Subject: Beaked whale biosonar paper
Date: Sat, 18 Sep 2004 14:27:02 -0400
Please be informed that a paper entitled "Beaked whales echolocate on prey"
by Johnson et al. has recently been published in Proceedings of the Royal
Society Letters. See abstract below.
Requests for reprints can be directed to:
Mark Johnson [EMAIL PROTECTED]
or
Peter Tyack [EMAIL PROTECTED]
Please do not reply directly to this message.
Best regards,
Peter T. Madsen
Woods Hole Oceanographic Institution
Beaked whales echolocate on prey
Mark Johnson 1*, Peter T. Madsen 1, Walter M. X. Zimmer 2,
Natacha Aguilar de Soto 3 and Peter L. Tyack 1
1 Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
2 NATO Undersea Research Center, viale San Bartolomeo 400, 19138 La Spezia,
Italy
3 La Laguna University, Tenerife, Canary Islands, Spain
* Author for correspondence ([EMAIL PROTECTED]).
Beaked whales (Cetacea: Ziphiidea) of the genera
Ziphius and Mesoplodon are so difficult to study
that they are mostly known from strandings. How
these elusive toothed whales use and react to sound
is of concern because they mass strand during naval
sonar exercises. A new non-invasive acoustic recording
tag was attached to four beaked whales (two
Mesoplodon densirostris and two Ziphius
cavirostris) and recorded high-frequency clicks during
deep dives. The tagged whales only clicked at
depths below 200 m, down to a maximum depth of
1267 m. Both species produced a large number of
short, directional, ultrasonic clicks with no
significant energy below 20 kHz. The tags recorded
echoes from prey items; to our knowledge, a first for
any animal echolocating in the wild. As far as we are
aware, these echoes provide the first direct evidence
on how free-ranging toothed whales use echolocation
in foraging. The strength of these echoes
suggests that the source level of Mesoplodon clicks
is in the range of 200?220 dB re 1 _Pa at 1 m. This
paper presents conclusive data on the normal vocalizations
of these beaked whale species, which may
enable acoustic monitoring to mitigate exposure to
sounds intense enough to harm them.
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