REPRODUCTION OF THE SHRIMP PENAEUS-OCCIDE NTALIS (DECAPODA, PENAEIDAE) IN THE GULF OF NICOYA, COSTA-RICA

Reproduction of the shrimp Penaeus occidentalis was studied from June 26 through July 27. 1992 near Curazao beach, Isla Chira, Golfo de Nico ya, Costa Rica. This is the first documentation of reproduction of a p enaeid shrimp in Golfo de Nicoya. Spawning behavior was divided in fiv e stages based on these observations, and sperm-egg interaction was ev aluated with the in vitro spawning technique. Spawned eggs presented a cortical reaction during the first 30 min after being released, and s perm experienced primary binding to egg vitelline envelope. but an acr osome reaction was not activated. There appear to be differences in fe rtilization mechanisms between open and close thelycum penaeid shrimps . Wild P. occidentalis males presented heavy spermatophores compared t o other open thelycum shrimps. Sperm count (49.52 million per compound spermatophore) and sperm abnormalities (22.0 %) were similar Lo those of wild P. setiferus from the Gulf of Mexico.