Target strengths of Antarctic krill (Euphausia superba) at 38 and 120 kHz
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 . M...
Published in: | The Journal of the Acoustical Society of America |
---|---|
Main Authors: | , , , |
Format: | Article in Journal/Newspaper |
Language: | unknown |
Published: |
Acoustical Society of America
1990
|
Subjects: | |
Online Access: | http://nora.nerc.ac.uk/id/eprint/520396/ https://doi.org/10.1121/1.399282 |
id |
ftnerc:oai:nora.nerc.ac.uk:520396 |
---|---|
record_format |
openpolar |
spelling |
ftnerc:oai:nora.nerc.ac.uk:520396 2023-05-15T13:49:35+02:00 Target strengths of Antarctic krill (Euphausia superba) at 38 and 120 kHz Foote, Kenneth G. Everson, Inigo Watkins, Jonathan L. Bone, Douglas G. 1990 http://nora.nerc.ac.uk/id/eprint/520396/ https://doi.org/10.1121/1.399282 unknown Acoustical Society of America Foote, Kenneth G.; Everson, Inigo; Watkins, Jonathan L.; Bone, Douglas G. 1990 Target strengths of Antarctic krill (Euphausia superba) at 38 and 120 kHz. The Journal of the Acoustical Society of America, 87 (1). 16-24. https://doi.org/10.1121/1.399282 <https://doi.org/10.1121/1.399282> Publication - Article PeerReviewed 1990 ftnerc https://doi.org/10.1121/1.399282 2023-02-04T19:46:43Z 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 Natural Environment Research Council: NERC Open Research Archive Antarctic The Journal of the Acoustical Society of America 87 1 16 24 |
institution |
Open Polar |
collection |
Natural Environment Research Council: NERC Open Research Archive |
op_collection_id |
ftnerc |
language |
unknown |
description |
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. |
spellingShingle |
Foote, Kenneth G. Everson, Inigo Watkins, Jonathan L. Bone, Douglas G. Target strengths of Antarctic krill (Euphausia superba) at 38 and 120 kHz |
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 |
publisher |
Acoustical Society of America |
publishDate |
1990 |
url |
http://nora.nerc.ac.uk/id/eprint/520396/ https://doi.org/10.1121/1.399282 |
geographic |
Antarctic |
geographic_facet |
Antarctic |
genre |
Antarc* Antarctic Antarctic Krill Euphausia superba |
genre_facet |
Antarc* Antarctic Antarctic Krill Euphausia superba |
op_relation |
Foote, Kenneth G.; Everson, Inigo; Watkins, Jonathan L.; Bone, Douglas G. 1990 Target strengths of Antarctic krill (Euphausia superba) at 38 and 120 kHz. The Journal of the Acoustical Society of America, 87 (1). 16-24. https://doi.org/10.1121/1.399282 <https://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_ |
1766251788792496128 |