Reproductive cycle of the winged pearl oyster, Pteria penguin (Röding 1793) (Pteriidae) in north-eastern Australia

Abstract

The spawning cycle of the winged pearl oyster, Pteria penguin, was studied at Orpheus Island, north-eastern Queensland to observe seasonal changes in gonad development, mean oocyte diameter and sex ratio over time. A total of 201 oysters were collected over 10 sampling periods, approximately every 5–6 weeks (mean = 20 oysters/sample). Histological analysis of gonads showed that spawning activity occurred mainly through the austral mid-spring to late summer (November to March), when mean monthly water temperature ranged between 27.5°C and 29.4°C. There was a primary spawning peak at the beginning of the spawning season in December, followed by a secondary peak in March. Mean oocyte diameter (µm) was highest during the warmer months, ranging from 31.2 ± 2.4 in November to 36.2 ± 3.2 in March, and sex ratio analysis showed the percentage of females in the population also peaked between 30% and 50% during this period.