Giant clams (Mollusca: Bivalvia: Tridacninae) in Singapore: History, research and conservation

Abstract

This review presents the history of giant clams (S.F. Tridacninae) in Singapore as derived from artifacts, primary and grey literature, museum collections, and anecdotal evidence. Archaeological finds from the 14th century include giant clam valves of at least two species: Tridacna crocea (Lamarck, 1819) and T. squamosa (Lamarck, 1819). An 1847 publication lists T. gigas (Linnaeus, 1758) in Singapore, a species that is absent from later inventories. Hippopus hippopus (Linnaeus, 1758) and T. maxima (Röding, 1798) also used to be found on the reefs surrounding Singapore's Southern Islands, bringing the total number of recorded species to five. Early literature describes how inhabitants of 19th century Singapore relied heavily on fishing and collection of shells for food and trade and that this activity was already impacting clam stocks. Exploitation was probably the main cause of giant clam decline until the 1960s when intense coastal development became an additional contributor. Contemporary surveys of 29 reef sites show very low densities of T. crocea and T. squamosa and a complete absence of H. hippopus, T. gigas, and T. maxima. Very little research was conducted on giant clams in Singapore until 1998 when a mariculture project was initiated. This was succeeded by a programme of basic research that produced papers on mariculture, behaviour, shell morphology, reproduction, and conservation; here we present an outline of some of the more important findings. Finally, we discuss conservation strategies designed to ensure that giant clams will not disappear from Singapore's reefs altogether. © National University of Singapore.