[MARMAM] New publication on investigating the detectability of Ganges river dolphins using a combined visual-acoustic survey

Nadia Richman nadia.richman at ioz.ac.uk
Fri Aug 29 00:34:44 PDT 2014


We are pleased to announce the recent publication of our paper:

Richman NI, Gibbons JM, Turvey ST, Akamatsu T, Ahmed B, Mahabub E, Smith
BD, Jones JPG (2014) To See or Not to See: Investigating Detectability of
Ganges River Dolphins Using a Combined Visual-Acoustic Survey. PLoS ONE
9(5): e96811.


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.

A PDF can be downloaded here

or requested from the corresponding author nadia.richman at ioz.ac.uk

Kind regards,


*Nadia Richman - **PhD Student*
*Institute of Zoology, Zoological Society of London, *

*Regents Park, London, NW1 4RYweb: www.zsl.org/nadiarichman
<http://www.zsl.org/nadiarichman>tel: 0207 449 6324*
*and *

*Bangor University, *

*School of Environment, Natural Resources and GeographyDeiniol Road, *
*Bangor, *
*Gwynedd, **LL57 2UW*
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.uvic.ca/pipermail/marmam/attachments/20140829/8b385ff8/attachment.html>

More information about the MARMAM mailing list