Abstract “For more than two decades, the Philippine government has protected the giant clams (Bivalvia: Cardiidae: Tridacninae) from exploitation and trade. However, there still is lack of information on the impact of these protective measures in conserving the species richness and density, especially in Palawan, the country’s last stronghold of these reef-associated bivalves. Hence, to assess the species richness and density of giant clams in Palawan, we conducted 57 photo-transect surveys in six sites covering 12,325 m 2. Out of these transect, 15 measured 5 × 25 m and the rest measured 5 × 50 m. For historical trends in the population of giant clams in Palawan, we used six published papers obtained from online platforms, 13 reports, and five undergraduate theses archived in local libraries. Information derived from recent field surveys indicated high variations in species richness (2 to 5 species) and densities (0.1 to > 3.6 ind.100 m -2). Historical data starting from 1984, including recent fieldwork, indicated very low densities and a declining trend. The current status suggests that giant clam populations’ viability and the reefs’ health are threatened. Effective mechanisms are needed to safeguard and enhance the remaining giant clam populations.” decades Bivalvia (Bivalvia Cardiidae Tridacninae trade However Palawan countrys country s reefassociated reef associated bivalves Hence phototransect photo transect 12325 12 325 12,32 2 1 platforms reports libraries ( 0.1 01 0 (0. 36 3 6 3. ind100 ind 100 ind.10 . -2) 1984 fieldwork trend populations reefs threatened populations. 1232 32 12,3 0. (0 ind10 10 ind.1 -2 198 123 12, ind1 ind. - 19