Why is age determination of Baltic cod (Gadus morhua) so difficult?
<qd> Hüssy, K. 2010. Why is age determination of Baltic cod ( Gadus morhua ) so difficult? – ICES Journal of Marine Science, 67: 000–000. </qd>The aim of this study was to evaluate the consistency of three methods for assigning annuli in adult Baltic cod otoliths. The methods examined we...
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fthighwire:oai:open-archive.highwire.org:icesjms:fsq023v1 2023-05-15T16:19:00+02:00 Why is age determination of Baltic cod (Gadus morhua) so difficult? Hüssy, Karin 2010-04-07 04:42:09.0 text/html http://icesjms.oxfordjournals.org/cgi/content/short/fsq023v1 https://doi.org/10.1093/icesjms/fsq023 en eng Oxford University Press http://icesjms.oxfordjournals.org/cgi/content/short/fsq023v1 http://dx.doi.org/10.1093/icesjms/fsq023 Copyright (C) 2010, International Council for the Exploration of the Sea/Conseil International pour l'Exploration de la Mer Article TEXT 2010 fthighwire https://doi.org/10.1093/icesjms/fsq023 2013-05-26T22:46:39Z <qd> Hüssy, K. 2010. Why is age determination of Baltic cod ( Gadus morhua ) so difficult? – ICES Journal of Marine Science, 67: 000–000. </qd>The aim of this study was to evaluate the consistency of three methods for assigning annuli in adult Baltic cod otoliths. The methods examined were (i) daily increment patterns, (ii) opacity profiles, and (iii) traditional age reading. Frequency distributions of the distance from the nucleus to the different zones showed that the first annulus of traditional age reading missed the first zone of both increment and opacity methods, but overlapped with the second zone identified by these methods. This pattern did not continue over subsequent zones. Frequency distributions of increment patterns were similar to opacity patterns. However, within individual fish, the co-occurrence of overlap between the two patterns was random. In cases where there was overlap, translucent zone formation started just before the disappearance of visible increments. Overlap in 1 year did not necessarily lead to a consistent pattern the following year, and overlap was not influenced by sex or fish size. The results suggest that otolith opacity in Baltic cod is not associated with seasonal patterns in daily increment structure and that traditional age determination based on otolith opacity yields highly uncertain estimates of age. Text Gadus morhua HighWire Press (Stanford University) ICES Journal of Marine Science 67 6 1198 1205 |
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Article Hüssy, Karin Why is age determination of Baltic cod (Gadus morhua) so difficult? |
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<qd> Hüssy, K. 2010. Why is age determination of Baltic cod ( Gadus morhua ) so difficult? – ICES Journal of Marine Science, 67: 000–000. </qd>The aim of this study was to evaluate the consistency of three methods for assigning annuli in adult Baltic cod otoliths. The methods examined were (i) daily increment patterns, (ii) opacity profiles, and (iii) traditional age reading. Frequency distributions of the distance from the nucleus to the different zones showed that the first annulus of traditional age reading missed the first zone of both increment and opacity methods, but overlapped with the second zone identified by these methods. This pattern did not continue over subsequent zones. Frequency distributions of increment patterns were similar to opacity patterns. However, within individual fish, the co-occurrence of overlap between the two patterns was random. In cases where there was overlap, translucent zone formation started just before the disappearance of visible increments. Overlap in 1 year did not necessarily lead to a consistent pattern the following year, and overlap was not influenced by sex or fish size. The results suggest that otolith opacity in Baltic cod is not associated with seasonal patterns in daily increment structure and that traditional age determination based on otolith opacity yields highly uncertain estimates of age. |
format |
Text |
author |
Hüssy, Karin |
author_facet |
Hüssy, Karin |
author_sort |
Hüssy, Karin |
title |
Why is age determination of Baltic cod (Gadus morhua) so difficult? |
title_short |
Why is age determination of Baltic cod (Gadus morhua) so difficult? |
title_full |
Why is age determination of Baltic cod (Gadus morhua) so difficult? |
title_fullStr |
Why is age determination of Baltic cod (Gadus morhua) so difficult? |
title_full_unstemmed |
Why is age determination of Baltic cod (Gadus morhua) so difficult? |
title_sort |
why is age determination of baltic cod (gadus morhua) so difficult? |
publisher |
Oxford University Press |
publishDate |
2010 |
url |
http://icesjms.oxfordjournals.org/cgi/content/short/fsq023v1 https://doi.org/10.1093/icesjms/fsq023 |
genre |
Gadus morhua |
genre_facet |
Gadus morhua |
op_relation |
http://icesjms.oxfordjournals.org/cgi/content/short/fsq023v1 http://dx.doi.org/10.1093/icesjms/fsq023 |
op_rights |
Copyright (C) 2010, International Council for the Exploration of the Sea/Conseil International pour l'Exploration de la Mer |
op_doi |
https://doi.org/10.1093/icesjms/fsq023 |
container_title |
ICES Journal of Marine Science |
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67 |
container_issue |
6 |
container_start_page |
1198 |
op_container_end_page |
1205 |
_version_ |
1766005310943657984 |