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Journal ArticleDOI

Dorsal‐Aspect Target Strength of an Individual Fish

Richard H. Love
- 01 Mar 1971 - 
- Vol. 49, pp 816-823
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TLDR
In this paper, the authors described experiments in which the dorsal-aspect target strengths of a number of individual teleostean fishes of eight species were measured at various frequencies and combined with results from eight other sources and an empirical equation approximating the dorsal • aspect target strength of an individual fish determined for 0.7⩽L/λ/λ ⩽90, where L is the fish length and λ is the incident acoustic wavelength.
Abstract
Experiments are described in which the dorsal‐aspect target strengths of a number of individual teleostean fishes of eight species were measured at various frequencies. The results of these experiments indicate that the variations of target strength with frequency are different for fishes in two major teleostean groups, the malacopterygians and the acanthopterygians. These results are combined with results from eight other sources and an empirical equation approximating the dorsal‐aspect target strength of an individual fish determined for 0.7⩽L/λ⩽90, where L is the fish length and λ is the incident acoustic wavelength. The combined results are compared to similar results for the maximum side‐aspect target strength of an individual fish, and curves showing the trend of dorsal‐aspect and maximum side‐aspect acoustic cross sections of an individual swimbladder‐bearing fish are presented for all L/λ⩽90.

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Citations
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Journal ArticleDOI

Fish target strengths for use in echo integrator surveys

TL;DR: In this paper, in situ measurements of fish target strength are selected for use in echo integrator surveys at 38 kHz, and the results are expressed through equations in which the mean target strength TS is regressed on the mean fish length l in centimeters.
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Prey dynamics affect foraging by a pelagic predator (Stenella longirostris) over a range of spatial and temporal scales

TL;DR: The overlap of Hawaiian spinner dolphins and their prey at many temporal and spatial scales, ranging from several minutes to an entire night and 20 m to several kilometers, indicates that the availability of truly synoptic data may fundamentally alter the authors' conclusions about pelagic predator-prey interactions.
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An operational system for processing and visualizing multi-frequency acoustic data

TL;DR: In this paper, a special version of the Simrad EK500 multi-frequency, split-beam echosounder and the Bergen Echo Integrator (BEI) post-processing system were used.
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Nutrient cycling by fish supports relatively more primary production as lake productivity increases.

TL;DR: This study quantified the nutrient cycling role of an abundant detritivorous fish species, the gizzard shad, in reservoir ecosystems along a gradient of ecosystem productivity, and supports the hypothesis that watersheds and gizzardShad jointly regulate primary production in reservoirs ecosystems.
References
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Journal ArticleDOI

Acoustic backscattering cross sections of fish at three frequencies and their representation on a universal graph

TL;DR: In this article, scale-model measurements on small fish are extended to those having lengths L between 4λ and 18λ. This region is found to exhibit many wide fluctuations in the value of the acoustic backscattering cross section.
Journal ArticleDOI

Acoustic Reflexion Experiments With Perch ( Perca Fluviatilis Linn.) to Determine the Proportion of the Echo Returned by the Swimbladder

TL;DR: The amplitude of the echo fell by 50% when the swimbladder was emptied; this was observed both when the dorsal surface and when the lateral surface faced the direction of the incident sound energy.
Journal ArticleDOI

Further measurements of the sound scattering properties of several marine organisms

TL;DR: In this article, the results of fish, squid and large shrimp were analyzed to give the effective scattering area of each over a frequency range of from 8 Kc to 30 Kc, assuming an idealized layer an estimate was made using these values of the number of scatterers of each type necessary to account for the volume reverberation reported for the deep scattering layer.
Journal ArticleDOI

The target strengths of fish

TL;DR: In this article, the acoustic scattering properties of fish have been investigated at different frequencies, initially at the frequencies of existing sonar equipment, but later over a much wider range of frequencies, pursuing a more fundamental approach to understand the formation of fish echoes and their relation to the physical structure of the fish.