Target strength of the lanternfish, Stenobrachius leucopsarus (family Myctophidae), a fish without an airbladder, measured in the Bering Sea
This paper reports theoretical values of target strength (TS) for the lanternfish Stenobrachius leucopsarus, a fish without an airbladder, which dominates the Subarctic marine mesopelagic fish community. Two models for liquid-like slender bodies, the general prolate-spheroid model (PSM) and the defo...
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Online Access: | http://hdl.handle.net/2115/11325 https://doi.org/10.1016/j.icesjms.2005.02.016 |
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fthokunivhus:oai:eprints.lib.hokudai.ac.jp:2115/11325 2023-05-15T15:43:59+02:00 Target strength of the lanternfish, Stenobrachius leucopsarus (family Myctophidae), a fish without an airbladder, measured in the Bering Sea Yasuma, Hiroki Takao, Yoshimi Sawada, Kouichi Miyashita, Kazushi Aoki, Ichiro http://hdl.handle.net/2115/11325 https://doi.org/10.1016/j.icesjms.2005.02.016 eng eng ACADEMIC PRESS ELSEVIER SCIENCE http://icesjms.oxfordjournals.org/ http://hdl.handle.net/2115/11325 ICES journal of marine science, 63(4): 683-692 http://dx.doi.org/10.1016/j.icesjms.2005.02.016 body-mass density body sound speed deformed-cylinder model spheroid model Stenobrachius leucopsarus target strength 468.8 article (author version) fthokunivhus https://doi.org/10.1016/j.icesjms.2005.02.016 2022-11-18T01:01:17Z This paper reports theoretical values of target strength (TS) for the lanternfish Stenobrachius leucopsarus, a fish without an airbladder, which dominates the Subarctic marine mesopelagic fish community. Two models for liquid-like slender bodies, the general prolate-spheroid model (PSM) and the deformed-cylinder model (DCM), were used to compute the TS of the fish relative to its orientation. The relative mass density g and the sound speed h in seawater were measured and used in both models. To confirm the appropriateness of the models, tethered experimental measurements were carried out at 38 kHz for five specimens. The value of g measured by the density-bottle method was very low (1.002–1.009) compared with that of marine fish in general. The value of h measured by the time-average approach was 1.032–1.039 at the water temperature at which S. leucopsarus is found. TS-fluctuation patterns against fish orientation (the TS pattern) estimated from the DCM and PSM were in good agreement in the area of their main lobes. Both models reproduced the main lobes of the measured TS patterns in near-horizontal orientation (<±20°), and they were considered to be effective in measuring the TS of S. leucopsarus in a horizontal (swimming) position. After these comparative experiments, we computed the TS of 57 fish (27.8–106.9 mm) at 38, 70, 120, and 200 kHz, using the DCM. A plot of body length (in log scale) against TS showed a non-linear relationship at all frequencies. S. leucopsarus had a very low TS (<−85 dB, TScm), suggesting that acoustic assessment would be highly sensitive, especially when the proportion of small fish is high (e.g. L/λ < 2), and an appropriate frequency should be considered that takes into account both the length composition and the depth of occurrence. Article in Journal/Newspaper Bering Sea Subarctic Hokkaido University Collection of Scholarly and Academic Papers (HUSCAP) Bering Sea ICES Journal of Marine Science 63 4 683 692 |
institution |
Open Polar |
collection |
Hokkaido University Collection of Scholarly and Academic Papers (HUSCAP) |
op_collection_id |
fthokunivhus |
language |
English |
topic |
body-mass density body sound speed deformed-cylinder model spheroid model Stenobrachius leucopsarus target strength 468.8 |
spellingShingle |
body-mass density body sound speed deformed-cylinder model spheroid model Stenobrachius leucopsarus target strength 468.8 Yasuma, Hiroki Takao, Yoshimi Sawada, Kouichi Miyashita, Kazushi Aoki, Ichiro Target strength of the lanternfish, Stenobrachius leucopsarus (family Myctophidae), a fish without an airbladder, measured in the Bering Sea |
