[MARMAM] sperm whales and airguns

Peter Teglberg Madsen peter.madsen at biology.au.dk
Sun Jun 7 11:49:03 PDT 2009

Dear All,
On behalf of Dr. Patrick Miller and the rest of the co-authors I am pleased
to draw your attention to a recent paper in Deep -Sea Research on controlled
exposure experiments with airguns and Dtagged sperm whales.

Using at-sea experiments to study the effects of airguns on the foraging
behavior of sperm whales in the Gulf of Mexico

P.J.O.Miller, M.P.Johnson, P.T.Madsen, N.Biassoni, M.Quero, P.L.Tyack

Acoustic exposure and behavior of 8 sperm whales were recorded with acoustic
and movement-recording tags before, during and after 5 separate 1–2h
controlled sound exposures of industry-provided airgun arrays. None of the 8
whales changed behavioral state (7 foraging, 1 resting) following the start
of ramp-up at distances of 7–13km, or full array exposure sat 1–13km.The
most closely approached whale rested throughout exposure but started a
foraging dive shortly after the airguns ceased, possibly indicating a delay
in foraging during exposure. Using visual tracking and dead-reckoning of
tagged animals, we found that their direction-of-movement was random with
respect to the airguns, but correlated with the direction-of-movement just
prior to the start of exposure, indicating that the tested whales did not
show horizontal avoidance of the airguns. Oscillations in pitch generated by
swimming movements during foraging dives were on average 6% lower during
exposure than during the immediately following post- exposure period, with
all 7 foraging whales exhibiting less pitching (p ¼ 0.014). Buzz rates, a
proxy for attempts to capture prey, were 19% lower during exposure but given
natural variation in buzz rates and the small numbers of whales, this effect
was not statistically significant (P ¼ 0.141). Though additional studies are
strongly recommended, these initial results indicate that sperm whales in
the highly exposed Gulf of Mexico habitat do not exhibit avoidance reactions
to airguns, but suggest they are affected at ranges well beyond those
currently regulated due to more subtle effects on their foraging behavior.


Reprints can be requested from Patrick Miller: pm29 at st-andrews.ac.uk
Peter T. Madsen

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