Wideband studies of shallow-water acoustic attenuation due to fish

Ching, P.A.; Weston, D. E.

doi:10.1016/0022-460x(71)90101-5

Cited by 24 publications

(20 citation statements)

References 4 publications

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“…It is noteworthy that the hypothesis that absorptivity due to schools of sardines at night is small is consistent with Ching and Weston's (1971) previously reported experimental observations. Their measurements revealed the presence of a single absorption line at night, which was consistent with the resonance frequency of dispersed sardines near the surface.…”

Section: The Line At 09 Khz At Night: Probably Dispersed Anchoviessupporting

confidence: 88%

“…The difference between measurements and calculations is within experimental uncertainty (Diachok, 1999). It is noteworthy that the resonance frequency of 16 cm long sardines at this site, 1.3 kHz, is comparable to the frequencies of absorption lines attributed to dispersed adult sardines at night in the Bristol Channel (Ching and Weston, 1971).…”

Section: Resonance Frequencies Of Individual Fish and Fish In Schoolsmentioning

confidence: 78%

“…This procedure is quite robust; it is not dependent on a theoretical model to calculate the replica field. This procedure is basically the same as the one employed by Ching and Weston (1971).…”

Section: The Classification Of Absorption Linesmentioning

confidence: 95%

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Estimation of the number density of fish from resonance absorptivity and echo sounder data

Diachok¹

2001

ICES Journal of Marine Science

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Diachok, O., Liorzou, B., and Scalabrin, C. 2001. Estimation of the number density of fish from resonance absorptivity and echo sounder data. -ICES Journal of Marine Science, This paper provides a comparison of number densities (number per m 2 in the horizontal plane) of pelagic fish, which were derived from acoustic absorptivity measurements and nearly coincident echo sounder and trawling data. Absorptivity measurements were made with a broadband source (between frequencies of 0.6 and 5.0 kHz) as a function of time between a fixed source and a fixed receiver separated by 12 km in relatively shallow (83 m) water. The sardine (Sardina pilchardus Walbaum) was the dominant species at this measurement site. The second most common species was the anchovy (Engraulis encrasicolus Linnaeus); there were approximately twice as many sardines as anchovies. The number densities of all other species were small. Strong absorption lines were evident at the resonance frequencies of dispersed sardines. The frequencies of these absorption lines changed in accordance with the vertical migration of sardines at twilight. A correction for the influence of anchovies on the absorption line, which was dominated by dispersed sardines at night, was applied to the absorption-based estimate. Initial echo sounder based estimates of number densities, which were based on a ''universal'' pressure independent equation of target strength, were corrected for pressure dependence, attenuation by near surface bubbles, and avoidance. The corrected absorption based number density of sardines (1.4 m 2 ) was in excellent agreement with the average corrected echo sounder based estimate (1.0 m 2 ). These results suggest the possibility of estimating number densities from broadband, tomographic, transmission-loss measurements over large areas.

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Section: The Line At 09 Khz At Night: Probably Dispersed Anchoviessupporting

confidence: 88%

Section: Resonance Frequencies Of Individual Fish and Fish In Schoolsmentioning

confidence: 78%

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Estimation of the number density of fish from resonance absorptivity and echo sounder data

Diachok¹

2001

ICES Journal of Marine Science

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“…It includes a critical analysis of the classification of spectral absorption lines with the constraint, that classifications must be consistent with echo sounder based estimates of number densities. During FY 99 I also completed analysis of previously reported measures of the seasonal variability of resonance frequencies (Ching and Weston, 1971).…”

Section: Work Completedmentioning

confidence: 99%

“…The theoretical equation of the resonance frequency of dispersed sardines, which is a function of the effective radius and eccentricity of the swim bladder and the pressure , was applied to Ching and Weston's (1971) measurements of the seasonal variability of resonance frequencies of absorption lines due to sardines. Results of this analysis suggest that sardines occupy depths at night, which approximately coincide with the depths of phytoplankton maxima.…”

Section: Depths Of Sardines and Contours Of Phytoplankton Concentratimentioning

confidence: 99%

Bioacoustic Absorption Spectroscopy

Diachok¹

1999

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LONG TERM GOALDemonstrate the potential of bioacoustic absorption spectroscopy for tomographic mapping of the bioacoustic parameters of fish with swim bladders in shallow water. OBJECTIVESDevelop an acoustic propagation model that accounts for bioacoustic absorptivity due to fish with swim bladders on transmission loss as a function of frequency over the frequency range 0.5-5.0 kHz in shallow water. Develop a bioacoustic model that accounts for the resonance frequencies of absorption lines, which are due to dispersed pelagic fish, and schools of pelagic fish with swim bladders. Develop a model of the seasonal variability of resonance frequencies. Demonstrate consistency between absorptivity and echo sounder based estimates of number densities. APPROACHInvert bioacoustic parameters from transmission loss data recorded during Modal Lion, by matching theoretical computations with data. Demonstrate consistency between absorptivity and echo sounder based estimates of number densities of sardines in the Gulf of Lion. Develop an analytical model to account for the frequencies of measured absorption lines by extending a previously published theory of the resonance frequency of "bubble clouds". Design broadband, long term, autonomous sources and receivers, that will permit long term monitoring of bioacoustic parameters. Conduct new bioacoustic absorptivity experiments in littoral seas in co-operation with fisheries biologists. The first planned experiment will be in the seas off California in co-operation with the Southwest Fisheries Science Center of NOAA's National Marine Fisheries Service. These experiments will be designed to investigate the "signatures" of the two major classes of fish with swim bladders physotomes (volumes vary inversely with pressure) and physoclists (volumes are independent of pressure) in time frequency space. Simulate effects of absorptivity on transmission loss vs. time and frequency of physostomes and physoclists. Apply model to new and previously published bioacoustic absorptivity measurements, derive bioacoustic parameters, and demonstrate consistency with biological measurements.

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Spatial Distributions and Ecology of Pelagic Fish

Horwood

Cushing

1978

Spatial Pattern in Plankton Communities

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Wideband studies of shallow-water acoustic attenuation due to fish

Cited by 24 publications

References 4 publications

Estimation of the number density of fish from resonance absorptivity and echo sounder data

Estimation of the number density of fish from resonance absorptivity and echo sounder data

Bioacoustic Absorption Spectroscopy

Spatial Distributions and Ecology of Pelagic Fish

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