Research
Tagging
Acoustic tags are electronic tags that transmit information on
a particular frequency. This frequency is outside the range of
the animals hearing so it does not disturb them.
Acoustic tags transmit a unique code that can be detected by
listening stations set
on the bottom of the ocean, (these stations record the date and
time a tagged animal is present in the area), or can be used to
follow an animal from a small boat. Sensors on acoustic tags can
also transmit data including swimming depth, swim speed and water
temperature.
Code-swapping the key to acoustic network
The use of acoustic ID tags to trace the movements of marine animals
such as sharks, rays, finfish, and mammals has risen rapidly in
the past few years and the data they gather are being exchanged
by Australian and international scientists.
Acoustic ID tags transmit a unique code at regular intervals which,
when in range, is logged by an electronic receiver or ‘listening
station’ on the seabed, or a hydrophone operated from a vessel.
Animals carrying tags can be detected when in the vicinity of any
such listening station, anywhere in the world.
For example, white sharks tagged off South Australia by CSIRO
have been detected by acoustic listening
stations established primarily
to detect tuna off south-west WA, and grey nurse sharks off the
mid-north coast of NSW.
A network of listening stations is gradually being established
around the southern, eastern and western coasts of Australia, maintained
by various research groups. The effectiveness of this network will
depend on the exchange of data between researchers and by the common
listing of their assigned tag codes.
There is also the possibility of highly migratory species such
as sharks and tuna being detected by listening stations deployed
in other countries such as New Zealand, Indonesia, - South Africa
and the US.
What is acoustic tagging?
Acoustic ID tags can be attached externally or internally. As
well as transmitting a unique, identifying code, they can be fitted
with sensors that transmit a variety of data including water temperature,
swim depth and swim speed.
Acoustic ID tags are commonly used to record the extent to which
an animal uses a particular area, and how this behaviour may change
over time. They are suited to research on any species to which
a transmitter can be attached or implanted without modifying its
behaviour, such as fish, sharks, crustaceans and squid.
Acoustic receivers, or ‘listening stations’, can record
the presence of thousands of animals fitted with acoustic ID tags.
Tagged animals can be recorded visiting a monitored site, such
as the Neptune Islands in SA, or can be tracked over hundreds or
thousands of kilometres by placing multiple receivers in grids
or lines. Tag-to-tag data transfer is likely in future.
CSIRO has fitted acoustic ID tags to more than 30 white sharks
(tagged off South Australia) and plans to continue tagging as opportunities
arise and has plans to tag some 50 more in the next few years.
Listening stations are permanently set at the Neptune Islands.
Satellite tracking, and acoustic tagging in South Australia, along
with tracking and sighting data, suggest that white sharks from
this region move extensively throughout Australian waters. Specific
sites may be revisited on a seasonal or more sporadic basis by
some sharks, but no sharks permanently reside in a particular area.
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Last updated
12/11/08
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