Distribution of Noah’s giant clam, Tridacna noae

Abstract

Previously confused with the small giant clam Tridacna maxima, the recently resurrected Noah’s giant clam, Tridacna noae, has been reported from the Taiwanese and the Ryukyu archipelagoes. Our recent underwater observations now extend its distribution to Dongsha (northern South China Sea), Bunaken (Sulawesi Sea), Madang and Kavieng (Bismarck Sea), the Alor archipelago (Sawu Sea), Kosrae (Caroline Islands), New Caledonia, the Loyalty Islands and Vanuatu (Coral Sea), Viti-Levu (Fiji), Wallis Island, and Kiritimati (Northern Line Islands). Published mitochondrial DNA sequences retrieved from open-access databases also indicate its presence in eastern Negros (Philippines), in the Molucca Sea, at Ningaloo Reef (Western Australia), and in the Solomon Islands. Noah’s giant clam is thus a widely distributed Indo-West Pacific species. Wherever research has been done on small giant clams throughout T. noae’s range, the inadvertent confusion of T. noae with T. maxima might have led to overestimating actual T. maxima densities and to errors in estimating demographic parameters.