The IUCN/SSC Shark Specialist Group
Shark News 7: June 1996
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Tracking sharks by videocamera -
Crittercam: the video parasite
Ian K. Fergusson, European Shark Research Bureau, UK
'Traditional' methods of telemetry, developed from simple tagging
programmes, have provided shark biologists with a plethora of spatio-temporal,
behavioural and physiological data about their subjects that
have greatly advanced our understanding of these fishes. However,
while telemetry provides important information on the short and
medium term movements and behaviour of elasmobranchs, it fails to
offer the researcher a real-time view of the study animal's second-by-second
behaviour. Thanks to the expanding science of manufacturing
compact, miniaturised video technology, the detailed recording of such
behavioural information is now becoming attainable.
White shark towing Crittercam. Photo: Ian K. Fergusson, 1993.
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One of the most remarkable developments is the Crittercam,
brainchild of National Geographic Television's Greg Marshall.
This camera is designed for parasitic attachment to a shark's (or
other large aquatic animal's) dorsum by means of a corrodable or
other temporary link causing minimal harm to the host's skin. For
sharks, standard stainless-steel Floy darts have been used which are
detached from the camera either by a magnesium wire (which severs
in saltwater after a pre-determined soak-time) or by using an ultrasonic
trigger mechanism. The camera, towed smoothly behind the shark at
about the level of the first dorsal fin, has a forward-looking wide angle
view and records all activity in real time from the moment of
attachment to release (about two hours or full tape duration). As the
Crittercam also contains ultrasonic telemetry gear, the shark can be
tracked, followed by boat and its precise movements mapped by
researchers using a hydrophone, thus allowing the time-coded video
to be continually cross-referenced with its precise location.
Precise details of the Crittercam's construction are confidential,
but a brief description can be provided. The camera housing is
custom-made from metal and synthetics and its contents carefully
configured to provide hydrodynamic stability, perfect balance and
minimal drag. It is compact and torpedo-shaped, containing an
adapted HI-8 Sony camcorder chassis and recorder section powered
by integral battery. The optically corrected semi-wide angle lens films
through a toughened, hemispherical port on the front of Crittercam
and is focused on infinity. The rear of the 'hull' contains ultrasonic
telemetry equipment and a surfacing radio pinger to enable retrieval
of the camera following release from the host. A more extensive array
of data-logging recorders, including those sampling sea temperature,
depth and swimming speed, can be attached to the hull.
The writer viewed Greg Marshall's use of Crittercam on white
sharks off South Africa in 1993-1994 (Fergusson 1995), during the
filming of a co-funded BBC Natural History Unit/National Geographic
TV film, "Great White Shark" (Prog. No. NBS-50-604Y, first transmitted
in the US and UK in March and April 1995). Successful deployments
of the Crittercam system were accomplished at Dyer Island (near
Gansbaai) and Struisbaai, Cape Province. All cameras were recovered
and a number of useful video tape records collected. Full results are
unpublished, but several interesting events were recorded, including
cruising and patrolling behaviour between surface and seabed; short-duration,
opportunistic pursuits of fish and small sharks; and
interactions with other white sharks and cape fur seals Arctocephalus
pusillus pusillus. Topside tracking offered useful information on the
spatial habits of white sharks.
Greg Marshall has revised attachment and retrieval methods. This
work will greatly advance the simplicity and durability of field-use
for both commercial cinematography and research.
Fergusson, I.K. 1995. Great White Lies. BBC Wildlife Magazine, 13
(4): 32-37. April 1995.
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