2014 Volume 62 Issue 3 Pages 279-287
The sexual maturation and reproductive cycle of the north Pacific giant octopus Enteroctopus dofleini were investigated by regular sampling during the period from November 1989 to May 1997, in the adjacent waters of Tsugaru Strait. A total of 1,113 animals was sampled: 598 males, 515 females. Maturation stages of the animals were classified by the existence and length of spermatophores in males, and the coloration of the ovary in females. Immature specimens of both sexes were taken throughout the year. Maturing male specimens were present from March to December, mature male octopuses appeared between November and May. The minimum size of mature males was 9.8 kg in the mature season, becoming larger from March onwards. Female mature specimens were present from December to May. The minimum mature size in females was 8.5 kg in the mature season, and from January onwards they were almost the same size. The minimum size of copulated females was 10.6 kg in the copulating season (November to April), and from January onwards almost the same size. There were 23 copulated females among 65 mature females (35%).