Giant clams make come back in Philippines thanks to science

November 16, 2008 - 0:0

BOLINAO, Philippines (AFP) -– Marine biologist Suzanne Licuanan leans over the side of her battered blue and white motor boat to collect another bag of her precious cargo -- giant clam sperm. Holding up the bag containing eight liter (14 pints) of the cloudy liquid, she says: ""It looks like buko (coconut) juice, doesn't it.""

The world's largest shell fish weighing up to 230 kilos (507 pounds) and measuring up to 1.4 meters (4.5 feet) in length, the Tridacna gigas was once a common sight in waters around the Philippine islands.
Highly prized for its meat and decorative shell the giant clam had virtually disappeared from the Philippines, fished out by local and foreign fishermen.
Shocked by the depletion of giant clam stocks marine biologist Edgardo Gomez decided to do something about it.
In 1985 when he was head of what is now the Marine Science Institute of the University of the Philippines he began an ambitious program to breed and restock the bays and inlets around this southeast Asian archipelago nation of 7,000 islands.
""It really was a shock,"" he told AFP. ""Giant clams are essential to coral reefs and so it was a race against time to build stock up.""
Licuanan joined the program around the same time, when she was a young marine biologist taking a four-year break in 1986 to complete her PhD on giant clams at Australia's James Cook University. Married to a marine biologist who specializes in coral reefs and with three children she divides her time between her work and being a wife and mother.
On this particular Saturday she was collecting sperm and eggs from clams resting on the seabed off a small island in the Lingayen Gulf, six hours drive northwest of Manila.
Of the 10 known species of clams in the world the Philippines has seven and of that number Licuanan says it is the largest giant clam that is most at risk.
""Saving the giant clam has been a long process that has involved not only breeding and restocking but educating local fishermen that they are worth saving,"" she says.
""Clams form an integral part of a coral reef's ecosystem.
Already reefs and bays in many parts of the Philippines are being restocked with mature giant clams from the project's protected ocean nursery areas off Bolinao in the Lingayen Gulf.
""Sometimes you feel like an expectant mother,"" Licuanan said, tapping a syringe containing serotonin.
""Serotonin is a neurotransmitter that induces the clam to adduct its valves to expel the sperm and eggs,"" she says. ""Sometimes you have to give nature a hand in these things.""
Below the boat divers are busy selecting 20 adult clams ranging in age from seven to 10 years, number them and place them in a circle in less than two meters of water.
The thick shells are scrubbed with a nylon brush before the divers return to the boat to collect their syringes and begin to inject the clams.