| To
Catch a Tiger by the Tail
Text:
Richard Fitzpatrick
Hanging
onto the dorsal fin of a tiger shark as it swims is a truly
awesome experience. Feeling the immense power and strength
of these animals is incredible. Many people think I must
have a death wish because tiger sharks are known to be pretty
aggressive. I have stopped telling people what I do at social
gatherings, it is a guaranteed conversation stopper. “What
do you do?” “I tail rope sharks in the open ocean”.
People either think I am liar or a loony!
I started off working with captive sharks in aquariums around
Australia but eventually left the aquarium world to move
into underwater filming and to pursue my dream to do hands
on research with wild sharks. I teamed up with eco-tourist
venture Undersea Explorer to establish a long-term shark
monitoring program. For the last eight years we have been
studying the shark populations out at Osprey Reef in the
Coral Sea, 60 nautical miles off the north-east coast of
Queensland. Undersea Explorer visits some of the most pristine
and remote reefs in Australia and provides a unique chance
for tourists to interact and work with research scientists.
I run the shark project but there are also projects on Minke
Whales, Nautilus, Coral Monitoring and Water Quality.
Osprey
reef is an ideal dive site and a hot spot for sharks. White
tip reef sharks, Grey Reef Sharks and Silver tips are guaranteed
and hammerheads also seen regularly. To study the sharks
here I need to insert a small id microchip underneath the
skin, and for this I need to bring the shark up to the boat.
This is easier said than done. Even the smaller sharks are
incredibly powerful and quick, so I developed a technique
of underwater shark rodeo! A crate of bait is placed on
the reef and while the shark is preoccupied by the food,
I grab hold of its tail and slip a rope around it. After
that it’s just like walking a dog.
After
working with smaller sharks for a few years I set myself
a new challenge- working with the mighty tiger shark. Reef
sharks are strong, but being the largest tropical predatory
shark, tigers are a whole new ballgame!
Raine
Island in the remote Far Northern end of the Great Barrier
Reef is famous as the world’s largest turtle rookery.
In November it has been known for more than 14,000 turtles
to come ashore to nest here in just one night. Raine Island’s
impressive turtle aggregations are no secret to marine predators
like the tiger shark. As the turtles come in to nest, the
tigers come in to feed.
Very
little is known about tiger shark behavior and I wanted
to find out just how far the tiger sharks were traveling
to feast on the migrating sea turtles at Raine Island. To
do this I needed to be able to track the sharks’ movements
and the best way to do that is from space. I needed somehow
to attach a satellite tag to the dorsal fin of tiger sharks
at Raine Island so that I could follow them once they left
the island.
The
first hurdle was ‘How?’ My initial idea was just
to up scale the existing technique. After all tigers are
just big reef sharks. The saving grace to capturing an animal
of this strength and size is the bizarre way that sharks
behave once their tails are secured. Nobody really knows
why, but the minute the tail is caught they stop swimming
and lie placidly in the water, allowing us to do whatever
we want.
However
until the moment that that tail is secured the sharks is
far from placid! Grabbing the tail of a thrashing three
and a half meter shark is pretty difficult, especially as
the power of the shark turns the water to foam and visibility
becomes almost nil. The only way I could get hold of the
tail was by jumping in the water with the sharks. I managed
to catch four tiger sharks like this, but it was pretty
frightening. Seeing the gaping mouth of serrated teeth over
two foot wide suddenly materializing just inches from your
face is an image that is not easily forgotten.
Not
surprisingly the scientific community eventually decided
that this method was too dangerous and quietly encouraged
me to look in to safer options.
After
a year of development and testing I successfully used my
new safer invention—The Shark Claw’. On the end
of a long pole, the ‘Claw’ is designed to clamp
on to the shark’s tail. I attract the sharks using
a floating bait. Approaching the bait in a small dive tender
the tiger often comes over to investigate. The claw has
to hit in exactly the right place so timing has to be perfect.
When we are close enough - I can grab the sharks tail using
the ‘Claw’ without jumping in the water. The ‘shark
claw’ is attached to a rope and large float which the
shark drags through the water till it stops swimming. This
new technique is much quicker and less stressful for both
the animal and me.
The
most recent and biggest tiger shark I have tagged so far
was a 3.5 meter female, which tag sponsors, Diversion Dive
Travel, named ‘Lola’. The satellite tag is attached
to Lola’s dorsal fin, where a salt water switch activates
the tag every time the fin breaks the surface, allowing
us to track her movements from space for months to come.
The
satellite tags have revealed some fascinating new information
about the lives of tiger sharks. We now know that they do
cover huge distances after leaving Raine Island traveling
in all directions. For shark management this kind of information
is essential to match the most appropriate conservation
plans with the behavior of the species. For most large migratory
species like sharks current marine parks only cover small
sections of their habitat. The shark data suggests that
we must rethink and find more realistic methods to protect
these ocean wanderers.
Lola
with the tag right after she was released
|
Independent
