Journal Article

Life under pressure: insights from electronic data-storage tags into cod swimbladder function

Jeroen van der Kooij, David Righton, Espen Strand, Kathrine Michalsen, Vilhjalmur Thorsteinsson, Henrik Svedäng, Francis C. Neat and Stefan Neuenfeldt

in ICES Journal of Marine Science

Published on behalf of ICES/CIEM

Volume 64, issue 7, pages 1293-1301
Published in print October 2007 | ISSN: 1054-3139
Published online August 2007 | e-ISSN: 1095-9289 | DOI: http://dx.doi.org/10.1093/icesjms/fsm119
Life under pressure: insights from electronic data-storage tags into cod swimbladder function

More Like This

Show all results sharing these subjects:

  • Environmental Science
  • Marine and Estuarine Biology

GO

Show Summary Details

Preview

van der Kooij, J., Righton, D., Strand, E., Michalsen, K., Thorsteinsson, V., Svedäng, H., Neat, F. C., and Neuenfeldt, S. 2007. Life under pressure: insights from electronic data-storage tags into cod swimbladder function. – ICES Journal of Marine Science. 64: 1293–1301.

The behavioural response of cod (Gadus morhua) to sudden pressure reductions was investigated in a large electronic-tagging experiment using data collected from 141 cod tagged in five different areas of the Northeast Atlantic. More than 40% of cod exhibited a characteristic equilibration behaviour after a rapid pressure reduction caused either by capture before tagging, or by pressure reduction during a rapid ascent from the seabed, or when migrating to deeper water. The equilibration allowed the cod to regain demersal residence. The rate of descent averaged 10 m d−1 (ranging from 2 to 23 m d−1) over periods of less than a day to 1 month. Descent rates for cod on the Icelandic shelf were inversely related to fish length, i.e. smaller fish descended more rapidly, findings consistent with results achieved in the past under laboratory conditions. Modelling of swimbladder volume during equilibration suggested that cod were negatively buoyant for most of the time. The results imply that swimbladder functionality is retained after the probable barotrauma that would follow a large and rapid ascent, and that rates of gas exchange into the swimbladder may be naturally variable. These findings have implications for assumptions on discard mortality, the interpretation of cod behaviour, and its impact on biomass estimates obtained from acoustic surveys.

Keywords: behaviour; buoyancy; cod; discard; physoclists

Journal Article.  6230 words.  Illustrated.

Subjects: Environmental Science ; Marine and Estuarine Biology

Full text: subscription required

How to subscribe Recommend to my Librarian

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.