Study on reproductive biological characteristics of Pteria penguin (Roding, 1798) from Khanhhoa to Binhthuan coastal waters [Nghiên cứu một số đặc điểm sinh học sinh sản của Trai Ngọc Nữ Pteria penguin (Roding, 1798) vùng biển Nha Trang – Phan Thiết]

Abstract

Between 25-30 Pteria penguin individuals were randomly collected each month in the coastal waters from Khanhhoa to Binhthuan for studying on reproductive characteristics. The samples were collected from March to October 1999 and January 2000. The results showed that P. penguin in the studied areas is able to spawn from January to October, but the main spawning season lasts from April to August. The first sexual maturity of P. penguin is reached at the average shell height group of 120 mm, corresponding with total weight of 160 gram. The natural sex ratio varies widely with variation of the size. In the total number of samples analyzed, larger individuals (>120mm) contained a higher percentage of females, while smaller individuals (<120mm) tended to contain a higher percentage of males. The hermaphroditic individuals were observed during the study. The absolute and relative fecundity of P. penguin female varies widely with size and ranges from 10,442,622 to 161,793,737 eggs/female and 130,282 to 425,772 eggs/gram total weight, respectively.