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The once abundant Giant Clam, Tridacna gigas, has
become another victim of the illegal practice of dynamite
and sodium cyanide fishing within the national park. Normally
they reach a size of 100+ cm and weight up to 500 kg. Their
habitat is the coral reef to a depth of 15 meters. The local
giant clam population has been so reduced that the PTA-HINP
began a restoration program to increase their numbers.
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The giant clams are bred in the Bolinao Facilities of the
University of the Philippines Marine Science Institute, Diliman.
Only one clam is needed for breeding because they are hermaphrodites,
having both the male and female organs. They are raised for
7 years before being brought to the Hundred Islands.
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The giant clam seldom closes its shell, the mantle (body)
of the clam has two holes, one on top for intake and the other
to exhaust seawater.
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If no suitable substrate is available,
concrete pads are placed on the sea floor for the clams to attach
to. |
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A natural enemy of the giant clams,
this shellfish attaches itself to the giant clam's shell, bores
into the shell and literally sucks the body. |
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A hatchery has been established between
Quezon and Old Scout Islands to eliminate transporting the clams
from Bolinao. Boats and swimming is prohibited near the hatchery
except for the PTA staff who clean the alge from the cages weekly. |
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These cute baby giants are about one year old. The one on
the right is a boy and a girl, so it the one on the left.
To date 3,000 giant clams have been replaced, this is from
the goal of 10,000 clams.
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For those who want to see the giant
clams, a snorkling area has been set-up on the northern side
of Quezon Is. Also a demonstartion area has been set-up
next to the northern pavilion where qualified PTA staff can
show the clams. |
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Another species being replaced is
the Horse's Hoof Clam, Hippopus hippopus, which is also
known as the Bear Paw, Rolling, or Strawberry Clam. It grows
to 45 cm and found in the coral or on a rubble substrate from
the intertidal to 10 meters deep. |
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Since January 2001, there has not
been one instance of dynamiting! This is because some of the
transplanted giant clams were found dynamited which prompted
the authorities to strictly monitor and enforce the anti-dynamiting
laws. |
