The present study was carried out to determine the spat efficiency in the pearl oyster (Pinctada radiata, Leach, 1814) in surface and bottom water at Karantina Island (Izmir/ Turkey). Polyethylene mesh bags were used as collectors. An annual average of 175.16 +/- 11.32 spat m(-2) was obtained from PSC (placed surface collectors) and 82.65 +/- 3.89 spat m(-2) was obtained from PBC (placed bottom collectors). The largest number of new spat attachments occurred in August, both on PSC and PBC: 44 +/- 3.46 and 26 +/- 2.88 spats were found respectively in the outer and inner mesh bags of PSC, and 33 +/- 5.77 and 48 +/- 6.92 spats were found respectively in the outer and inner mesh bags of PBC. New spat attachments (10 mm) continued throughout the study period, except April and May. Adult pearl oysters (50 mm) were found in May. There was a significant difference between PSC and PBC in the total number of spat attachments, the monthly spat attachments and the first spat attachments (p < 0.05). The total number of new spat attachments was positively correlated with temperature and chlorophyll a for both depths (p<0.05).