A Review of Target Strength Estimation Techniques

Ehrenberg, John E.

doi:10.1007/978-94-009-2289-1_17

Cited by 23 publications

(24 citation statements)

References 12 publications

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“…We applied the density-bottle method 13,21 , in which fish mass density, ρ, was determined by evaluating the buoyancy of each sample via a series of 1000 ml beakers containing seawater-glycerol solution of different density, ranging from 1.026 (seawater) to 1.100 g/cm 3 at 0.002 g/cm 3 steps. We defined the value of the bottle in which the fish was neutrally buoyant as fish mass density.…”

Section: Measurements Of Density and Sound-speed Contrastsmentioning

confidence: 99%

“…If the specimen was not neutral in any solution, an average between the last sinking bottle and the first floating bottle was taken. The density contrast of fish body g was obtained by dividing ρ by the density of seawater (1.026 g/cm 3 ). The density of each bottle was confirmed using a glass areometer (15°C standard), and the solution in each bottle was kept at 15°C.…”

Section: Measurements Of Density and Sound-speed Contrastsmentioning

confidence: 99%

“…The value of ρ ranged from 1.043 to 1.051 g/cm 3 (g was 1.017-1.024), with mean value1.048 (g was 1.021) in juvenile fish (3.3-7.4 cm), and ranged from 1.053 to 1.065 g/cm 3 (g was 1.026-1.038), with mean value 1.059 (g was 1.032) in adult fish (7.5-13.2 cm). These values showed significant difference between juvenile and adult (p < 0.005,…”

Section: Density and Sound-speed Contrastsmentioning

confidence: 99%

“…TS has been measured directly with split-or dual-beam echosounders (in situ measurement) for many fish species. 3,4 However, sandeels are difficult to detect as a single target in the field, because they don't have a gas-contained swimbladder that provides high acoustic reflection. 5 There are a few reports on experimental TS measurements (ex situ measurement) of other sandeel species, such as A. hexapterus.…”

Section: Introductionmentioning

confidence: 99%

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Density and sound-speed contrasts, and target strength of Japanese sandeel Ammodytes personatus

et al. 2009

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Sound-speed and density contrasts (h and g, respectively), important acoustic material properties, of Japanese sandeel Ammodytes personatus were measured to estimate theoretical target strength (TS). The measured sound-speed contrast of adult fish varied between 1.016 and 1.023 (mean, 1.020), which showed temperature dependence. The measured density contrast differed significantly between juvenile and adult. The density contrast of juvenile varied between 1.017 and 1.024 (1.021), and that of adult varied between 1.026 and 1.038 (1.032). Using these results, TS at 38 and 120 kHz in the fishing season were estimated by an empirical sound scattering model. TS of an individual fish varied significantly with change of tilt angle. TS of near dorsal aspect (TS max ) and tilt-averaged TS (TS ave ) differed up to 7 dB. At both frequencies, two different TS ave -length relationships (TS ave = a log L + b) were obtained for adult and juvenile. The coefficients of log L of adult were close to 20, suggested that backscattering strength was proportional to the square of body length. These values were larger in juvenile (34.0 at 120 kHz, 56.5 at 38 kHz), suggested that backscattering strength varied drastically with the cube or fifth power of body length.

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Section: Measurements Of Density and Sound-speed Contrastsmentioning

confidence: 99%

Section: Measurements Of Density and Sound-speed Contrastsmentioning

confidence: 99%

Section: Density and Sound-speed Contrastsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Density and sound-speed contrasts, and target strength of Japanese sandeel Ammodytes personatus

et al. 2009

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“…The dual-beam technique was developed in the 1970's for survey applications in fisheries research (see review by Ehrenberg, 1989). Subsequent refinement of the technique has made it feasible for investigators to resolve and analyze echoes returning from individual animals as small as zooplankton (Richter, 1985a;Greene et al, 1989a).…”

mentioning

confidence: 99%

Sound scattering by live zooplankton and micronekton: Empirical studies with a dual-beam acoustical system

Wiebe

Greene

Stanton

et al. 1990

The Journal of the Acoustical Society of America

115

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Measurements and analyses are presented of the backscattering of 420-kHz sound by 43 individual animals of representative zooplanktonic and micronektonic taxa. Direct measurements of an individual's target strength were made with a commercial dual-beam sonar system in an enclosure filled with filtered seawater deployed off a dock at Friday Harbor, Washington. The dependence of target stengths upon individual length, wet weight, and dry weight was investigated. In addition, the target strength and statistical variations of echo amplitude due to variations in shape and orientation of the organism were compared with acoustic scattering models involving different shapes (the general shapes of the sphere, and straight and uniformly bent finite cylinders were used along with attempts to take into account roughness). It was found that: ( 1 ) backscattering cross sections are proportional to volume of the organisms rather than area as would be predicted by a sphere scattering model, (2) mean target strength based on average backscattering cross section is best described by the bent cylinder model whose modal series solution is truncated, and (3) the fluctuations of the echo amplitudes are well described by the Rice probability density function whose shape parameter is related to the randomly rough straight cylinder model. These extensive studies showed conclusively that the elongated animals scattered sound more like elongated targets than spherical ones, thus demonstrating the need for models more sophisticated than the spherical ones routinely used to date. The data and model analyses provide a basis for devising future acoustical data acquisition and processing techniques for bioacoustical field studies.

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Lateral target strength of Antarctic krill

Hewitt

Demer

1996

ICES Journal of Marine Science

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An area of high krill (Euphausia superba Dana) density was continuously monitored with down-looking and side-looking sonars over a period of 24 h. Measurements of volume backscattering strength were used to describe the density of krill with depth and the vertical movement of krill over time. In situ measurements were made of dorsal aspect target strength (TS) and, as krill moved into the near-surface layer (0-15 m), in situ measurements were made of lateral-aspect TS. The probability density function (PDF) of TS measurements made with the down-looking transducer had a mode at approximately 73 dB. The PDF of TS measurements made with the side-looking transducer was broader with a mode at approximately 67 dB. Sampled krill had a bi-modal length distribution with a major mode at 44 mm and a minor mode at approximately 30 mm.1996 International Council for the Exploration of the Sea

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A Review of Target Strength Estimation Techniques

Cited by 23 publications

References 12 publications

Density and sound-speed contrasts, and target strength of Japanese sandeel Ammodytes personatus

Density and sound-speed contrasts, and target strength of Japanese sandeel Ammodytes personatus

Sound scattering by live zooplankton and micronekton: Empirical studies with a dual-beam acoustical system

Lateral target strength of Antarctic krill

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