topic_facet |
body-mass density body sound speed deformed-cylinder model spheroid model Stenobrachius leucopsarus target strength 468.8 |
description |
This paper reports theoretical values of target strength (TS) for the lanternfish Stenobrachius leucopsarus, a fish without an airbladder, which dominates the Subarctic marine mesopelagic fish community. Two models for liquid-like slender bodies, the general prolate-spheroid model (PSM) and the deformed-cylinder model (DCM), were used to compute the TS of the fish relative to its orientation. The relative mass density g and the sound speed h in seawater were measured and used in both models. To confirm the appropriateness of the models, tethered experimental measurements were carried out at 38 kHz for five specimens. The value of g measured by the density-bottle method was very low (1.002–1.009) compared with that of marine fish in general. The value of h measured by the time-average approach was 1.032–1.039 at the water temperature at which S. leucopsarus is found. TS-fluctuation patterns against fish orientation (the TS pattern) estimated from the DCM and PSM were in good agreement in the area of their main lobes. Both models reproduced the main lobes of the measured TS patterns in near-horizontal orientation (<±20°), and they were considered to be effective in measuring the TS of S. leucopsarus in a horizontal (swimming) position. After these comparative experiments, we computed the TS of 57 fish (27.8–106.9 mm) at 38, 70, 120, and 200 kHz, using the DCM. A plot of body length (in log scale) against TS showed a non-linear relationship at all frequencies. S. leucopsarus had a very low TS (<−85 dB, TScm), suggesting that acoustic assessment would be highly sensitive, especially when the proportion of small fish is high (e.g. L/λ < 2), and an appropriate frequency should be considered that takes into account both the length composition and the depth of occurrence. |
format |
Article in Journal/Newspaper |
author |
Yasuma, Hiroki Takao, Yoshimi Sawada, Kouichi Miyashita, Kazushi Aoki, Ichiro |
author_facet |
Yasuma, Hiroki Takao, Yoshimi Sawada, Kouichi Miyashita, Kazushi Aoki, Ichiro |
author_sort |
Yasuma, Hiroki |
title |
Target strength of the lanternfish, Stenobrachius leucopsarus (family Myctophidae), a fish without an airbladder, measured in the Bering Sea |
title_short |
Target strength of the lanternfish, Stenobrachius leucopsarus (family Myctophidae), a fish without an airbladder, measured in the Bering Sea |
title_full |
Target strength of the lanternfish, Stenobrachius leucopsarus (family Myctophidae), a fish without an airbladder, measured in the Bering Sea |
title_fullStr |
Target strength of the lanternfish, Stenobrachius leucopsarus (family Myctophidae), a fish without an airbladder, measured in the Bering Sea |
title_full_unstemmed |
Target strength of the lanternfish, Stenobrachius leucopsarus (family Myctophidae), a fish without an airbladder, measured in the Bering Sea |
title_sort |
target strength of the lanternfish, stenobrachius leucopsarus (family myctophidae), a fish without an airbladder, measured in the bering sea |
publisher |
ACADEMIC PRESS |
url |
http://hdl.handle.net/2115/11325 https://doi.org/10.1016/j.icesjms.2005.02.016 |
geographic |
Bering Sea |
geographic_facet |
Bering Sea |
genre |
Bering Sea Subarctic |
genre_facet |
Bering Sea Subarctic |
op_relation |
http://icesjms.oxfordjournals.org/ http://hdl.handle.net/2115/11325 ICES journal of marine science, 63(4): 683-692 http://dx.doi.org/10.1016/j.icesjms.2005.02.016 |
op_doi |
https://doi.org/10.1016/j.icesjms.2005.02.016 |
container_title |
ICES Journal of Marine Science |
container_volume |
63 |
container_issue |
4 |
container_start_page |
683 |
op_container_end_page |
692 |
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1766378196752662528 |