The crocus clam Tridacna crocea, one of the seven known giant clam
species in the Philippines (Poutiers 1998), is widely distributed in the Indo
Pacific Region but is possibly extinct in Guam and Northern Mariana Islands
(IUCN 2014). In the Philippines, the exploitation of all giant clam species is
prohibited under Fisheries Administrative Order No. 208, series of 2001 (DA
2001). However, illegal exploitation of giant clams in many parts of the country has greatly reduced natural stock populations (Gomez and Mingoa Licuanan 2006; Gonzales et al. 2014; Picardal and Dolorosa 2014), and only in marine protected areas such as Tubbataha Reefs Natural Park (TRNP) where high densities (100-220 ind.100 m-2) of T. crocea (Calumpong and Cadiz 1993; Ozoa 1995; Dolorosa and Schoppe 2005) have been reported. Methods to quantify the abundance of this species involved the use of either belt transect with 1 x 1 m quadrat placed every 10 m or 2 x 100 m belt transect. No data are so far available on the density of T. crocea embedded in coral rocks exposed at low tide.