“These springs are here
because of the bauxite
plateau and believe it or not
this stuff, bauxite, is critical to the
existence of the speartooth sharks,” he
says, crouching down and opening his
water bottle to pour it onto the bauxite
resting on the surface, which sucks down
the water instantaneously.
“As you can see it’s like a giant geological
sponge and the water that comes out
here has been studied and it’s almost as
pure as you can get … virtually no mineral
content. The local indigenous people
have a story that the bauxite plateau is
the belly of the storm woman, and gives
birth to the springs to feed the river, so no
males are ever allowed to touch the water
at the springs.”
It’s this water, he explains, when it meets
the Wenlock, that ensures the speartooth’s
survival.
“No one has ever caught an adult
speartooth shark anywhere so we don’t
know where they live and the Wenlock
River is the only river in Queensland where
baby speartooth sharks occur. We’ve
caught a couple of sub-adults in the
Ducie River which is right next door but the
babies, the juveniles, still have umbilical
scars when you catch them which is cute,
and they are only inhabiting the zone in
the river where the freshwater meets the
salt.
“So you can imagine a mixing happens
and it’s usually really filthy water, really
turbid water - they don’t like it too salty
and if the water is too clear we think they
can’t compete with bull sharks. Speartooth
sharks are really adapted for hunting in
dirty water, they require that salinity that’s
just right – it’s about 2 to 16 parts per
thousand - so these springs are obviously
critical for creating that freshwater inflow.
“If you didn’t have the springs there
wouldn’t be any speartooth sharks, so in
river s north or south, they’re just not there.
Lakefield National Park had one recorded
there from 1983 and another hasn’t been
found since.”
Barry says he’s sure some crocs take a few,
but there’s plenty of slower catfish around
to keep the crocs fed, plus the speartooth’s
enormous number of electro receptors are
thought to make a big difference for the
species.
“It hasn’t been scientifically proven but
you know sharks have electro receptors on
their heads to help them hunt in dirty water
so they can sense electrical currents from
movement, well a bull shark has about 270,
and these speartooth sharks have nearly
700, so we think that lets them hunt in really
filthy water.”
Barry leads the way back to the red-dust
covered 4WD, along the way pointing
out more hidden treasures amongst the
rough – a spiky plant with edible fruit that
tastes like sarsaparilla, a leafy bush which
has stems perfect for paintbrushes, and a
towering Ironwood, which has the hardest
timber of any tree in Australia and of which
every part is poisonous, with rough bark
resembling crocodile skin to no doubt
boast of its toughness and ability to survive
the centuries.
With current speartooth numbers estimated
to be just 2500 in existence, it’s Barry’s aim
that his research will help towards the
speartooth shark also withstanding the test
of time.
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