Antecedentes sobre el ciclo de reproducción de Modiolus capax (Conrad,1837) (Bivalvia:Mytilidae); en la Bahía de La Paz, Baja California, México

Abstract

A research project on the reproductive cycle of the mussel Modiolus capax was undertaken. These line of work was commenced in 1979 as a need sprung from population studies of a benthonic species which might represent a potential resource, with the posibility of being cultured, in the Bay of La Paz; Southern Baja California. The reproductive activity was estimated by means of the histological analysis of the gonads, using a scale of maturity which comprissed seven stages (indiferenciated, starting gametogenesis, intermediate gametogenesis, advanced gametogenesis, spawning and reabsorption). The features for sexual maturity became obvious when the shell reached 30-40 mm length; this being closely related to the season of the year. When considering the male-female ratio (in numbers), it was apparent that the male organisms out-numbered the female ones; during the season of low reproductive activity however, the male-female ratio taken as weight was greater than that of the male counterpart. The reproductive activity of M. capax begins in the Spring. A first spawning period was recorded in April which seems to be related to the rise in the water temperature. Gonadal activity was found to be continuous from spring to early Autumn. A spawning peak was observed in July. The highest frequencies of advanced gametogenesis and spawning activity were recorded in April, July, August and September. In late Autumn and during Winter, it was found that 90% of the population became sexually inactive and the gonads did not display any of their microscopical features and longer. However follicles being reabsorved could be seen.