Abundance decline in the narrow‐ridged finless porpoise population off the Pacific coast of eastern Japan
Abstract The narrow‐ridged finless porpoise Neophocaena asiaeorientalis is a small‐toothed whale with a coastal habitat and is sensitive to human activity. Aerial sighting surveys were conducted in 2012 to evaluate the abundance and distribution of the Sendai Bay‐Tokyo Bay population off the Pacific...
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crwiley:10.1002/1438-390x.12003 2024-09-15T18:39:11+00:00 Abundance decline in the narrow‐ridged finless porpoise population off the Pacific coast of eastern Japan Shirakihara, Kunio Nakahara, Fumio Shinohara, Masanori Shirakihara, Miki Hiramatsu, Kazuhiko Irie, Takahiro Tohoku Ecosystem-Associated Marine Sciences from the Ministry of Education, Culture, Sports, Science and Technology 2019 http://dx.doi.org/10.1002/1438-390x.12003 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F1438-390X.12003 https://onlinelibrary.wiley.com/doi/pdf/10.1002/1438-390X.12003 https://onlinelibrary.wiley.com/doi/full-xml/10.1002/1438-390X.12003 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Population Ecology volume 61, issue 3, page 325-332 ISSN 1438-3896 1438-390X journal-article 2019 crwiley https://doi.org/10.1002/1438-390x.12003 2024-07-30T04:19:57Z Abstract The narrow‐ridged finless porpoise Neophocaena asiaeorientalis is a small‐toothed whale with a coastal habitat and is sensitive to human activity. Aerial sighting surveys were conducted in 2012 to evaluate the abundance and distribution of the Sendai Bay‐Tokyo Bay population off the Pacific coast of eastern Japan. We flew along 35 east–west transects at intervals of 11.6 km over the study area between 34°57′ and 38°21’ N. In total, 25 groups were detected by two observers. The mean group size was 1.44 individuals. Porpoise abundance was estimated to be 1,491 individuals (coefficient of variation = 32.4%), which was lower than the abundance estimated in 2000 ( z test, p < 0.05). A population decline trend during 2000–2012 was also detected using four available abundance estimates (Bootstrapping linear regression, p = 0.040). A possible cause of this decline was coastal habitat disturbance and deaths by tsunami waves caused by the 2011 Great East Japan Earthquake. Density was as low as 0.221 individuals/km 2 , which is among the lowest levels in Japanese waters. Furthermore, distributional gaps reconfirmed by the present study and past genetic studies show that the population should be divided into at least two populations: northern (“Sendai Bay‐Fukushima”) and southern. Density decline was detected in the northern population between 2000 and 2012. Unlike the earthquake, human activities may continue to affect the porpoises. Viability analyses of these small populations should be conducted in the future. Article in Journal/Newspaper toothed whale Wiley Online Library Population Ecology 61 3 325 332 |
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Wiley Online Library |
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crwiley |
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English |
description |
Abstract The narrow‐ridged finless porpoise Neophocaena asiaeorientalis is a small‐toothed whale with a coastal habitat and is sensitive to human activity. Aerial sighting surveys were conducted in 2012 to evaluate the abundance and distribution of the Sendai Bay‐Tokyo Bay population off the Pacific coast of eastern Japan. We flew along 35 east–west transects at intervals of 11.6 km over the study area between 34°57′ and 38°21’ N. In total, 25 groups were detected by two observers. The mean group size was 1.44 individuals. Porpoise abundance was estimated to be 1,491 individuals (coefficient of variation = 32.4%), which was lower than the abundance estimated in 2000 ( z test, p < 0.05). A population decline trend during 2000–2012 was also detected using four available abundance estimates (Bootstrapping linear regression, p = 0.040). A possible cause of this decline was coastal habitat disturbance and deaths by tsunami waves caused by the 2011 Great East Japan Earthquake. Density was as low as 0.221 individuals/km 2 , which is among the lowest levels in Japanese waters. Furthermore, distributional gaps reconfirmed by the present study and past genetic studies show that the population should be divided into at least two populations: northern (“Sendai Bay‐Fukushima”) and southern. Density decline was detected in the northern population between 2000 and 2012. Unlike the earthquake, human activities may continue to affect the porpoises. Viability analyses of these small populations should be conducted in the future. |
author2 |
Tohoku Ecosystem-Associated Marine Sciences from the Ministry of Education, Culture, Sports, Science and Technology |
format |
Article in Journal/Newspaper |
author |
Shirakihara, Kunio Nakahara, Fumio Shinohara, Masanori Shirakihara, Miki Hiramatsu, Kazuhiko Irie, Takahiro |
spellingShingle |
Shirakihara, Kunio Nakahara, Fumio Shinohara, Masanori Shirakihara, Miki Hiramatsu, Kazuhiko Irie, Takahiro Abundance decline in the narrow‐ridged finless porpoise population off the Pacific coast of eastern Japan |
author_facet |
Shirakihara, Kunio Nakahara, Fumio Shinohara, Masanori Shirakihara, Miki Hiramatsu, Kazuhiko Irie, Takahiro |
author_sort |
Shirakihara, Kunio |
title |
Abundance decline in the narrow‐ridged finless porpoise population off the Pacific coast of eastern Japan |
title_short |
Abundance decline in the narrow‐ridged finless porpoise population off the Pacific coast of eastern Japan |
title_full |
Abundance decline in the narrow‐ridged finless porpoise population off the Pacific coast of eastern Japan |
title_fullStr |
Abundance decline in the narrow‐ridged finless porpoise population off the Pacific coast of eastern Japan |
title_full_unstemmed |
Abundance decline in the narrow‐ridged finless porpoise population off the Pacific coast of eastern Japan |
title_sort |
abundance decline in the narrow‐ridged finless porpoise population off the pacific coast of eastern japan |
publisher |
Wiley |
publishDate |
2019 |
url |
http://dx.doi.org/10.1002/1438-390x.12003 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F1438-390X.12003 https://onlinelibrary.wiley.com/doi/pdf/10.1002/1438-390X.12003 https://onlinelibrary.wiley.com/doi/full-xml/10.1002/1438-390X.12003 |
genre |
toothed whale |
genre_facet |
toothed whale |
op_source |
Population Ecology volume 61, issue 3, page 325-332 ISSN 1438-3896 1438-390X |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1002/1438-390x.12003 |
container_title |
Population Ecology |
container_volume |
61 |
container_issue |
3 |
container_start_page |
325 |
op_container_end_page |
332 |
_version_ |
1810483578679590912 |