Hydroacoustic ex situ target strength measurements on juvenile cod (Gadus morhua L.)
Most TS-measurements on fish have been carried out for 38 kHz, and the existing TS algorithm for 120 kHz on cod is based on measurements on stunned fish. The main objective of these experiments was to establish an empirical estimate of the relation between acoustic reflection (target strength, TS) a...
Published in: | ICES Journal of Marine Science |
---|---|
Main Authors: | , |
Format: | Text |
Language: | English |
Published: |
Oxford University Press
1999
|
Subjects: | |
Online Access: | http://icesjms.oxfordjournals.org/cgi/content/short/56/5/627 https://doi.org/10.1006/jmsc.1999.0515 |
id |
fthighwire:oai:open-archive.highwire.org:icesjms:56/5/627 |
---|---|
record_format |
openpolar |
spelling |
fthighwire:oai:open-archive.highwire.org:icesjms:56/5/627 2023-05-15T16:19:20+02:00 Hydroacoustic ex situ target strength measurements on juvenile cod (Gadus morhua L.) Nielsen, J. Rasmus Lundgren, Bo 1999-10-01 00:00:00.0 text/html http://icesjms.oxfordjournals.org/cgi/content/short/56/5/627 https://doi.org/10.1006/jmsc.1999.0515 en eng Oxford University Press http://icesjms.oxfordjournals.org/cgi/content/short/56/5/627 http://dx.doi.org/10.1006/jmsc.1999.0515 Copyright (C) 1999, International Council for the Exploration of the Sea/Conseil International pour l'Exploration de la Mer Articles TEXT 1999 fthighwire https://doi.org/10.1006/jmsc.1999.0515 2013-05-27T05:24:57Z Most TS-measurements on fish have been carried out for 38 kHz, and the existing TS algorithm for 120 kHz on cod is based on measurements on stunned fish. The main objective of these experiments was to establish an empirical estimate of the relation between acoustic reflection (target strength, TS) and length of live juvenile cod (7–10 cm and 15–20 cm) at 120 kHz. This was done by recording the variation in TS of freely swimming cod tracking single fish targets for the two size groups within the acoustic beam field. The experiment was set up in an open air 2000 m3 tank where the small 5–10 cm long fish were swimming freely during measurement in cages (1×1×3 m) within the acoustic beam under natural conditions in seawater with a salinity of 30 and a temperature of 11°C. An EY500 split-beam acoustic system was used to detect single fish passing through the acoustic beam field, which was video recorded in order to isolate the measurements on single targets and to get an indication of their angle. A mean target strength-to-size relation was calculated for small cod based on single fish tracks with total acoustic angles below 3.5° off axis in the beam field. This relationship is compared to other TS measurements on juvenile cod in literature. TS at 120 kHz for the investigated cod size range seems to decrease faster by length than the 20 logL relation used for larger cod. The results were used to check the expected range limits of TS for juvenile cod during survey, and are expected to be taken into consideration in density estimation of juvenile cod during acoustic surveys targeting young gadoids in general. Text Gadus morhua HighWire Press (Stanford University) ICES Journal of Marine Science 56 5 627 639 |
institution |
Open Polar |
collection |
HighWire Press (Stanford University) |
op_collection_id |
fthighwire |
language |
English |
topic |
Articles |
spellingShingle |
Articles Nielsen, J. Rasmus Lundgren, Bo Hydroacoustic ex situ target strength measurements on juvenile cod (Gadus morhua L.) |
topic_facet |
Articles |
description |
Most TS-measurements on fish have been carried out for 38 kHz, and the existing TS algorithm for 120 kHz on cod is based on measurements on stunned fish. The main objective of these experiments was to establish an empirical estimate of the relation between acoustic reflection (target strength, TS) and length of live juvenile cod (7–10 cm and 15–20 cm) at 120 kHz. This was done by recording the variation in TS of freely swimming cod tracking single fish targets for the two size groups within the acoustic beam field. The experiment was set up in an open air 2000 m3 tank where the small 5–10 cm long fish were swimming freely during measurement in cages (1×1×3 m) within the acoustic beam under natural conditions in seawater with a salinity of 30 and a temperature of 11°C. An EY500 split-beam acoustic system was used to detect single fish passing through the acoustic beam field, which was video recorded in order to isolate the measurements on single targets and to get an indication of their angle. A mean target strength-to-size relation was calculated for small cod based on single fish tracks with total acoustic angles below 3.5° off axis in the beam field. This relationship is compared to other TS measurements on juvenile cod in literature. TS at 120 kHz for the investigated cod size range seems to decrease faster by length than the 20 logL relation used for larger cod. The results were used to check the expected range limits of TS for juvenile cod during survey, and are expected to be taken into consideration in density estimation of juvenile cod during acoustic surveys targeting young gadoids in general. |
format |
Text |
author |
Nielsen, J. Rasmus Lundgren, Bo |
author_facet |
Nielsen, J. Rasmus Lundgren, Bo |
author_sort |
Nielsen, J. Rasmus |
title |
Hydroacoustic ex situ target strength measurements on juvenile cod (Gadus morhua L.) |
title_short |
Hydroacoustic ex situ target strength measurements on juvenile cod (Gadus morhua L.) |
title_full |
Hydroacoustic ex situ target strength measurements on juvenile cod (Gadus morhua L.) |
title_fullStr |
Hydroacoustic ex situ target strength measurements on juvenile cod (Gadus morhua L.) |
title_full_unstemmed |
Hydroacoustic ex situ target strength measurements on juvenile cod (Gadus morhua L.) |
title_sort |
hydroacoustic ex situ target strength measurements on juvenile cod (gadus morhua l.) |
publisher |
Oxford University Press |
publishDate |
1999 |
url |
http://icesjms.oxfordjournals.org/cgi/content/short/56/5/627 https://doi.org/10.1006/jmsc.1999.0515 |
genre |
Gadus morhua |
genre_facet |
Gadus morhua |
op_relation |
http://icesjms.oxfordjournals.org/cgi/content/short/56/5/627 http://dx.doi.org/10.1006/jmsc.1999.0515 |
op_rights |
Copyright (C) 1999, International Council for the Exploration of the Sea/Conseil International pour l'Exploration de la Mer |
op_doi |
https://doi.org/10.1006/jmsc.1999.0515 |
container_title |
ICES Journal of Marine Science |
container_volume |
56 |
container_issue |
5 |
container_start_page |
627 |
op_container_end_page |
639 |
_version_ |
1766005719638736896 |