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...
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Septentrio Academic Publishing
2019
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Online Access: | https://doi.org/10.7557/3.4643 https://doaj.org/article/cc6c8d5c016b46ad9989b7b6c0f9fe8b |
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ftdoajarticles:oai:doaj.org/article:cc6c8d5c016b46ad9989b7b6c0f9fe8b 2023-05-15T17:30:09+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 Daniel G. Pike Thorvaldur Gunnlaugsson Geneviève Desportes Bjarni Mikkelsen Gísli A. Vikingsson Dorete Bloch 2019-02-01T00:00:00Z https://doi.org/10.7557/3.4643 https://doaj.org/article/cc6c8d5c016b46ad9989b7b6c0f9fe8b EN eng Septentrio Academic Publishing https://septentrio.uit.no/index.php/NAMMCOSP/article/view/4643 https://doaj.org/toc/1560-2206 https://doaj.org/toc/2309-2491 doi:10.7557/3.4643 1560-2206 2309-2491 https://doaj.org/article/cc6c8d5c016b46ad9989b7b6c0f9fe8b NAMMCO Scientific Publications, Vol 11 (2019) Long-finned pilot whale Globicephala melas North Atlantic surveys abundance trends Ecology QH540-549.5 article 2019 ftdoajarticles https://doi.org/10.7557/3.4643 2022-12-30T23:57:27Z 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 Directory of Open Access Journals: DOAJ Articles NAMMCO Scientific Publications 11 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Long-finned pilot whale Globicephala melas North Atlantic surveys abundance trends Ecology QH540-549.5 |
spellingShingle |
Long-finned pilot whale Globicephala melas North Atlantic surveys abundance trends Ecology QH540-549.5 Daniel G. Pike Thorvaldur Gunnlaugsson Geneviève Desportes Bjarni Mikkelsen Gísli A. Vikingsson Dorete Bloch 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 Ecology QH540-549.5 |
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 |
Daniel G. Pike Thorvaldur Gunnlaugsson Geneviève Desportes Bjarni Mikkelsen Gísli A. Vikingsson Dorete Bloch |
author_facet |
Daniel G. Pike Thorvaldur Gunnlaugsson Geneviève Desportes Bjarni Mikkelsen Gísli A. Vikingsson Dorete Bloch |
author_sort |
Daniel G. Pike |
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://doi.org/10.7557/3.4643 https://doaj.org/article/cc6c8d5c016b46ad9989b7b6c0f9fe8b |
genre |
North Atlantic Northeast Atlantic |
genre_facet |
North Atlantic Northeast Atlantic |
op_source |
NAMMCO Scientific Publications, Vol 11 (2019) |
op_relation |
https://septentrio.uit.no/index.php/NAMMCOSP/article/view/4643 https://doaj.org/toc/1560-2206 https://doaj.org/toc/2309-2491 doi:10.7557/3.4643 1560-2206 2309-2491 https://doaj.org/article/cc6c8d5c016b46ad9989b7b6c0f9fe8b |
op_doi |
https://doi.org/10.7557/3.4643 |
container_title |
NAMMCO Scientific Publications |
container_volume |
11 |
_version_ |
1766125971539230720 |