The following article concerning passive acoustic detection of Maui's
dolphins has recently been published. PDFs are available from
[email protected]
Rayment W, Dawson S, Scali S and Slooten E. 2011. *Listening for a
needle in a haystack: passive acoustic detection of dolphins at very low
densities*. Endangered Species Research 14: 149-156.
ABSTRACT: Passive acoustic surveys have potential for detecting trends
in abundance and habitat use by rare cetaceans. We deployed commercially
available acoustic data loggers (T-PODs) in 4 harbours on the west coast
of New Zealand's North Island between 2005 and 2008 to investigate the
distribution of Maui's dolphin /Cephalorhynchus hectori maui/ and assess
whether current protection measures are sufficient. A set of decision
rules was developed to minimise the potential for false positive
detections. Over 3211 'T-POD days' of acoustic monitoring, 39 click
trains which satisfied all of our decision rules were detected,
indicating the presence of Maui's dolphins in Manukau and Kaipara
Harbours. Data from the site with the most detections were fitted to 3
models, showing that the number of detections varied temporally (p <
0.001). The models were also used to show to what degree dolphins could
have been present at monitored locations yet remain undetected. The
study highlighted the challenges of passive acoustic monitoring of rare
species, particularly of small delphinids in an environment which is
both physically and acoustically challenging. Nonetheless, we
demonstrated that T-PODs are effective in studies of Maui's dolphin
distribution, that Maui's dolphins are found in North Island harbours
and remain at risk from gillnet bycatch. We make a number of
recommendations concerning acoustic monitoring studies of rare
cetaceans, principally that a thorough understanding of the target
signals and the acoustic environment being monitored is essential for
maximising acoustic detection rates.
The following articles using T-PODs with Hector's dolphins are also
available as PDFs:
Rayment W, Dawson S and Slooten E. 2009. *Trialling an automated passive
acoustic detector (T-POD) with Hector's dolphins (/Cephalorhynchus
hectori/)*. Journal of the Marine Biological Association of the UK 89:
1015-1022.
Rayment W, Dawson S and Slooten E. 2010. *Use of T-PODs for acoustic
monitoring of /Cephalorhynchus/ dolphins: a case study with Hector's
dolphins in a marine protected area*. Endangered Species Research 10:
333-339.
--
Will Rayment
FRST Post-doctoral Research Fellow
Marine Mammal Research Group
Marine Science Department
University of Otago
PO Box 56
Dunedin
New Zealand
phone: +64 3 4798304 (w) +64 21 488961 (mob.)
_______________________________________________
MARMAM mailing list
[email protected]
https://lists.uvic.ca/mailman/listinfo/marmam
