Tomonari AKAMATSU, Izumi NAKAZAWA, Takashi TSUCHIYAMA and Naoko KIMURA
(2008): Evidence of nighttime movement of finless porpoises through Kanmon
Strait monitored using a stationary acoustic recording device. Fisheries
Science 74(5), 970-975.
Abstract: From March 2005 to March 2006, the presence of the finless
porpoise Neophocaena phocaenoides in the Kanmon Strait, Japan was monitored
using a stationary acoustic event recording device. A stereo acoustic event
recorder (A-tag) recorded biosonar signals as well as sound source
directions, which can be used to count the number of echolocating porpoises
within a distance of 126 m. During 75 days of effective observation, 37
porpoises were detected acoustically. On average, one individual was
detected every two days. Most of the finless porpoises appeared at night,
and no porpoises were observed from 12:00 to 18:00 hours. Shipping traffic
observed using the same acoustic system showed trends opposite to that of
finless porpoise during the daytime. The tidal current did not affect the
presence of the animals (up to 5.2 knots). However, porpoises were suggested
to swim along the current direction. Finless porpoises appeared to be
isolated and used relatively long-range sonar during the observations,
suggesting that the porpoises passed through the Kanmon Strait rather than
searched for prey.
URL:
http://www3.interscience.wiley.com/journal/121429642/abstract?CRETRY=1&SRETR
Y=0
For reprints please contact Tomonari Akamatsu (email:
Kind regards
Sonja
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Dr. Sonja Amoser
Daringergasse 3
1190 Wien (Vienna)
Austria
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