Abundance of the Eastern Chukchi Sea Stock of Beluga Whales, 2012 – 17
Aerial line transect surveys were conducted during 19 July – 20 August in each of the years 2012 – 17, with onshore – offshore transects covering a study area of approximately 110 000 km2, from 140˚ W to 157˚ W longitude and from shore to 72˚ N latitude. These data were used to estimate abundance of...
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crarcticinstna:10.14430/arctic71592 2024-06-09T07:42:14+00:00 Abundance of the Eastern Chukchi Sea Stock of Beluga Whales, 2012 – 17 Givens, Geof H. Ferguson, Megan C. Clarke, Janet T. Willoughby, Amy Brower, Amelia Suydam, Robert 2020 http://dx.doi.org/10.14430/arctic71592 https://journalhosting.ucalgary.ca/index.php/arctic/article/download/71592/54593 unknown The Arctic Institute of North America http://creativecommons.org/licenses/by/4.0/ ARCTIC volume 73, issue 4, page 485-498 ISSN 1923-1245 0004-0843 journal-article 2020 crarcticinstna https://doi.org/10.14430/arctic71592 2024-05-14T12:53:43Z Aerial line transect surveys were conducted during 19 July – 20 August in each of the years 2012 – 17, with onshore – offshore transects covering a study area of approximately 110 000 km2, from 140˚ W to 157˚ W longitude and from shore to 72˚ N latitude. These data were used to estimate abundance of the eastern Chukchi Sea (ECS) stock of beluga whales. The data were stratified based on bathymetry to reflect strong large-scale gradients in beluga density. A half-normal key function was used to model detection from a dataset of 999 sightings of 2465 belugas. The detection function was found to depend significantly on sky condition and ice coverage. For the years 2012 through 2017, respectively, the estimated numbers of ECS belugas in the study area during the study period were 7355 (CV = 0.17), 6813 (CV = 0.18), 16 598 (CV = 0.21), 6456 (CV = 0.21), 6965 (CV = 0.23) and 13 305 (CV = 0.27). There is no statistically significant trend. These estimates do not correct for belugas outside the study region. Indeed, diverse data indicate that belugas venture far outside the study region and their distribution varies interannually due to prey availability and other factors. Recently reviewed tagging data suggest that correcting for whales outside the study area would approximately double our abundance estimates. These results provide no indication that the stock has substantially declined during these six years due to the impact of subsistence hunting, industrial activity or climate change, although interannual variation and estimated CVs are both large, thereby potentially masking small-scale impacts. Article in Journal/Newspaper Arctic Beluga Beluga* Chukchi Chukchi Sea Arctic Institute of North America Chukchi Sea ARCTIC 73 4 485 498 |
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Open Polar |
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Arctic Institute of North America |
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crarcticinstna |
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unknown |
description |
Aerial line transect surveys were conducted during 19 July – 20 August in each of the years 2012 – 17, with onshore – offshore transects covering a study area of approximately 110 000 km2, from 140˚ W to 157˚ W longitude and from shore to 72˚ N latitude. These data were used to estimate abundance of the eastern Chukchi Sea (ECS) stock of beluga whales. The data were stratified based on bathymetry to reflect strong large-scale gradients in beluga density. A half-normal key function was used to model detection from a dataset of 999 sightings of 2465 belugas. The detection function was found to depend significantly on sky condition and ice coverage. For the years 2012 through 2017, respectively, the estimated numbers of ECS belugas in the study area during the study period were 7355 (CV = 0.17), 6813 (CV = 0.18), 16 598 (CV = 0.21), 6456 (CV = 0.21), 6965 (CV = 0.23) and 13 305 (CV = 0.27). There is no statistically significant trend. These estimates do not correct for belugas outside the study region. Indeed, diverse data indicate that belugas venture far outside the study region and their distribution varies interannually due to prey availability and other factors. Recently reviewed tagging data suggest that correcting for whales outside the study area would approximately double our abundance estimates. These results provide no indication that the stock has substantially declined during these six years due to the impact of subsistence hunting, industrial activity or climate change, although interannual variation and estimated CVs are both large, thereby potentially masking small-scale impacts. |
format |
Article in Journal/Newspaper |
author |
Givens, Geof H. Ferguson, Megan C. Clarke, Janet T. Willoughby, Amy Brower, Amelia Suydam, Robert |
spellingShingle |
Givens, Geof H. Ferguson, Megan C. Clarke, Janet T. Willoughby, Amy Brower, Amelia Suydam, Robert Abundance of the Eastern Chukchi Sea Stock of Beluga Whales, 2012 – 17 |
author_facet |
Givens, Geof H. Ferguson, Megan C. Clarke, Janet T. Willoughby, Amy Brower, Amelia Suydam, Robert |
author_sort |
Givens, Geof H. |
title |
Abundance of the Eastern Chukchi Sea Stock of Beluga Whales, 2012 – 17 |
title_short |
Abundance of the Eastern Chukchi Sea Stock of Beluga Whales, 2012 – 17 |
title_full |
Abundance of the Eastern Chukchi Sea Stock of Beluga Whales, 2012 – 17 |
title_fullStr |
Abundance of the Eastern Chukchi Sea Stock of Beluga Whales, 2012 – 17 |
title_full_unstemmed |
Abundance of the Eastern Chukchi Sea Stock of Beluga Whales, 2012 – 17 |
title_sort |
abundance of the eastern chukchi sea stock of beluga whales, 2012 – 17 |
publisher |
The Arctic Institute of North America |
publishDate |
2020 |
url |
http://dx.doi.org/10.14430/arctic71592 https://journalhosting.ucalgary.ca/index.php/arctic/article/download/71592/54593 |
geographic |
Chukchi Sea |
geographic_facet |
Chukchi Sea |
genre |
Arctic Beluga Beluga* Chukchi Chukchi Sea |
genre_facet |
Arctic Beluga Beluga* Chukchi Chukchi Sea |
op_source |
ARCTIC volume 73, issue 4, page 485-498 ISSN 1923-1245 0004-0843 |
op_rights |
http://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.14430/arctic71592 |
container_title |
ARCTIC |
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73 |
container_issue |
4 |
container_start_page |
485 |
op_container_end_page |
498 |
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1801371123652231168 |