Reproductive periodicity in the indigenous oyster Saccostrea cucullata in Sasa Bay, Apra Harbor, Guam

Abstract

The population of Saccostrea cucullata (Born) in Sasa Bay had low level continuous reproduction with three main peaks throughout the year, in November–December, March–April, and late June. Gametogenic cycles were 3–4 months in length. The periods of gonadal development and regression were similar for both sexes. Partial spawning with resorption of unspawned gametes generally occurred. Changes in water temperature, salinity, turbidity and climatological parameters were not correlated with spawning. Peaks in spat collection followed peaks in gonad ripeness by 3 wk to 1 month, indicating the length of the planktonic larval period. There were significant differences in the abundance of spatfall between sites but not between collector types. Metamorphosing larvae preferred concave over convex surfaces. Oyster larvae were a major component of bivalve larvae taken in zooplankton tows.