ad hoc Report on the SCAR Group on

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Polarforschung 72 (2/3), 69, 2002 (erschienen 2004)
Report on the SCAR ad hoc Group on
Marine Acoustic Technology and the Environment Workshop,
September 2001
by Philip E. O'Brien*'
The Scientific Committee on Antarctic Research (SCAR)
sponsored a workshop on the impact of acoustic technology on
the Antarctic marine environment in Cambridge, September
2001. The participants represented a spectrum of expertise
from biologists specializing in the affects of noise in the
marine environment, biologists specializing in Antarctic animals to geophysicists with knowledge of underwater acoustics. The workshop focussed particularly on the Antarctic and
its finding will be published as a SCAR report after review by
a panel of experts.
Equipment using sound waves to investigate the sea bed and
the water column are essential to the understanding of the
Antarctic marine environment. At the same time, there is
active research into the effects of such technology on marine
animals, particularly cetaceans. The potential risks posed by
equipment are a combination of source level, frequency and
local effects that define the likelihood of interacting with
animals. Many acoustic instruments are of sufficiently low
power and high frequency as to pose a minor risk to the environment. The equipment with the highest risk potential are
airgun arrays and low frequency, high power transducers with
wide beam angles. Cetaceans have been observed avoiding
powerful, low frequency sound sources and there is now a
documented case of injury to whales from multiple, mid
frequency (2.6-8.2 kHz) military echo sounders. At the same
time, some whale populations co-exist with commercial
seismic exploration surveys. In the case of other animals, there
is some evidence for short-term displacement of some seals
and fish by seismic surveys but there is little literature available.
research into sound propagation conditions around Antarctica. Records of the locations, timing, duration, frequency, and
nature of hydro-acoustic and other activities should be
maintained to permit retrospective assessment of the likely
causes of any future observed changes in the distributions,
abundance, or productivity of the potentially affected species
and populations. Some mitigation strategies in use are:
(I) Use of the minimum source level to achieve the result.
(2) Use of "soft starts" whereby power is increased gradually
over periods of 20 minutes or more.
(3) Care should be taken with line layouts to avoid restricting
animals' ability to avoid the source.
(4) Equipment should be shut down if cetaceans are observed
within a distance of the vessel defined by the source power,
directionality and propagation characteristics.
(5) Surveys should be planned to minimize repeated surveying of areas in consecutive years with high risk equipment.
(6) Care should be exercised to minimize impacts in known
sensitive areas and times.
Further research is needed to assess whether these measures
work and to better monitor the proximity of wildlife to a vesseI. The Antarctic community and pennitting agencies will
need to monitor research progress to ensure practices are up to
date.
The working group feIt that the evidence available did not
justify a ban on seismic surveys or scientific echo sounders in
Antarctic waters, however, surveys should be examined on a
case by case basis and mitigation strategies should be used to
reduce the risk to Antarctic wildlife from high power, low
frequency sources. Acoustic releases and similar low power,
occasional source were not considered a threat to wildlife.
Mitigation strategies should be investigated to evaluate their
effectiveness and there should be a regular review of mitigation strategies and the progress of research in the field to
ensure that new research findings will be available to the
Antarctic community. Research into the hearing and reaction
to noise of Antarctic animals should be encouraged as should
* Chief Offieer, SCAR Geoseienee Stancling Seienee Group
I
Gcoseienee Australia, GPO Box 378, Canberra, Australia, 2601.
69

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