The reproductive cycle of the New Zealand venus clam Ruditapes largillierti

The reproductive cycle of the subtidal native New Zealand venerid clam Ruditapes largillierti was studied over a 16-month period in the Whangateau Harbour, northeastern New Zealand. Gametogenic development between males and females was synchronous. Ruditapes largillierti was found to have an annual cycle, with gametogenesis beginning in autumn (March to May), and spawning over an extended period commencing in August and ending in early summer (December). Successful fertilization of gametes was verified by observations of settlement of postmetamorphosed spat onto spat catching bags suspended in the water column in the vicinity of the Whangateau Harbour at the end of the spawning season. The study population was dominated by large adults (45-55 mm shell length). Sex ratios between males and females were equal, and there was no evidence of hermaphroditism. The reproductive cycle described here is similar to other venerid and mesodesmid clams occurring in northern New Zealand.