ON THE BIOLOGY AND MARICULTURE OF GIANT CLAMS

Giant clams, bivalves of the genera Tridacna and Hippopus, are found throughout the tropical Indian and Pacific Oceans. However, their numbers have declined, as they are both edible and attractive, and are thus supplied to Asian food markets and the global marine aquarium trade. Various environmental insults have had negative effects on populations, as well.

For these reasons, over the last few decades several mariculture facilities have reared these clams, in an effort to ameliorate collection pressures on wild populations, and to re-stock areas where over-collection and environmental changes have reduced their numbers.

From a mariculture point of view, these bivalves are unique in that they derive a large portion of their nutritional needs via a symbiotic relationship with internal populations of protists of the genus Symbiodinium. Commonly called zooxanthellae, these protists can provide hosts with over 100% of their daily needs for carbon and energy, while other nutrients can be acquired from the environment by other means. Thus, giant clams can be reared without the use of feeds or other nutritional supplements. However, giant clams grow relatively slowly, and several years may pass before income can be generated by mariculture operations.

This presentation will provide an overview of the basic biology of giant clams, with an emphasis on nutrition, and the methodology of giant clam mariculture. Scalability and temporal issues, and inland aquaculture versus mariculture will also be discussed.