Implications of a new acoustic target strength for abundance estimates of Antarctic krill

Abstract Pedersen, G., Godø, O. R., Ona, E., and Macaulay, G. J. 2011. A revised target strength–length estimate for blue whiting (Micromesistius poutassou): implications for biomass estimates. – ICES Journal of Marine Science, 68: 2222–2228. Acoustic abundance estimates of blue whiting have generally been higher than estimates based on catch data. One explanation has been that the relationship between acoustic target strength (TS) and length is too low and hence overestimates the number of fish. Measurements of TS were conducted during surveys of blue whiting in March/April 2003–2007 to the west of the British Isles from several different measurement platforms, and also during August 2005 in the Norwegian Sea. Results from these experiments confirm the view that the existing TS–length relationship is too low. A new TS–length relationship is proposed that is ∼5 dB higher. Blue whiting TS is considerably higher than observed and modelled for a similar species, southern blue whiting (Micromesistius australis).

Download Full-text

Acoustic Target Strength Analysis for Underwater Vehicles Covering Near Field Spherical Wave Source Originated Multiple Bounce Effects

Journal of the Society of Naval Architects of Korea ◽

10.3744/snak.2010.47.2.196 ◽

2010 ◽

Vol 47 (2) ◽

pp. 196-209

Author(s):

Byung-Gu Cho ◽

Suk-Yoon Hong ◽

Hyun-Wung Kwon

Keyword(s):

Near Field ◽

Spherical Wave ◽

Underwater Vehicles ◽

Target Strength ◽

Strength Analysis ◽

Wave Source ◽

Acoustic Target

Download Full-text

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

Proceedings of the Institution of Mechanical Engineers Part M Journal of Engineering for the Maritime Environment ◽

10.1177/1475090218779292 ◽

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.

Download Full-text

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

Trudy VNIRO ◽

10.36038/2307-3497-2021-184-73-86 ◽

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

Download Full-text

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

Fisheries Research ◽

10.1016/j.fishres.2018.05.008 ◽

2018 ◽

Vol 206 ◽

pp. 79-84 ◽

Cited By ~ 1

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

Download Full-text

Acoustic Target Strength of the Endangered Chinese Sturgeon (Acipenser sinensis) by Ex Situ Measurements and Theoretical Calculations

Applied Sciences ◽

10.3390/app8122554 ◽

2018 ◽

Vol 8 (12) ◽

pp. 2554 ◽

Cited By ~ 1

Author(s):

Hui Zhang ◽

Junyi Li ◽

Chongrui Wang ◽

Chengyou Wang ◽

Jinming Wu ◽

...

Keyword(s):

Theoretical Calculations ◽

Breeding Population ◽

Ex Situ ◽

Target Strength ◽

Effective Management ◽

Chinese Sturgeon ◽

Acipenser Sinensis ◽

Acoustic Target ◽

The Mean ◽

Db Difference

The Chinese sturgeon, Acipenser sinensis, is a large anadromous and highly endangered protected species. The assessment of its breeding population in the Yangtze River is critically important for effective management and population preservation. Currently, hydroacoustic methods have been widely used to study the adult sturgeons in the river, whereas the acoustic target strength (TS) characteristics of the species have not been studied. In this study, the TS of Chinese sturgeon was carefully evaluated both by ex situ measurements and theoretical calculations. Six Chinese sturgeons (Body Length (BL): 74.0−92.6 cm) were measured by a 199 kHz split echosounder in a 10-m deep net cage. The computed tomography of a Chinese sturgeon (BL: 110.0 cm) was conducted and the Kirchhoff ray mode (KRM) method was used to estimate the theoretical TS. As a result, the mean ex situ TS range of the six specimens was from −26.9 to −31.4 dB, which was very close to the KRM estimation (~1 dB difference). Then, the KRM method was used to predict the TS of Chinese sturgeon as a function of BL in six frequencies commonly used in freshwater environments and to estimate the TS of a representative adult Chinese sturgeon (250 cm) as a function of frequency and tilt angle. This study can provide a good basis for future hydroacoustic studies on the critically endangered Chinese sturgeon.

Download Full-text