Info: Noise Pollution and Whales

Michael Williamson (whe_william@flo.org)
Mon, 11 Dec 1994 21:13:37

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Date: Sun, 11 Dec 1994 21:07:38 -0500 (EST)
From: Michael Williamson <WHE_WILLIAM@flo.org>
Subject: Info: Noise Pollution and Whales
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From:	SMTP%"MARMAM@UVVM.BITNET" 11-DEC-1994 15:59:01.60
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Subj:	abstract- Tom Norris
 
Date:         Sat, 10 Dec 1994 18:23:09 -0800
Reply-To:     Marine Mammals Research and Conservation Discussion
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From:         Tom Norris <NORRIS@MLML.CALSTATE.EDU>
Subject:      abstract- Tom Norris
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Norris, T. F.  1994.  The Effects of Boat Noise on the Acoustic Behavior
of Humpback Whales (Megaptera novaeangliae).  Proc.  Acoust. Soc. Am.
(128th Meeting ). 96(5): 3251.
 
ABSTRACT
Real sources of boat noise were experimentally introduced to singing
humpback whales to examine the effects of boat noise on their acoustic
behavior.  Additionally, songs were recorded during opportunistic passes
of large vessels (10-35m).  Humpback whales are good subjects for such a
study because they sing long, predictable, and loud songs that are simple
to record and analyze.    Twelve variables characterizing time-frequency
components of song signals and the structure of song patterns were
compared for periods before and during exposure to boat noise.  Means of
three variables describing durations of units and phrases were significantly
less during boat-pass periods than during control periods for experimental
boat-passes (n = 9).  Means of the nine remaining variables were not
significantly different.  Similar differences in unit durations were
determined for songs recorded during opportunistic passes of large boats
(n = 7).  However, the frequency structure of units also was affected.  The
statistical power (1-;) was > 90% for non-significant variables describing
phrase and theme structure in both experimental and opportunistic boat-
passes.  The power spectra of noise from medium to large boats
overlapped the power spectra of whale song  more closely than did noise
from small boats.  Results indicate that boat noise might affect humpback
whale song structure at the most basic level by altering the rhythm or
increasing the "tempo" of songs, while phrase and theme structure are
probably not affected.  The significance of these effects concerning the
behavioral biology of humpback whales remains uncertain.
 
Tom Norris, Moss Landing Marine Laboratories,
P.O. Box 147, Moss Landing, CA 95039
NORRIS@MLML.CALSTATE.EDU