38
COROMANDEL LIFE
SUMMER 2014
FRIENDING
THE SHARKS
Who’s the real threat,
man or beast?
BY CLAIRE FITZJAMES
Photography by Mike Bhana
1250m off the Bay of Plenty coast! “It’s unusual for sharks to dive
so deep”. says Riley. “They usually stay in the top layer of water.
It isn’t efficient for a shark to do that unless they’re getting a
reward, so that further supports the idea that he was foraging.”
So what have Riley’s sharks been up to? The only female,
Hannah, stayed alone at the top of the Coromandel since her
presumed mating trip to the Kermadecs
Three of the seven males Bromey, Bluey and Bodhi have headed
north to Three Kings Islands (thirteen islands 55km north west of
Cape Reinga), while the fourth, Riley, has covered some amazing
distances of up to 5000km over a period of 2 weeks, going nearly
as far as Tonga! (Read more p41.)
As of the beginning of November, those same males have been
migrating south back to New Zealand waters via one of the main
highways of the ocean; the East Australian current. Sharks are not
the only fish to get a ride in the current; such currents transport
many schools of fish, squid and plankton.
Not only do these ‘arteries of the ocean’ work as a transportation
service for sharks,
they are rich in photoplankton – oxygen
producing plankton which increases the oxygen levels so vital for
the shark’s survival.
Fascinatingly, for sharks to breathe they need
to move and the oxygen generated in the surf and currents help
sharks to breathe easier and keep moving. This is why some
sharks come to bask in the surf, allowing waves to push the
turbulent oxygenated water through their gills, enabling
them to
save energy.
Riley Elliott
pets the fin of
a blue shark
while a pilot
fish looks on.
Eliott found
the pair at
the back of
Castle Rock
off Hot Water
Beach.
Mako shark between Castle Rock
and the Alderman Islands.
T
HEY CROSS OUR MINDS
when we dip our toes in
the ocean, appear as front page threats in the holiday
headlines and are the topic of debate over summer BBQs
– sharks! This threat, however, is really blown out of proportion,
creating an unnecessary animosity between us and the shark. Do
we really know enough to “judge” these creatures that share the
Coromandel waters with us?
Out of the 470 shark species world wide, only a handful frequent
our part of the South Pacific here in the Coromandel. Bronze
Whalers are the most common larger shark in our waters, moving
into our shallow coastal waters during the summer to feed, have
their pups and to breed. They are nonaggressive fish eaters and
pose little threat to us. Out in the deeper oceans the Blue and
Mako sharks guide themselves through the currents on a quest
for their next meal.
To get a better understanding of local sharks, we talked to
University of Auckland PhD candidate and shark scientist, Riley
Elliott. He operates satellite tagging research out of Hot Water
Beach around the Castle Rock waters. Tags are attached to the
dorsal fin (it is 100% cartilage so the shark is not harmed). Riley
states, “Via satellite tagging, we can follow these animals as they
migrate 1000s of kms and dive to depths greater than 1500m.”
His research has shown the highly migratory Blues will travel
great distances and depths in search of fish and squid. They
typically dive to 400m during the day, and just recently one of
Riley’s tagged sharks, Bodhi, reached a world record depth of
