To see or not to see: investigating detectability of Ganges River dolphins using a combined visual-acoustic survey.

Detection of animals during visual surveys is rarely perfect or constant, and failure to account for imperfect detectability affects the accuracy of abundance estimates. Freshwater cetaceans are among the most threatened group of mammals, and visual surveys are a commonly employed method for estimat...

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Autores principales:	Nadia I Richman, James M Gibbons, Samuel T Turvey, Tomonari Akamatsu, Benazir Ahmed, Emile Mahabub, Brian D Smith, Julia P G Jones
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2014
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/c10507e8b5944abeb1d83d31e83174a4
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id	oai:doaj.org-article:c10507e8b5944abeb1d83d31e83174a4
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spelling	oai:doaj.org-article:c10507e8b5944abeb1d83d31e83174a42021-11-18T08:20:22ZTo see or not to see: investigating detectability of Ganges River dolphins using a combined visual-acoustic survey.1932-620310.1371/journal.pone.0096811https://doaj.org/article/c10507e8b5944abeb1d83d31e83174a42014-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/24805782/?tool=EBIhttps://doaj.org/toc/1932-6203Detection of animals during visual surveys is rarely perfect or constant, and failure to account for imperfect detectability affects the accuracy of abundance estimates. Freshwater cetaceans are among the most threatened group of mammals, and visual surveys are a commonly employed method for estimating population size despite concerns over imperfect and unquantified detectability. We used a combined visual-acoustic survey to estimate detectability of Ganges River dolphins (Platanista gangetica gangetica) in four waterways of southern Bangladesh. The combined visual-acoustic survey resulted in consistently higher detectability than a single observer-team visual survey, thereby improving power to detect trends. Visual detectability was particularly low for dolphins close to meanders where these habitat features temporarily block the view of the preceding river surface. This systematic bias in detectability during visual-only surveys may lead researchers to underestimate the importance of heavily meandering river reaches. Although the benefits of acoustic surveys are increasingly recognised for marine cetaceans, they have not been widely used for monitoring abundance of freshwater cetaceans due to perceived costs and technical skill requirements. We show that acoustic surveys are in fact a relatively cost-effective approach for surveying freshwater cetaceans, once it is acknowledged that methods that do not account for imperfect detectability are of limited value for monitoring.Nadia I RichmanJames M GibbonsSamuel T TurveyTomonari AkamatsuBenazir AhmedEmile MahabubBrian D SmithJulia P G JonesPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 9, Iss 5, p e96811 (2014)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Nadia I Richman James M Gibbons Samuel T Turvey Tomonari Akamatsu Benazir Ahmed Emile Mahabub Brian D Smith Julia P G Jones To see or not to see: investigating detectability of Ganges River dolphins using a combined visual-acoustic survey.
description	Detection of animals during visual surveys is rarely perfect or constant, and failure to account for imperfect detectability affects the accuracy of abundance estimates. Freshwater cetaceans are among the most threatened group of mammals, and visual surveys are a commonly employed method for estimating population size despite concerns over imperfect and unquantified detectability. We used a combined visual-acoustic survey to estimate detectability of Ganges River dolphins (Platanista gangetica gangetica) in four waterways of southern Bangladesh. The combined visual-acoustic survey resulted in consistently higher detectability than a single observer-team visual survey, thereby improving power to detect trends. Visual detectability was particularly low for dolphins close to meanders where these habitat features temporarily block the view of the preceding river surface. This systematic bias in detectability during visual-only surveys may lead researchers to underestimate the importance of heavily meandering river reaches. Although the benefits of acoustic surveys are increasingly recognised for marine cetaceans, they have not been widely used for monitoring abundance of freshwater cetaceans due to perceived costs and technical skill requirements. We show that acoustic surveys are in fact a relatively cost-effective approach for surveying freshwater cetaceans, once it is acknowledged that methods that do not account for imperfect detectability are of limited value for monitoring.
format	article
author	Nadia I Richman James M Gibbons Samuel T Turvey Tomonari Akamatsu Benazir Ahmed Emile Mahabub Brian D Smith Julia P G Jones
author_facet	Nadia I Richman James M Gibbons Samuel T Turvey Tomonari Akamatsu Benazir Ahmed Emile Mahabub Brian D Smith Julia P G Jones
author_sort	Nadia I Richman
title	To see or not to see: investigating detectability of Ganges River dolphins using a combined visual-acoustic survey.
title_short	To see or not to see: investigating detectability of Ganges River dolphins using a combined visual-acoustic survey.
title_full	To see or not to see: investigating detectability of Ganges River dolphins using a combined visual-acoustic survey.
title_fullStr	To see or not to see: investigating detectability of Ganges River dolphins using a combined visual-acoustic survey.
title_full_unstemmed	To see or not to see: investigating detectability of Ganges River dolphins using a combined visual-acoustic survey.
title_sort	to see or not to see: investigating detectability of ganges river dolphins using a combined visual-acoustic survey.
publisher	Public Library of Science (PLoS)
publishDate	2014
url	https://doaj.org/article/c10507e8b5944abeb1d83d31e83174a4
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To see or not to see: investigating detectability of Ganges River dolphins using a combined visual-acoustic survey.

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