Rescaling of aerial survey data with information from small numbers of telemetry tags to estimate the size of a declining harbour seal population
ABSTRACT Estimates of both absolute abundance and trends in abundance are among the most basic pieces of information required for planning the conservation and management of wildlife populations. They are important for understanding both the current situation of species and potential risks to them....
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crwiley:10.1002/aqc.2277 2024-06-02T08:07:48+00:00 Rescaling of aerial survey data with information from small numbers of telemetry tags to estimate the size of a declining harbour seal population Lonergan, Mike Duck, Callan Moss, Simon Morris, Chris Thompson, Dave 2012 http://dx.doi.org/10.1002/aqc.2277 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Faqc.2277 https://onlinelibrary.wiley.com/doi/pdf/10.1002/aqc.2277 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Aquatic Conservation: Marine and Freshwater Ecosystems volume 23, issue 1, page 135-144 ISSN 1052-7613 1099-0755 journal-article 2012 crwiley https://doi.org/10.1002/aqc.2277 2024-05-03T11:47:43Z ABSTRACT Estimates of both absolute abundance and trends in abundance are among the most basic pieces of information required for planning the conservation and management of wildlife populations. They are important for understanding both the current situation of species and potential risks to them. This study presents estimates of the size of the harbour seal ( Phoca vitulina ) population associated with the Orkney Islands, a part of northern Scotland that used to contain one of the largest concentrations of this species in Europe. The numbers of animals counted during aerial surveys of this area have decreased substantially over the period 2001–2010. ARGOS transmitters attached to flipper tags were used to rescale the counts into estimates of abundance and to confirm the rate of decline of this population. Females hauled out for more of the survey window (0.84; bootstrap 95% CI: 0.63–0.99) than males (0.61; bootstrap 95% CI: 0.34–0.86). The animals hauled out less during weekends (0.57; bootstrap 95% CI: 0.40–0.74) than during the week (0.76; bootstrap 95% CI: 0.58–0.91). The sex‐ratios of this population is unknown. Assuming it was close to 1:1, then there were around 3586 (bootstrap 95% CI: 2970–4542) harbour seals in Orkney in 2010. A female‐skewed sex‐ratio would reduce the population estimate, and a changing sex‐ratio might mean the counts understate the real decline. The mean annual rate of decline in the Orkney population of harbour seals, over the period 2001–2010, is estimated at 13% (95% CI: 10.8–14.8). Similar data for Arisaig, on the west coast of Scotland, shows an increase of around 2% (95% CI: 1.5–2.4) and, assuming an equal sex‐ratio, 923 animals (95% CI: 765–1169) in 2007. Copyright © 2012 John Wiley & Sons, Ltd. Article in Journal/Newspaper harbour seal Phoca vitulina Wiley Online Library Aquatic Conservation: Marine and Freshwater Ecosystems 23 1 135 144 |
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Open Polar |
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Wiley Online Library |
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crwiley |
language |
English |
description |
ABSTRACT Estimates of both absolute abundance and trends in abundance are among the most basic pieces of information required for planning the conservation and management of wildlife populations. They are important for understanding both the current situation of species and potential risks to them. This study presents estimates of the size of the harbour seal ( Phoca vitulina ) population associated with the Orkney Islands, a part of northern Scotland that used to contain one of the largest concentrations of this species in Europe. The numbers of animals counted during aerial surveys of this area have decreased substantially over the period 2001–2010. ARGOS transmitters attached to flipper tags were used to rescale the counts into estimates of abundance and to confirm the rate of decline of this population. Females hauled out for more of the survey window (0.84; bootstrap 95% CI: 0.63–0.99) than males (0.61; bootstrap 95% CI: 0.34–0.86). The animals hauled out less during weekends (0.57; bootstrap 95% CI: 0.40–0.74) than during the week (0.76; bootstrap 95% CI: 0.58–0.91). The sex‐ratios of this population is unknown. Assuming it was close to 1:1, then there were around 3586 (bootstrap 95% CI: 2970–4542) harbour seals in Orkney in 2010. A female‐skewed sex‐ratio would reduce the population estimate, and a changing sex‐ratio might mean the counts understate the real decline. The mean annual rate of decline in the Orkney population of harbour seals, over the period 2001–2010, is estimated at 13% (95% CI: 10.8–14.8). Similar data for Arisaig, on the west coast of Scotland, shows an increase of around 2% (95% CI: 1.5–2.4) and, assuming an equal sex‐ratio, 923 animals (95% CI: 765–1169) in 2007. Copyright © 2012 John Wiley & Sons, Ltd. |
format |
Article in Journal/Newspaper |
author |
Lonergan, Mike Duck, Callan Moss, Simon Morris, Chris Thompson, Dave |
spellingShingle |
Lonergan, Mike Duck, Callan Moss, Simon Morris, Chris Thompson, Dave Rescaling of aerial survey data with information from small numbers of telemetry tags to estimate the size of a declining harbour seal population |
author_facet |
Lonergan, Mike Duck, Callan Moss, Simon Morris, Chris Thompson, Dave |
author_sort |
Lonergan, Mike |
title |
Rescaling of aerial survey data with information from small numbers of telemetry tags to estimate the size of a declining harbour seal population |
title_short |
Rescaling of aerial survey data with information from small numbers of telemetry tags to estimate the size of a declining harbour seal population |
title_full |
Rescaling of aerial survey data with information from small numbers of telemetry tags to estimate the size of a declining harbour seal population |
title_fullStr |
Rescaling of aerial survey data with information from small numbers of telemetry tags to estimate the size of a declining harbour seal population |
title_full_unstemmed |
Rescaling of aerial survey data with information from small numbers of telemetry tags to estimate the size of a declining harbour seal population |
title_sort |
rescaling of aerial survey data with information from small numbers of telemetry tags to estimate the size of a declining harbour seal population |
publisher |
Wiley |
publishDate |
2012 |
url |
http://dx.doi.org/10.1002/aqc.2277 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Faqc.2277 https://onlinelibrary.wiley.com/doi/pdf/10.1002/aqc.2277 |
genre |
harbour seal Phoca vitulina |
genre_facet |
harbour seal Phoca vitulina |
op_source |
Aquatic Conservation: Marine and Freshwater Ecosystems volume 23, issue 1, page 135-144 ISSN 1052-7613 1099-0755 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1002/aqc.2277 |
container_title |
Aquatic Conservation: Marine and Freshwater Ecosystems |
container_volume |
23 |
container_issue |
1 |
container_start_page |
135 |
op_container_end_page |
144 |
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1800752923912699904 |