A New Simple Method for Age Determination of Harbour Porpoises (Phocoena phocoena)
Age determination of marine mammals is important for understanding the impact of anthropogenic disturbances as well as for population management. Toothed whales are usually age-determined by counting annually formed layers in their teeth. This includes a time-consuming sequence of preparations, usua...
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2024
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Online Access: | https://portal.findresearcher.sdu.dk/da/publications/d265ff8a-f827-4a69-aea4-b7ec044cb08e https://doi.org/10.1578/AM.50.1.2024.30 |
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ftsydanskunivpub:oai:sdu.dk:publications/d265ff8a-f827-4a69-aea4-b7ec044cb08e 2024-05-19T07:47:22+00:00 A New Simple Method for Age Determination of Harbour Porpoises (Phocoena phocoena) Henriksen, Louise B. Thøstesen, Charlotte Bie Alstrup, Aage Kristian Olsen Larsen, Hanne Lyngholm Wahlberg, Magnus Siebert, Ursula Pagh, Sussie 2024 https://portal.findresearcher.sdu.dk/da/publications/d265ff8a-f827-4a69-aea4-b7ec044cb08e https://doi.org/10.1578/AM.50.1.2024.30 eng eng https://portal.findresearcher.sdu.dk/da/publications/d265ff8a-f827-4a69-aea4-b7ec044cb08e info:eu-repo/semantics/closedAccess Henriksen , L B , Thøstesen , C B , Alstrup , A K O , Larsen , H L , Wahlberg , M , Siebert , U & Pagh , S 2024 , ' A New Simple Method for Age Determination of Harbour Porpoises (Phocoena phocoena) ' , Aquatic Mammals , vol. 50 , no. 1 , pp. 30-38 . https://doi.org/10.1578/AM.50.1.2024.30 age methodology counting growth layers demography grinding teeth mortality toothed whale article 2024 ftsydanskunivpub https://doi.org/10.1578/AM.50.1.2024.30 2024-04-24T00:51:26Z Age determination of marine mammals is important for understanding the impact of anthropogenic disturbances as well as for population management. Toothed whales are usually age-determined by counting annually formed layers in their teeth. This includes a time-consuming sequence of preparations, usually involving chemical treatment. This study tested a quicker and simpler method for age determination of harbour porpoises (Phocoena phocoena), originally developed for age determination of foxes and other terrestrial carnivores. The tooth was ground with fine-grained sandpaper, and the age lines were directly read using a binocular microscope. To evaluate the usability of the grinding method for harbour porpoises, three tests were used: (1) the number of growth layer groups (GLGs) in teeth from 66 harbour porpoises by the grinding method were compared by two readers; (2) GLGs in teeth from six harbour porpoises prepared by the grinding method and by the decalcification method were compared in a blinded set-up with two readers; and (3) the GLGs in teeth from two individuals with known ages prepared by both the grinding method and the decalcification method, respectively, were compared. A Bland–Altman plot showed high agreement between the determined age of individuals by the two different methods. The average age difference was -0.56 years, and the 95% confidence interval for the average difference was [-4.3, 3.2] years. The grinding method is therefore considered to be a valid alternative and quicker method for age determination of harbour porpoises. Article in Journal/Newspaper Phocoena phocoena toothed whale toothed whales University of Southern Denmark Research Portal Aquatic Mammals 50 1 30 38 |
institution |
Open Polar |
collection |
University of Southern Denmark Research Portal |
op_collection_id |
ftsydanskunivpub |
language |
English |
topic |
age methodology counting growth layers demography grinding teeth mortality toothed whale |
spellingShingle |
age methodology counting growth layers demography grinding teeth mortality toothed whale Henriksen, Louise B. Thøstesen, Charlotte Bie Alstrup, Aage Kristian Olsen Larsen, Hanne Lyngholm Wahlberg, Magnus Siebert, Ursula Pagh, Sussie A New Simple Method for Age Determination of Harbour Porpoises (Phocoena phocoena) |
topic_facet |
age methodology counting growth layers demography grinding teeth mortality toothed whale |
description |
Age determination of marine mammals is important for understanding the impact of anthropogenic disturbances as well as for population management. Toothed whales are usually age-determined by counting annually formed layers in their teeth. This includes a time-consuming sequence of preparations, usually involving chemical treatment. This study tested a quicker and simpler method for age determination of harbour porpoises (Phocoena phocoena), originally developed for age determination of foxes and other terrestrial carnivores. The tooth was ground with fine-grained sandpaper, and the age lines were directly read using a binocular microscope. To evaluate the usability of the grinding method for harbour porpoises, three tests were used: (1) the number of growth layer groups (GLGs) in teeth from 66 harbour porpoises by the grinding method were compared by two readers; (2) GLGs in teeth from six harbour porpoises prepared by the grinding method and by the decalcification method were compared in a blinded set-up with two readers; and (3) the GLGs in teeth from two individuals with known ages prepared by both the grinding method and the decalcification method, respectively, were compared. A Bland–Altman plot showed high agreement between the determined age of individuals by the two different methods. The average age difference was -0.56 years, and the 95% confidence interval for the average difference was [-4.3, 3.2] years. The grinding method is therefore considered to be a valid alternative and quicker method for age determination of harbour porpoises. |
format |
Article in Journal/Newspaper |
author |
Henriksen, Louise B. Thøstesen, Charlotte Bie Alstrup, Aage Kristian Olsen Larsen, Hanne Lyngholm Wahlberg, Magnus Siebert, Ursula Pagh, Sussie |
author_facet |
Henriksen, Louise B. Thøstesen, Charlotte Bie Alstrup, Aage Kristian Olsen Larsen, Hanne Lyngholm Wahlberg, Magnus Siebert, Ursula Pagh, Sussie |
author_sort |
Henriksen, Louise B. |
title |
A New Simple Method for Age Determination of Harbour Porpoises (Phocoena phocoena) |
title_short |
A New Simple Method for Age Determination of Harbour Porpoises (Phocoena phocoena) |
title_full |
A New Simple Method for Age Determination of Harbour Porpoises (Phocoena phocoena) |
title_fullStr |
A New Simple Method for Age Determination of Harbour Porpoises (Phocoena phocoena) |
title_full_unstemmed |
A New Simple Method for Age Determination of Harbour Porpoises (Phocoena phocoena) |
title_sort |
new simple method for age determination of harbour porpoises (phocoena phocoena) |
publishDate |
2024 |
url |
https://portal.findresearcher.sdu.dk/da/publications/d265ff8a-f827-4a69-aea4-b7ec044cb08e https://doi.org/10.1578/AM.50.1.2024.30 |
genre |
Phocoena phocoena toothed whale toothed whales |
genre_facet |
Phocoena phocoena toothed whale toothed whales |
op_source |
Henriksen , L B , Thøstesen , C B , Alstrup , A K O , Larsen , H L , Wahlberg , M , Siebert , U & Pagh , S 2024 , ' A New Simple Method for Age Determination of Harbour Porpoises (Phocoena phocoena) ' , Aquatic Mammals , vol. 50 , no. 1 , pp. 30-38 . https://doi.org/10.1578/AM.50.1.2024.30 |
op_relation |
https://portal.findresearcher.sdu.dk/da/publications/d265ff8a-f827-4a69-aea4-b7ec044cb08e |
op_rights |
info:eu-repo/semantics/closedAccess |
op_doi |
https://doi.org/10.1578/AM.50.1.2024.30 |
container_title |
Aquatic Mammals |
container_volume |
50 |
container_issue |
1 |
container_start_page |
30 |
op_container_end_page |
38 |
_version_ |
1799487768861081600 |