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Abstract

The reproductive cycles of the pearl oysters Pinctada fucata (Gould) and Pinctada margaritifera (Linnaeus) were examined based on 339 and 284 specimens, collected in southwestern Taiwan. Except for the month of December 2002, Pinctada fucata were collected during the periods from March 2002 to September 2003. Pinctada margaritifera were collected over two periods: from March 2002 to November 2002 and from June 2003 to September 2003. Histological observations on gonadal development indicated that Pinctada fucata and Pinctada margaritifera were protandrous hermaphrodites, and both species exhibited different annual cyclical patterns, in which maturity peaked in May and October for Pinctada fucata, and in July and November for Pinctada margaritifera. Both species had two spawning periods a year. The onset of reproduction appears to be regulated by sea surface temperature. For both species, females outnumbered males during the spawning season.

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