Extensive gas bubble release in Norwegian spring spawning herring (Clupea harengus) during predator avoidance
Events of extensive gas bubble releases in overwintering Norwegian spring spawning herring (Clupea harengus) were repeatedly observed acoustically and visually in Vestfjorden, northem Norway, during attacks from killer whales (Orcinus orca) and saithe (Pollachius virens). Gas bubble production was s...
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ftimr:oai:imr.brage.unit.no:11250/105853 2023-05-15T17:03:38+02:00 Extensive gas bubble release in Norwegian spring spawning herring (Clupea harengus) during predator avoidance Nøttestad, Leif 1998 application/pdf http://hdl.handle.net/11250/105853 eng eng ICES ICES CM Documents;1998/J:20 This report is not to be cited without prior reference to the author http://hdl.handle.net/11250/105853 24 s. herring sild killer whale spekkhogger fish behaviour fiskeatferd VDP::Mathematics and natural science: 400::Zoology and botany: 480::Ethology: 485 VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Fish health: 923 VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Resource biology: 921 Working paper 1998 ftimr 2021-09-23T20:15:09Z Events of extensive gas bubble releases in overwintering Norwegian spring spawning herring (Clupea harengus) were repeatedly observed acoustically and visually in Vestfjorden, northem Norway, during attacks from killer whales (Orcinus orca) and saithe (Pollachius virens). Gas bubble production was so extensive that large areas of the sea surface were sometimes covered with white foam after an event. Gas bubbles were visually observed to come from the swimbladder of individual herring swimming very close to the surface. Acoustically, gas bubbles could be identified on the echosounder as strong echoes covering the upper 0-30 m of the water column. Schools of herring were forced from 30-100 m depth up to the surface by predatory killer whales and saithe. I suggest that herring expel gas near the surface as a concequence of the rapid change in depth, and that gas bubble release may confuse and deflect both visually and acoustically oriented predators due to increased scattering of light, reduced range of vision, and confusing effects of the reflection energy of the bubbles and the fish. Such events may have considerable effect on the target strength and estimated stock sizes during acoustic surveys. Report Killer Whale Orca Orcinus orca spekkhogger Vestfjorden Killer whale Institute for Marine Research: Brage IMR Norway |
institution |
Open Polar |
collection |
Institute for Marine Research: Brage IMR |
op_collection_id |
ftimr |
language |
English |
topic |
herring sild killer whale spekkhogger fish behaviour fiskeatferd VDP::Mathematics and natural science: 400::Zoology and botany: 480::Ethology: 485 VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Fish health: 923 VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Resource biology: 921 |
spellingShingle |
herring sild killer whale spekkhogger fish behaviour fiskeatferd VDP::Mathematics and natural science: 400::Zoology and botany: 480::Ethology: 485 VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Fish health: 923 VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Resource biology: 921 Nøttestad, Leif Extensive gas bubble release in Norwegian spring spawning herring (Clupea harengus) during predator avoidance |
topic_facet |
herring sild killer whale spekkhogger fish behaviour fiskeatferd VDP::Mathematics and natural science: 400::Zoology and botany: 480::Ethology: 485 VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Fish health: 923 VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Resource biology: 921 |
description |
Events of extensive gas bubble releases in overwintering Norwegian spring spawning herring (Clupea harengus) were repeatedly observed acoustically and visually in Vestfjorden, northem Norway, during attacks from killer whales (Orcinus orca) and saithe (Pollachius virens). Gas bubble production was so extensive that large areas of the sea surface were sometimes covered with white foam after an event. Gas bubbles were visually observed to come from the swimbladder of individual herring swimming very close to the surface. Acoustically, gas bubbles could be identified on the echosounder as strong echoes covering the upper 0-30 m of the water column. Schools of herring were forced from 30-100 m depth up to the surface by predatory killer whales and saithe. I suggest that herring expel gas near the surface as a concequence of the rapid change in depth, and that gas bubble release may confuse and deflect both visually and acoustically oriented predators due to increased scattering of light, reduced range of vision, and confusing effects of the reflection energy of the bubbles and the fish. Such events may have considerable effect on the target strength and estimated stock sizes during acoustic surveys. |
format |
Report |
author |
Nøttestad, Leif |
author_facet |
Nøttestad, Leif |
author_sort |
Nøttestad, Leif |
title |
Extensive gas bubble release in Norwegian spring spawning herring (Clupea harengus) during predator avoidance |
title_short |
Extensive gas bubble release in Norwegian spring spawning herring (Clupea harengus) during predator avoidance |
title_full |
Extensive gas bubble release in Norwegian spring spawning herring (Clupea harengus) during predator avoidance |
title_fullStr |
Extensive gas bubble release in Norwegian spring spawning herring (Clupea harengus) during predator avoidance |
title_full_unstemmed |
Extensive gas bubble release in Norwegian spring spawning herring (Clupea harengus) during predator avoidance |
title_sort |
extensive gas bubble release in norwegian spring spawning herring (clupea harengus) during predator avoidance |
publisher |
ICES |
publishDate |
1998 |
url |
http://hdl.handle.net/11250/105853 |
geographic |
Norway |
geographic_facet |
Norway |
genre |
Killer Whale Orca Orcinus orca spekkhogger Vestfjorden Killer whale |
genre_facet |
Killer Whale Orca Orcinus orca spekkhogger Vestfjorden Killer whale |
op_source |
24 s. |
op_relation |
ICES CM Documents;1998/J:20 This report is not to be cited without prior reference to the author http://hdl.handle.net/11250/105853 |
_version_ |
1766057534926356480 |