39
COROMANDEL LIFE
SUMMER 2014
SHARKS IN THE
SCHEME OF THINGS
For millions of years sharks have been the ring-leaders of the ocean’s
ecosystem; their domination in the food chain has forced fish
populations to evolve schooling behaviour, camouflage and speed
tactics. Without sharks an imbalance occurs leading to a domino effect
throughout the food chain. Riley explains, “The fish that sharks eat will
increase in numbers (for a short time) therefore eating all the smaller fish.
This allows their prey (zooplankton) to explode in numbers, diminishing
phytoplankton numbers. Given that phytoplankton produce around
70% of the world’s oxygen, this is a risky scenario. 400 million years of
stability exists due to sharks, and yet within the last 30 years humans
have reduced shark populations by as much as 98% in some areas”.
For example, a new study says the virtual elimination of large sharks
from the east coast of the U.S. has disturbed the marine ecosystem
and decimated scallops. Co-author of the study and fisheries biolo-
gist at Dalhousie University in Canada Julia Baum states, “With fewer
sharks around, the species they prey upon – like cownose rays – have
increased in numbers, and in turn, hordes of cownose rays dining on
bay scallops have wiped the scallops out.” This has had a disasterous
effect on North Carolina’s bay scallop fishermen.
“
WE’RE” NOT WINNING
BY “THEM” SHARK FINNING
Terrible stereotyping and media hype has led us to believe that we
are part of a shark’s diet. But the opposite is true. According to the
International Shark Attack file, on average only 6 people are killed
worldwide by sharks per year, a miniscule number compared to the 100
million sharks finned every year.
So now you’re thinking…Uh Oh, I don’t eat shark, why are they even
being fished? Throughout Asia, shark fin soup is a delicacy among the
affluent. A combination of rising population and increased wealth has
resulted in an overexploitation of sharks. Since sharks have been on top
of the food chain for so long and have never been victimised by other
predators, the species has evolved to breed at a very slow pace, leaving
the species highly vulnerable to extinction from over fishing.
In the waters
of South
Africa, Riley
Elliott safe on
deck views a
great white.
Right, Riley
catches a
ride with a
whaler shark.
...continued next page
Bodhi
Is a chilled out 2.2m male, very cruisey and in
no rush. He was tagged off Cape Brett in the BOI’s
after which he hung around Three Kings for winter
before heading north for the tropics. Deep diver.
Bluey
is a 2m mature male blue shark and the first
ever satellite tagged in the South Pacific! Bluey was
tagged 50km off the tip of Cape Brett in the Bay of
Islands last summer.
Hannah
had a satellite tag attached to her dorsal fin
as part of a study by PhD student Riley Elliott from
the Univeristy of Auckland. It is hoped she will report
her postion for up to 1 year. Hannah, a 2.5m mature
female blue shark, has navigated north using the
Kermadec Rise.
Riley
Is a 2.5m mature male tagged off Castle Rock
in the Coromandel. He has travelled all over NE NZ
and now is above Vanuatu for a winter vacation, and
will likely return to NZ with the onset of summer.
Kelly
Is a large and strong 2.5 mature male who put
up a good fight when tagged off Castle Rock in the
Coromandel (4km offshore off Hotwater Beach).
Magnus
is a 2.4m mature male tagged off Castle
Rock in the Coromandel who has migrated around
the East Cape rather than north like the other males.
Trooper
is a rugged 2.6m male blue shark who has
been in the wars. While we tagged him off the Bay of
Islands, we cut 4 hooks off him from previous fishing
lines and had multiple scars and wounds.
Cheech
is a 2.2 male who stays under the radar a
lot. Hasn’t given many signals so don’t really know
where he is. Every now and then Cheech will pop up
and say hi.
Meet some of Riley’s
tagged blue sharks
...
Now is the right time to create more awareness leading up to the submission
process. In order to do your bit you can help in the following ways:
• Go to the New Zealand Shark Alliance webpage
and file a submission to the Government. Or sign pledge here:
• Follow the New Zealand Shark Alliance on Facebook.
• Follow Riley Elliott and his shark research on his blog
d Facebook page.
• If you do catch any sharks over the summer, Riley says to “treat it nicely,
pulling it in as close to the hook as possible before cutting the line”.
YOU CAN
HELP
THE
SHARK
BODHI
SETS
WORLD DIVING
RECORD!
Just three weeks after tagging, Bodhi showed his stuff. This 2.5m male
Blue shark dived 1250m off the Bay of Plenty coast. Bodhi is only one
of two of sharks tagged for both location and depth/temperature. The
previous record of 1160m was set by a female Blue in Portugal. Why the
deep dives? “Bodhi was probably chasing squid,” explains Riley, “which
makes up 60% of a shark’s diet.”
