REPRODUCTIVE CYCLES OF THE RAZOR CLAM ENSIS SILIQUA AND THE CLAM VENUS STRIATULA OFF VILAMOURA, SOUTHERN PORTUGAL

摘要

Annual reproductive cycles of two commercially important bivalves, the razor clam Ensis siliqua and the clam Venus striatula were investigated. Specimens of both species were sampled monthly from a site off Vilamoura, south of Portugal, between June 1992 and May 1993. Gonadal development was monitored using standard histological methods. Observed gametogenic progression was categorized by six stages: (0) inactive; (I) early active gametogenesis; (II) late active gametogenesis; (III) ripe; (IV) partially spawned; and (V) spent. Both males and females showed a synchronism in gonadal development.