Diurnal variation in frequency response of gadoids in the Barents Sea
Earlier studies have demonstrated substantial diurnal variation in acoustic abundance of fish. Both the level and the uncertainty of abundance estimates from surveys carried out around the clock are affected. It has been hypothesized that diurnal variation in acoustic densities is caused by a diurna...
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ftimr:oai:imr.brage.unit.no:11250/100879 2023-05-15T15:38:40+02:00 Diurnal variation in frequency response of gadoids in the Barents Sea Godø, Olav Rune Hjellvik, Vidar Tjøstheim, Dag 2006 3460159 bytes application/pdf http://hdl.handle.net/11250/100879 eng eng ICES ICES CM documents 2006/I:23 http://hdl.handle.net/11250/100879 9 s. cod torsk haddock hyse echo sounder ekkolodd VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Fisheries technology: 924 Working paper 2006 ftimr 2021-09-23T20:15:48Z Earlier studies have demonstrated substantial diurnal variation in acoustic abundance of fish. Both the level and the uncertainty of abundance estimates from surveys carried out around the clock are affected. It has been hypothesized that diurnal variation in acoustic densities is caused by a diurnal variation in tilt angle. As the directivity of fish is higher at higher frequencies a diurnal variation in tilt angle will affect the acoustic recordings more for higher than for lower frequencies. This hypothesis is tested through an analysis of the frequency response of acoustic recordings of cod and haddock in the Barents Sea from 18, 38, 70 and 120 kHz Simrad EK 60 echo sounders. The results demonstrate, as expected, a systematic diurnal change where the reduction in acoustic densities during nighttime is more prominent for higher frequencies. The result is expected since gadoids are visual feeders being active with a more directed swimming pattern at daytime than during night when they have a more relaxed swimming with more variable tilt angle. Applications of the results for improving the quality of survey abundance estimates are discussed. Report Barents Sea Institute for Marine Research: Brage IMR Barents Sea |
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Open Polar |
collection |
Institute for Marine Research: Brage IMR |
op_collection_id |
ftimr |
language |
English |
topic |
cod torsk haddock hyse echo sounder ekkolodd VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Fisheries technology: 924 |
spellingShingle |
cod torsk haddock hyse echo sounder ekkolodd VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Fisheries technology: 924 Godø, Olav Rune Hjellvik, Vidar Tjøstheim, Dag Diurnal variation in frequency response of gadoids in the Barents Sea |
topic_facet |
cod torsk haddock hyse echo sounder ekkolodd VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Fisheries technology: 924 |
description |
Earlier studies have demonstrated substantial diurnal variation in acoustic abundance of fish. Both the level and the uncertainty of abundance estimates from surveys carried out around the clock are affected. It has been hypothesized that diurnal variation in acoustic densities is caused by a diurnal variation in tilt angle. As the directivity of fish is higher at higher frequencies a diurnal variation in tilt angle will affect the acoustic recordings more for higher than for lower frequencies. This hypothesis is tested through an analysis of the frequency response of acoustic recordings of cod and haddock in the Barents Sea from 18, 38, 70 and 120 kHz Simrad EK 60 echo sounders. The results demonstrate, as expected, a systematic diurnal change where the reduction in acoustic densities during nighttime is more prominent for higher frequencies. The result is expected since gadoids are visual feeders being active with a more directed swimming pattern at daytime than during night when they have a more relaxed swimming with more variable tilt angle. Applications of the results for improving the quality of survey abundance estimates are discussed. |
format |
Report |
author |
Godø, Olav Rune Hjellvik, Vidar Tjøstheim, Dag |
author_facet |
Godø, Olav Rune Hjellvik, Vidar Tjøstheim, Dag |
author_sort |
Godø, Olav Rune |
title |
Diurnal variation in frequency response of gadoids in the Barents Sea |
title_short |
Diurnal variation in frequency response of gadoids in the Barents Sea |
title_full |
Diurnal variation in frequency response of gadoids in the Barents Sea |
title_fullStr |
Diurnal variation in frequency response of gadoids in the Barents Sea |
title_full_unstemmed |
Diurnal variation in frequency response of gadoids in the Barents Sea |
title_sort |
diurnal variation in frequency response of gadoids in the barents sea |
publisher |
ICES |
publishDate |
2006 |
url |
http://hdl.handle.net/11250/100879 |
geographic |
Barents Sea |
geographic_facet |
Barents Sea |
genre |
Barents Sea |
genre_facet |
Barents Sea |
op_source |
9 s. |
op_relation |
ICES CM documents 2006/I:23 http://hdl.handle.net/11250/100879 |
_version_ |
1766369893511331840 |