The gametogenic cycle of Octopus vulgaris (Mollusca: Cephalopoda) as observed on the Atlantic coast of Andalusia (south of Spain)

The present study reports the gametogenic cycle of the common octopus, Octopus vulgaris Cuvier, 1797 in the Atlantic coast of Andalusia between May 2001 and May 2002. A total of 673 specimens of total weight ranging from 30 to 3,732 g were analysed. The gonad development was defined by means of histological methods and gonadosomatic indexes. Four gametogenic stages were identified in males (I immature, II maturing, III mature, IV spawning) and in females (I immature, II maturing, III pre-spawning, IV spawning). The sex ratio obtained was not significantly different from 1:1 (P>0.01). Mature males were found during the whole year, September being the month when the highest rate of sexually active individuals occurred (48%). In females, the gametogenic cycle commenced in December and ended in November, and spawning occurred between April and October, with two maximum peaks in August and September (48% in each). Size at sexual maturity was 850 g of total body weight for males and 1,250 g of total body weight for females. Males mature earlier than females.