GROWTH, REPRODUCTION AND LIFE-SPAN OF SEPIA-OFFICINALIS (CEPHALOPODA,MOLLUSCA) CULTURED THROUGH 7 CONSECUTIVE GENERATIONS

Hundreds of Sepia officinalis were hatched and cultured through the li fe cycle in each of 13 populations. Two genetic lines were maintained: one for an unprecedented seven generations and another presently in i ts fourth. All generations-save one-produced animals in excess of 1.0 kg body weight. Seven of eight generations with adequate data records had mean weights of 1-2 kg, and the largest cuttlefish reared were a m ale 2.6 kg and a Female 2.9 kg. Fecundity levels were high, but there was a trend towards decreased fertility in later generations, with fer tilization rates dropping below 10%. In the 7th generation, most matur e animals failed to engage in agonistic courtship and mating behaviour . Almost no normal eggs were laid and none was fertile, thus ending th e lineage. Most culture took place at 20-24 degrees C and temperature generally explained variations in life span duration: being of shorter length at higher temperatures. Life spans were consistently longer at 20 degrees C and sizes were greater than predicted from previously pu blished literature. In both lines there was a trend towards larger ind ividuals and longer life spans in subsequent generations. Survival of hatchlings typically exceeded 90% for two months posthatching, and sur vival averaged 50% or higher to sexual maturity when corrected for ani mals removed from the populations for experimental use.