Age and growth estimates of bowhead whales ( Balaena mysticetus) via aspartic acid racemization
A total of 48 eye globes were collected and analyzed to estimate ages of bowhead whales using the aspartic acid racemization technique. In this technique, age is estimated based on intrinsic changes in the D and L enantiomeric isomeric forms of aspartic acid in the eye lens nucleus. Age estimates we...
Published in: | Canadian Journal of Zoology |
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1999
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crcansciencepubl:10.1139/z99-015 2024-09-30T14:32:41+00:00 Age and growth estimates of bowhead whales ( Balaena mysticetus) via aspartic acid racemization George, John C Bada, Jeffrey Zeh, Judith Scott, Laura Brown, Stephen E O'Hara, Todd Suydam, Robert 1999 http://dx.doi.org/10.1139/z99-015 http://www.nrcresearchpress.com/doi/pdf/10.1139/z99-015 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Zoology volume 77, issue 4, page 571-580 ISSN 0008-4301 1480-3283 journal-article 1999 crcansciencepubl https://doi.org/10.1139/z99-015 2024-09-12T04:13:27Z A total of 48 eye globes were collected and analyzed to estimate ages of bowhead whales using the aspartic acid racemization technique. In this technique, age is estimated based on intrinsic changes in the D and L enantiomeric isomeric forms of aspartic acid in the eye lens nucleus. Age estimates were successful for 42 animals. Racemization rate (k Asp ) for aspartic acid was based on data from earlier studies of humans and fin whales; the estimate used was 1.18 10 -3 /year. The D/L ratio at birth ((D/L) 0 ) was estimated using animals less than or equal to 2 years of age (n = 8), since variability in the D/L measurements is large enough that differences among ages in this range are unmeasurable. The (D/L) 0 estimate was 0.0285. Variance of the age estimates was obtained using the delta method. Based on these data, growth appears faster for females than males, and age at sexual maturity (age at length 12-13 m for males and 13-13.5 m for females) occurs at around 25 years of age. Growth slows markedly for both sexes at roughly 40-50 years of age. Four individuals (all males) exceed 100 years of age. Standard error increased with estimated age, but the age estimates had lower coefficients of variation for older animals. Recoveries of traditional whale-hunting tools from five recently harvested whales also suggest life-spans in excess of 100 years of age in some cases. Article in Journal/Newspaper Balaena mysticetus Canadian Science Publishing Canadian Journal of Zoology 77 4 571 580 |
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Open Polar |
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Canadian Science Publishing |
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crcansciencepubl |
language |
English |
description |
A total of 48 eye globes were collected and analyzed to estimate ages of bowhead whales using the aspartic acid racemization technique. In this technique, age is estimated based on intrinsic changes in the D and L enantiomeric isomeric forms of aspartic acid in the eye lens nucleus. Age estimates were successful for 42 animals. Racemization rate (k Asp ) for aspartic acid was based on data from earlier studies of humans and fin whales; the estimate used was 1.18 10 -3 /year. The D/L ratio at birth ((D/L) 0 ) was estimated using animals less than or equal to 2 years of age (n = 8), since variability in the D/L measurements is large enough that differences among ages in this range are unmeasurable. The (D/L) 0 estimate was 0.0285. Variance of the age estimates was obtained using the delta method. Based on these data, growth appears faster for females than males, and age at sexual maturity (age at length 12-13 m for males and 13-13.5 m for females) occurs at around 25 years of age. Growth slows markedly for both sexes at roughly 40-50 years of age. Four individuals (all males) exceed 100 years of age. Standard error increased with estimated age, but the age estimates had lower coefficients of variation for older animals. Recoveries of traditional whale-hunting tools from five recently harvested whales also suggest life-spans in excess of 100 years of age in some cases. |
format |
Article in Journal/Newspaper |
author |
George, John C Bada, Jeffrey Zeh, Judith Scott, Laura Brown, Stephen E O'Hara, Todd Suydam, Robert |
spellingShingle |
George, John C Bada, Jeffrey Zeh, Judith Scott, Laura Brown, Stephen E O'Hara, Todd Suydam, Robert Age and growth estimates of bowhead whales ( Balaena mysticetus) via aspartic acid racemization |
author_facet |
George, John C Bada, Jeffrey Zeh, Judith Scott, Laura Brown, Stephen E O'Hara, Todd Suydam, Robert |
author_sort |
George, John C |
title |
Age and growth estimates of bowhead whales ( Balaena mysticetus) via aspartic acid racemization |
title_short |
Age and growth estimates of bowhead whales ( Balaena mysticetus) via aspartic acid racemization |
title_full |
Age and growth estimates of bowhead whales ( Balaena mysticetus) via aspartic acid racemization |
title_fullStr |
Age and growth estimates of bowhead whales ( Balaena mysticetus) via aspartic acid racemization |
title_full_unstemmed |
Age and growth estimates of bowhead whales ( Balaena mysticetus) via aspartic acid racemization |
title_sort |
age and growth estimates of bowhead whales ( balaena mysticetus) via aspartic acid racemization |
publisher |
Canadian Science Publishing |
publishDate |
1999 |
url |
http://dx.doi.org/10.1139/z99-015 http://www.nrcresearchpress.com/doi/pdf/10.1139/z99-015 |
genre |
Balaena mysticetus |
genre_facet |
Balaena mysticetus |
op_source |
Canadian Journal of Zoology volume 77, issue 4, page 571-580 ISSN 0008-4301 1480-3283 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/z99-015 |
container_title |
Canadian Journal of Zoology |
container_volume |
77 |
container_issue |
4 |
container_start_page |
571 |
op_container_end_page |
580 |
_version_ |
1811636767178096640 |