strength is a major parameter of the active sonar equation. The traditional target strength equation used to predict the re-radiated intensity for the far field is derived with a plane-wave assumption. In this study, a near-field target strength equation was derived without a plane-wave assumption for a polygonal plate. The target strength equation for polygonal plates, which is applicable to the near field, is provided by the Helmholtz–Kirchhoff formula that is used as the primary equation for solving the re-radiated pressure field. A generalized definition of the sonar cross section is suggested that is applicable to the near field. In comparison experiments for a cylinder, the target strength equation for polygonal plates in near field was executed to verify the validity and accuracy of the analysis. In addition, an underwater vehicle model was analyzed with the developed near-field equation to confirm various parameter effects such as distance and frequency.

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