REPRODUCTION AND RECRUITMENT IN PECTEN-MA XIMUS L

Recruitment in scallop, Pecten maximus L., appears to be highly variab le. Analysis of data concerning spawning intensity, larval and juvenil e abundance and the strength of die two-year class, indicates that the sequence maturation-spawning-larval life is the most determinant for recruitment. The goal of the present paper is to elucidate the process es responsible for variability at this level. The principal results, a cquired with experimental rearings and microscopical investigations of the gonad and the emitted oocytes are as follows : i) the emitted ooc ytes, during the spawning season, vary in quality, inducing different hatching successes and larval abnormalities; ii) microscopically, the oocytes show ultrastructural abnormalities linked to the atresia proce ss and variability in lipid content; and iii) the origin of this varia bility is found in the environmental conditions during maturation, spe cially temperature.