Estimates of the Relative Abundance of Long-finned Pilot Whales (Globicephala melas) in the Northeast Atlantic from 1987 to 2015 indicate no long-term trends
North Atlantic Sightings Surveys (NASS) and associated surveys, covering a large but variable portion of the North Atlantic, were conducted in 1987, 1989, 1995, 2001, 2007 and 2015. Previous estimates of long-finned pilot whale (Globicephala melas) abundance, derived using conventional distance samp...
Published in: | NAMMCO Scientific Publications |
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Main Authors: | , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Septentrio Academic Publishing
2019
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Subjects: | |
Online Access: | https://septentrio.uit.no/index.php/NAMMCOSP/article/view/4643 https://doi.org/10.7557/3.4643 |
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ftunitroemsoe:oai:ojs.henry.ub.uit.no:article/4643 |
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record_format |
openpolar |
institution |
Open Polar |
collection |
University of Tromsø: Septentrio Academic Publishing |
op_collection_id |
ftunitroemsoe |
language |
English |
topic |
Long-finned pilot whale Globicephala melas North Atlantic surveys abundance trends |
spellingShingle |
Long-finned pilot whale Globicephala melas North Atlantic surveys abundance trends Pike, Daniel G. Gunnlaugsson, Thorvaldur Desportes, Geneviève Mikkelsen, Bjarni Víkingsson, Gísli Bloch, Dorete Estimates of the Relative Abundance of Long-finned Pilot Whales (Globicephala melas) in the Northeast Atlantic from 1987 to 2015 indicate no long-term trends |
topic_facet |
Long-finned pilot whale Globicephala melas North Atlantic surveys abundance trends |
description |
North Atlantic Sightings Surveys (NASS) and associated surveys, covering a large but variable portion of the North Atlantic, were conducted in 1987, 1989, 1995, 2001, 2007 and 2015. Previous estimates of long-finned pilot whale (Globicephala melas) abundance, derived using conventional distance sampling (CDS), are not directly comparable to one another because of differing survey coverage, field methods and, in the case of the 1989 NASS, different survey timing. CDS was used to develop indices of relative abundance to determine if pilot whale abundance has changed over the 28-year period from 1987 to 2015. The varying spatial coverage of the surveys is accommodated by delineating common regions that were covered by: i) all 6 surveys, and ii) the 3 largest surveys (1989, 1995, and 2007). These “Index Regions” were divided into East and West subregions, and post-stratification was used to obtain abundance estimates for these index areas only. Estimates are provided using the sightings from the combined platforms for surveys that used double platforms or the primary platform only. Total abundance in the Index Regions, uncorrected for perception or availability biases, ranged from 54,264 (CV=0.48) in 2001 to 253,109 (CV=0.43) in 2015. There was no significant trend in the numbers of individuals or groups in either the 6 or 3 Survey Index Regions, and no consistent trend over the period. Power analyses indicate that negative annual growth rates of -3% to -5% would have been detectible over the entire period. The Index Regions comprise only a portion of the summer range of the species and changes in annual distribution clearly affect the results. Operational changes to the surveys, particularly in defining pilot whale groups, may also have introduced biases. Recommendations for future monitoring of the long-finned pilot whale population are provided. |
format |
Article in Journal/Newspaper |
author |
Pike, Daniel G. Gunnlaugsson, Thorvaldur Desportes, Geneviève Mikkelsen, Bjarni Víkingsson, Gísli Bloch, Dorete |
author_facet |
Pike, Daniel G. Gunnlaugsson, Thorvaldur Desportes, Geneviève Mikkelsen, Bjarni Víkingsson, Gísli Bloch, Dorete |
author_sort |
Pike, Daniel G. |
title |
Estimates of the Relative Abundance of Long-finned Pilot Whales (Globicephala melas) in the Northeast Atlantic from 1987 to 2015 indicate no long-term trends |
title_short |
Estimates of the Relative Abundance of Long-finned Pilot Whales (Globicephala melas) in the Northeast Atlantic from 1987 to 2015 indicate no long-term trends |
title_full |
Estimates of the Relative Abundance of Long-finned Pilot Whales (Globicephala melas) in the Northeast Atlantic from 1987 to 2015 indicate no long-term trends |
title_fullStr |
Estimates of the Relative Abundance of Long-finned Pilot Whales (Globicephala melas) in the Northeast Atlantic from 1987 to 2015 indicate no long-term trends |
title_full_unstemmed |
Estimates of the Relative Abundance of Long-finned Pilot Whales (Globicephala melas) in the Northeast Atlantic from 1987 to 2015 indicate no long-term trends |
title_sort |
estimates of the relative abundance of long-finned pilot whales (globicephala melas) in the northeast atlantic from 1987 to 2015 indicate no long-term trends |
publisher |
Septentrio Academic Publishing |
publishDate |
2019 |
