GROWTH AND LIFE-CYCLES OF THE CUTTLEFISH SEPIA-OFFICINALIS L (MOLLUSCA, CEPHALOPODA) IN SOUTH BRITTANY (FRANCE)

To estimate the growth of the cuttlefish, Sepia officinalis L., in South Brittany, three different types of sampling were carried out. The sizes of individuals caught by commercial trawlers during the entire migratory cycle were examined. Breeding adults and juveniles were captured on the main spawning grounds. Growth varies with the seasons. Its rate decreases during winter and spring. Some cuttlefish breed before they become 1 year old, the majority during their second year of life. All adults seem to die soon after breeding. Therefore. there are two different biological cycles in South Brittany. The group II breeders of both sexes live on the average 22 months post-hatching; their mean size at breeding is about 22 cm. In group I breeders, the average size attained is about 13.4 cm in males and about 14.8 cm in females; their average life-span is about 11 months.