Quarantine Aspects of the Reintro duction of Tridacna gigas to Fiji E. Ledua and T.J .H. Adams* Abstract As part of the re introduction of Tridacna gigas to Fij i, strict quarantine measures we re undertaken to lessen the risk of introduci ng diseases and parasites. Hatchery-gro wn juveniles, rather than adults, were chosen, and were held under rigid quarantine at Dalice on the is land of Makogai. This si te is now used as an a ni mal quarantine and breeding station. The cl ams were moved to ocean-nursery cages after 6 months, and growth and survival have been satisfactory. RESULTS of surveys from 1984- 87 throughout Fiji waters have shown that the largest and most commercially import ant of the species of tridacnids, Tridacna gigas, is no longer found in Fiji. The evidence for its former presence is li mited fi rstly to one reliable report of a live specimen (the shell of which can be seen in Suva) being fished at Wailagilala, a remote atoll in the N or thern Lau Group, during the course of lighthouse maintenance work in 1970, and secondly to the fact t hat there is a Fijian name, vasua matau, a tt ributed to T. gigas. Several other shells can be seen in suburban gardens, but none of these have been traced, although some are rumoured to come from Va tu leJe, a low limestone island with a shallow lagoon to the sou th of Viti Levu. Rosewater (1965) incl ud es Fiji in the geographic range of T. gigas, although without supporting specimens. However, no specimens, alive or dead, have been found in the water during the cour se of Fiji surveys by the ACIAR Giant Clam Project an d it is likely that T. gigas was never particularly co mmon here on the edge of its geogra phical range. Its large size and its probable habitat near the larger islands would make it vulnera ble to exploitation. It will prove instructive in the fut ure to examine the fossil record and shell-middens. • Fisheries Division, Ministry of Primary Industries, Suva, Fi ji . The F ij i Modu le of the ACIAR Giant Clam Project made the deci si on to reint roduce T. gi gas to Fiji in order to have the op tion of eventually mariculturing this fast-growing species. It was considered preferable to introduce hatchery-grown juveniles rather t han adult individuals, to lessen the risk of introducing diseases a nd parasites. The project also considered this a useful test of the feasibility of setting up quaranti ne systems for the reintroduction of giant clams to sma ll Paci fic islands in general. Site The quarantine system is at Dalice on the northeast side of Makogai, a small (9.6 km 2 ) volca ni c island in the Koro Sea. Makogai has an extensive bar ri er reef and Dalice Bay is furth er sheltered by the island of Makodroga to the north. The bay is usually full-salinity, since there is very little freshwater runoff, and water clarity genera ll y good. There are few giant cl ams to be seen in Dalice Bay, as it is comparatively well populated and a good anchorage, but T. derasa, T. squamosa and T. maxima can be found around the island and on the barrier ree f. There are also many fossil tr idacnid shells to be seen along the sh ore, a nd historical shell - dumps on the sout h side of the island. Dalice is the site of a former leper colony, and Makogai is now used as an animal qua rantine and breeding st at ion by the Ministry of Primary Industries. Existing, but in some cases derelict, 237