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dc.contributor.authorKrafft, Bjørn A.
dc.contributor.authorSkaret, Georg
dc.contributor.authorKnutsen, Tor
dc.contributor.authorMelle, Webjørn
dc.contributor.authorKlevjer, Thor A.
dc.contributor.authorSøiland, Henrik
dc.date.accessioned2012-11-16T18:30:45Z
dc.date.available2012-11-16T18:30:45Z
dc.date.issued2012-09-28
dc.identifier.urihttp://hdl.handle.net/11250/109230
dc.description.abstractKnowledge about swarm dynamics and underlying causes is essential to understand the ecology and distribution of Antarctic krill Euphausia superba. We collected acoustic data and key environmental data continuously across extensive gradients in the little-studied Southeast Atlantic sector of the Southern Ocean. A total of 4791 krill swarms with swarm descriptors including swarm height and length, packing density, swimming depth and inter-swarm distance were extracted. Through multivariate statistics, swarms were categorized into 4 groups. Group 2 swarms were largest (median length 108 m and thickness 18 m), whereas swarms in both Groups 1 and 4 were on average small, but differed markedly in depth distribution (median: 52 m for Group 1 vs. 133 m for Group 4). There was a strong spatial autocorrelation in the occurrence of swarms, and an autologistic regression model found no prediction of swarm occurrence from environmental variables for any of the Groups 1, 2 or 4. Probability of occurrence of Group 3 swarms, however, increased with increasing depth and temperature. Group 3 was the most distinctive swarm group with an order of magnitude higher packing density (median: 226 ind. m−3) than swarms from any of the other groups and about twice the distance to nearest neighbor swarm (median: 493 m). The majority of the krill were present in Group 3 swarms, and the absence of association with hydrographic or topographic concentrating mechanisms strongly suggests that these swarms aggregate through their own locomotion, possibly associated with migration.no_NO
dc.language.isoengno_NO
dc.publisherInter-Researchno_NO
dc.subjectantarctic krillno_NO
dc.subjectkrillno_NO
dc.subjectacousticsno_NO
dc.subjectakustikkno_NO
dc.titleAntarctic krill swarm characteristics in the Southeast Atlantic sector of the Southern Oceanno_NO
dc.typeJournal articleno_NO
dc.typePeer reviewedno_NO
dc.subject.nsiVDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Resource biology: 921no_NO
dc.subject.nsiVDP::Mathematics and natural science: 400::Geosciences: 450::Oceanography: 452no_NO
dc.subject.nsiVDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Fish health: 923no_NO
dc.source.pagenumber69-83no_NO
dc.source.volume465no_NO
dc.source.journalMarine Ecology Progress Seriesno_NO
dc.identifier.doihttp://dx.doi.org/10.3354/meps09876


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