Multifrequency target strength of northern krill (Meganyctiphanes norvegica) swimming horizontally
<qd> Calise, L., and Knutsen, T. Multifrequency target strength of northern krill ( Meganyctiphanes norvegica ) swimming horizontally. – ICES Journal of Marine Science, doi:10.1093/icesjms/fsr170. </qd>Multifrequency acoustic measurements on ex situ horizontally swimming krill were made...
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fthighwire:oai:open-archive.highwire.org:icesjms:fsr170v1 2023-05-15T17:10:40+02:00 Multifrequency target strength of northern krill (Meganyctiphanes norvegica) swimming horizontally Calise, Lucio Knutsen, Tor 2011-11-01 01:22:30.0 text/html http://icesjms.oxfordjournals.org/cgi/content/short/fsr170v1 https://doi.org/10.1093/icesjms/fsr170 en eng Oxford University Press http://icesjms.oxfordjournals.org/cgi/content/short/fsr170v1 http://dx.doi.org/10.1093/icesjms/fsr170 Copyright (C) 2011, International Council for the Exploration of the Sea/Conseil International pour l'Exploration de la Mer Article TEXT 2011 fthighwire https://doi.org/10.1093/icesjms/fsr170 2013-05-26T22:47:18Z <qd> Calise, L., and Knutsen, T. Multifrequency target strength of northern krill ( Meganyctiphanes norvegica ) swimming horizontally. – ICES Journal of Marine Science, doi:10.1093/icesjms/fsr170. </qd>Multifrequency acoustic measurements on ex situ horizontally swimming krill were made in a novel experimental setting. An ensemble of northern krill ( Meganyctiphanes norvegica ) was introduced to a large enclosure (a mesocosm), and acoustic backscatter was sampled using a multifrequency (70, 120, and 200 kHz) echosounder (Simrad EK60). Two submerged lamps were placed at opposite sides of the mesocosm and switched on and off to induce the krill, by light attraction, to swim horizontally through the acoustic beams. By tracking echoes, animal displacement, swimming speed, and target strength ( TS ) by frequency were estimated. The dominant and secondary modes of the total-length distribution were 21.8 ± 3.0 and 27.8 ± 2.7 mm, respectively. Although krill orientation was assumed stable and the ping rate was high, the range and inter-ping variability of the average TS values were large, decreasing and increasing with frequency, respectively. The overall TS frequency response observed and concurrent measurements at 120 and 200 kHz confirm the theoretical expectation that the acoustic backscatter from the investigated organisms were confined to the Rayleigh and Geometric scattering regions, a finding that might both aid acoustic identification and size-group separation of in situ northern krill. Text Meganyctiphanes norvegica Northern krill HighWire Press (Stanford University) ICES Journal of Marine Science 69 1 119 130 |
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English |
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Article Calise, Lucio Knutsen, Tor Multifrequency target strength of northern krill (Meganyctiphanes norvegica) swimming horizontally |
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description |
<qd> Calise, L., and Knutsen, T. Multifrequency target strength of northern krill ( Meganyctiphanes norvegica ) swimming horizontally. – ICES Journal of Marine Science, doi:10.1093/icesjms/fsr170. </qd>Multifrequency acoustic measurements on ex situ horizontally swimming krill were made in a novel experimental setting. An ensemble of northern krill ( Meganyctiphanes norvegica ) was introduced to a large enclosure (a mesocosm), and acoustic backscatter was sampled using a multifrequency (70, 120, and 200 kHz) echosounder (Simrad EK60). Two submerged lamps were placed at opposite sides of the mesocosm and switched on and off to induce the krill, by light attraction, to swim horizontally through the acoustic beams. By tracking echoes, animal displacement, swimming speed, and target strength ( TS ) by frequency were estimated. The dominant and secondary modes of the total-length distribution were 21.8 ± 3.0 and 27.8 ± 2.7 mm, respectively. Although krill orientation was assumed stable and the ping rate was high, the range and inter-ping variability of the average TS values were large, decreasing and increasing with frequency, respectively. The overall TS frequency response observed and concurrent measurements at 120 and 200 kHz confirm the theoretical expectation that the acoustic backscatter from the investigated organisms were confined to the Rayleigh and Geometric scattering regions, a finding that might both aid acoustic identification and size-group separation of in situ northern krill. |
format |
Text |
author |
Calise, Lucio Knutsen, Tor |
author_facet |
Calise, Lucio Knutsen, Tor |
author_sort |
Calise, Lucio |
title |
Multifrequency target strength of northern krill (Meganyctiphanes norvegica) swimming horizontally |
title_short |
Multifrequency target strength of northern krill (Meganyctiphanes norvegica) swimming horizontally |
title_full |
Multifrequency target strength of northern krill (Meganyctiphanes norvegica) swimming horizontally |
title_fullStr |
Multifrequency target strength of northern krill (Meganyctiphanes norvegica) swimming horizontally |
title_full_unstemmed |
Multifrequency target strength of northern krill (Meganyctiphanes norvegica) swimming horizontally |
title_sort |
multifrequency target strength of northern krill (meganyctiphanes norvegica) swimming horizontally |
publisher |
Oxford University Press |
publishDate |
2011 |
url |
http://icesjms.oxfordjournals.org/cgi/content/short/fsr170v1 https://doi.org/10.1093/icesjms/fsr170 |
genre |
Meganyctiphanes norvegica Northern krill |
genre_facet |
Meganyctiphanes norvegica Northern krill |
op_relation |
http://icesjms.oxfordjournals.org/cgi/content/short/fsr170v1 http://dx.doi.org/10.1093/icesjms/fsr170 |
op_rights |
Copyright (C) 2011, International Council for the Exploration of the Sea/Conseil International pour l'Exploration de la Mer |
op_doi |
https://doi.org/10.1093/icesjms/fsr170 |
container_title |
ICES Journal of Marine Science |
container_volume |
69 |
container_issue |
1 |
container_start_page |
119 |
op_container_end_page |
130 |
_version_ |
1766067315429867520 |