The reproductive cycle of the red octopus Enteroctopus megalocyathus in fishing areas of Northern Patagonian coast

The reproductive cycle of Enteroctopus megalocyathus was studied based on monthly diving surveys carried out between July 2004 and June 2007 over fishing areas at San José and Nuevo gulfs (Northern Patagonian coast, Argentine). Spermatophore production and storage and ovary-weight increase followed the trend in sea bottom temperatures, and reached maximum values at the beginning of summer. Mature males were found from mid winter onwards, while a low proportion of females showed spermatangia attached to the distal oviducts from mid spring to mid summer when they attained advanced maturity stages. A low frequency of spawning activity was observed during summer and winter months. There were no significant seasonal differences in the sex ratio. Total body weight (BW) and dorsal mantle length (ML) at 50% maturity were estimated at 1072 g and 135.4 mm for males and at 1613 g and 158.5 mm for females. Potential fecundity ranged from 1429 to 6427 oocytes and the number of fully developed spermatophores storage ranged from 1 to 13. Both, potential fecundity and number of spermatophores were significantly correlated with BW and ML. Although mating and breeding can occur in fishing areas, our results suggest that they are most likely to take place in sites deeper than the fishing grounds. This pattern is discussed considering the temperature-regulated aspects of cephalopods reproduction and the local oceanographic processes occurring in the gulfs.

► The reproductive cycle of the E. megalocyathus in Atlantic Patagonian coast.
► Two spawning periods were detected: one in summer and the other in winter.
► Males reach maturity earlier in the year and at smaller size than females.
► Reproductive output of male and female depend on body weight.
► Most animals would not complete the reproductive cycle in fishing sites.