url |
https://septentrio.uit.no/index.php/NAMMCOSP/article/view/4643 https://doi.org/10.7557/3.4643 |
genre |
North Atlantic Northeast Atlantic |
genre_facet |
North Atlantic Northeast Atlantic |
op_source |
NAMMCO Scientific Publications; Vol. 11 (2019): Sightings Surveys in the North Atlantic: 30 years of counting whales 2309-2491 1560-2206 10.7557/3.11 |
op_relation |
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op_rights |
Copyright (c) 2019 Daniel G. Pike, Thorvaldur Gunnlaugsson, Geneviève Desportes, Bjarni Mikkelsen, Gísli A. Vikingsson, Dorete Bloch https://creativecommons.org/licenses/by/4.0 |
op_doi |
https://doi.org/10.7557/3.464310.7557/3.11 |
container_title |
NAMMCO Scientific Publications |
container_volume |
11 |
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spelling |
ftunitroemsoe:oai:ojs.henry.ub.uit.no:article/4643 2023-10-09T21:53:55+02:00 Estimates of the Relative Abundance of Long-finned Pilot Whales (Globicephala melas) in the Northeast Atlantic from 1987 to 2015 indicate no long-term trends Pike, Daniel G. Gunnlaugsson, Thorvaldur Desportes, Geneviève Mikkelsen, Bjarni Víkingsson, Gísli Bloch, Dorete 2019-02-12 application/pdf image/tiff image/jpeg https://septentrio.uit.no/index.php/NAMMCOSP/article/view/4643 https://doi.org/10.7557/3.4643 eng eng Septentrio Academic Publishing https://septentrio.uit.no/index.php/NAMMCOSP/article/view/4643/4677 https://septentrio.uit.no/index.php/NAMMCOSP/article/view/4643/5626 https://septentrio.uit.no/index.php/NAMMCOSP/article/view/4643/5627 https://septentrio.uit.no/index.php/NAMMCOSP/article/view/4643/5628 https://septentrio.uit.no/index.php/NAMMCOSP/article/view/4643/5629 https://septentrio.uit.no/index.php/NAMMCOSP/article/view/4643/5630 https://septentrio.uit.no/index.php/NAMMCOSP/article/view/4643/5631 https://septentrio.uit.no/index.php/NAMMCOSP/article/view/4643/5632 https://septentrio.uit.no/index.php/NAMMCOSP/article/view/4643/5633 https://septentrio.uit.no/index.php/NAMMCOSP/article/view/4643/5634 https://septentrio.uit.no/index.php/NAMMCOSP/article/view/4643/5635 https://septentrio.uit.no/index.php/NAMMCOSP/article/view/4643/5636 https://septentrio.uit.no/index.php/NAMMCOSP/article/view/4643/5637 https://septentrio.uit.no/index.php/NAMMCOSP/article/view/4643/5638 https://septentrio.uit.no/index.php/NAMMCOSP/article/view/4643/5639 https://septentrio.uit.no/index.php/NAMMCOSP/article/view/4643/5640 https://septentrio.uit.no/index.php/NAMMCOSP/article/view/4643 doi:10.7557/3.4643 Copyright (c) 2019 Daniel G. Pike, Thorvaldur Gunnlaugsson, Geneviève Desportes, Bjarni Mikkelsen, Gísli A. Vikingsson, Dorete Bloch https://creativecommons.org/licenses/by/4.0 NAMMCO Scientific Publications; Vol. 11 (2019): Sightings Surveys in the North Atlantic: 30 years of counting whales 2309-2491 1560-2206 10.7557/3.11 Long-finned pilot whale Globicephala melas North Atlantic surveys abundance trends info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 2019 ftunitroemsoe https://doi.org/10.7557/3.464310.7557/3.11 2023-09-20T23:07:55Z North Atlantic Sightings Surveys (NASS) and associated surveys, covering a large but variable portion of the North Atlantic, were conducted in 1987, 1989, 1995, 2001, 2007 and 2015. Previous estimates of long-finned pilot whale (Globicephala melas) abundance, derived using conventional distance sampling (CDS), are not directly comparable to one another because of differing survey coverage, field methods and, in the case of the 1989 NASS, different survey timing. CDS was used to develop indices of relative abundance to determine if pilot whale abundance has changed over the 28-year period from 1987 to 2015. The varying spatial coverage of the surveys is accommodated by delineating common regions that were covered by: i) all 6 surveys, and ii) the 3 largest surveys (1989, 1995, and 2007). These “Index Regions” were divided into East and West subregions, and post-stratification was used to obtain abundance estimates for these index areas only. Estimates are provided using the sightings from the combined platforms for surveys that used double platforms or the primary platform only. Total abundance in the Index Regions, uncorrected for perception or availability biases, ranged from 54,264 (CV=0.48) in 2001 to 253,109 (CV=0.43) in 2015. There was no significant trend in the numbers of individuals or groups in either the 6 or 3 Survey Index Regions, and no consistent trend over the period. Power analyses indicate that negative annual growth rates of -3% to -5% would have been detectible over the entire period. The Index Regions comprise only a portion of the summer range of the species and changes in annual distribution clearly affect the results. Operational changes to the surveys, particularly in defining pilot whale groups, may also have introduced biases. Recommendations for future monitoring of the long-finned pilot whale population are provided. Article in Journal/Newspaper North Atlantic Northeast Atlantic University of Tromsø: Septentrio Academic Publishing NAMMCO Scientific Publications 11 |