Target strengths of Antarctic krill (Euphausia superba) at 38 and 120 kHz
Journal home page: http://scitation.aip.org/jasa/ Encaged aggregations of live krill in good to pristine condition have been ensonified at 38 and 120 kHz. Concurrent underwater television observations of behavior resemble those made by underwater divers in naturally occurring swarms, with comparably...
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1990
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Online Access: | http://hdl.handle.net/11250/108164 https://doi.org/10.1121/1.399282 |
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ftimr:oai:imr.brage.unit.no:11250/108164 2024-09-15T17:48:38+00:00 Target strengths of Antarctic krill (Euphausia superba) at 38 and 120 kHz Foote, Kenneth G. Everson, Inigo Watkins, Jonathan L. Bone, Douglas G. 1990 863122 bytes application/pdf http://hdl.handle.net/11250/108164 https://doi.org/10.1121/1.399282 eng eng http://hdl.handle.net/11250/108164 http://dx.doi.org/10.1121/1.399282 16-24 87 The Journal of the Acoustical Society of America 1 krill Journal article Peer reviewed 1990 ftimr https://doi.org/10.1121/1.399282 2024-07-31T03:37:25Z Journal home page: http://scitation.aip.org/jasa/ Encaged aggregations of live krill in good to pristine condition have been ensonified at 38 and 120 kHz. Concurrent underwater television observations of behavior resemble those made by underwater divers in naturally occurring swarms, with comparably high densities of the order of 104 animals/m3 . Mean, single-animal target strengths have been inferred from measurements of echo energy. For aggregations with mean lengths in the range [30,39] mm, the mean single-krill target strengths are in the range [–88,–83] dB at 38 kHz and [–81,–74] dB at 120 kHz. Collateral measurements on some of the same encaged specimens determined a density contrast of 1.0357±0.0067 and sound-speed contrast of 1.0279±0.0024, relative to seawater. These numbers have been used with the fluid-sphere model as stated by Greenlaw [Limnol. Oceanogr. 24, 226–242 (1979)] . Computed backscattering cross sections have been averaged over the length distributions of each measured aggregation, resulting in target strength predictions in the range [–86,–80] dB at 38 kHz and [–79,–76] dB at 120 kHz. Article in Journal/Newspaper Antarc* Antarctic Antarctic Krill Euphausia superba Institute for Marine Research: Brage IMR The Journal of the Acoustical Society of America 87 1 16 24 |
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Open Polar |
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Institute for Marine Research: Brage IMR |
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ftimr |
language |
English |
topic |
krill |
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krill Foote, Kenneth G. Everson, Inigo Watkins, Jonathan L. Bone, Douglas G. Target strengths of Antarctic krill (Euphausia superba) at 38 and 120 kHz |
topic_facet |
krill |
description |
Journal home page: http://scitation.aip.org/jasa/ Encaged aggregations of live krill in good to pristine condition have been ensonified at 38 and 120 kHz. Concurrent underwater television observations of behavior resemble those made by underwater divers in naturally occurring swarms, with comparably high densities of the order of 104 animals/m3 . Mean, single-animal target strengths have been inferred from measurements of echo energy. For aggregations with mean lengths in the range [30,39] mm, the mean single-krill target strengths are in the range [–88,–83] dB at 38 kHz and [–81,–74] dB at 120 kHz. Collateral measurements on some of the same encaged specimens determined a density contrast of 1.0357±0.0067 and sound-speed contrast of 1.0279±0.0024, relative to seawater. These numbers have been used with the fluid-sphere model as stated by Greenlaw [Limnol. Oceanogr. 24, 226–242 (1979)] . Computed backscattering cross sections have been averaged over the length distributions of each measured aggregation, resulting in target strength predictions in the range [–86,–80] dB at 38 kHz and [–79,–76] dB at 120 kHz. |
format |
Article in Journal/Newspaper |
author |
Foote, Kenneth G. Everson, Inigo Watkins, Jonathan L. Bone, Douglas G. |
author_facet |
Foote, Kenneth G. Everson, Inigo Watkins, Jonathan L. Bone, Douglas G. |
author_sort |
Foote, Kenneth G. |
title |
Target strengths of Antarctic krill (Euphausia superba) at 38 and 120 kHz |
title_short |
Target strengths of Antarctic krill (Euphausia superba) at 38 and 120 kHz |
title_full |
Target strengths of Antarctic krill (Euphausia superba) at 38 and 120 kHz |
title_fullStr |
Target strengths of Antarctic krill (Euphausia superba) at 38 and 120 kHz |
title_full_unstemmed |
Target strengths of Antarctic krill (Euphausia superba) at 38 and 120 kHz |
title_sort |
target strengths of antarctic krill (euphausia superba) at 38 and 120 khz |
publishDate |
1990 |
url |
http://hdl.handle.net/11250/108164 https://doi.org/10.1121/1.399282 |
genre |
Antarc* Antarctic Antarctic Krill Euphausia superba |
genre_facet |
Antarc* Antarctic Antarctic Krill Euphausia superba |
op_source |
16-24 87 The Journal of the Acoustical Society of America 1 |
op_relation |
http://hdl.handle.net/11250/108164 http://dx.doi.org/10.1121/1.399282 |
op_doi |
https://doi.org/10.1121/1.399282 |
container_title |
The Journal of the Acoustical Society of America |
container_volume |
87 |
container_issue |
1 |
container_start_page |
16 |
op_container_end_page |
24 |
_version_ |
1810290084286562304 |