Behaviour of mackerel schools during summer feeding migration in the Norwegian Sea, as observed from fishing vessel sonars

Abstract In July 2002, two commercial vessels were used to study the distribution of Northeast Atlantic mackerel (Scomber scombrus L.) during their feeding migration in the eastern part of the Norwegian Sea between 62°N and 70°N. Pelagic trawling and school tracking with SIMRAD 24–36 kHz sonar demon...

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Bibliographic Details
Published in:ICES Journal of Marine Science
Main Authors: Godø, Olav Rune, Hjellvik, Vidar, Iversen, Svein A., Slotte, Aril, Tenningen, Eirik, Torkelsen, Terje
Format: Article in Journal/Newspaper
Language:English
Published: Oxford University Press (OUP) 2004
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Online Access:http://dx.doi.org/10.1016/j.icesjms.2004.06.009
http://academic.oup.com/icesjms/article-pdf/61/7/1093/29122469/61-7-1093.pdf
Description
Summary:Abstract In July 2002, two commercial vessels were used to study the distribution of Northeast Atlantic mackerel (Scomber scombrus L.) during their feeding migration in the eastern part of the Norwegian Sea between 62°N and 70°N. Pelagic trawling and school tracking with SIMRAD 24–36 kHz sonar demonstrated that the stock was distributed throughout the study area. Information about time, geographic position, size, depth, speed, and direction was stored for each school during tracking. This study reports analyses of data from 63 schools that were tracked for 30 s or longer. All schools were recorded at depths of less than 100 m, and the majority (65%) were found between the surface and 40 m. The direction of migration (north 0° ± 22.5°, northeast 45° ± 22.5°, etc.) was non-random, with east and west as dominant swimming directions. School size and migration speed varied from 1 to 7000 tonnes and 0 to 6 m s−1, respectively. Methodological improvements are discussed.