Optimization of gonad growth by manipulation of temperature and photoperiod in cultivated sea

A starvation and then feeding method was developed to produce about 100% marketable sea urchins, Paracentrotus liÕidus, in 3 1r2 months. This method is needed because the reproduction cycle is desynchronized in the conditions imposed during the somatic growth stage in land-based closed systems. The major advantages of starving the animals are resetting the reproductive cycle Ž . to the spent stage gonads almost devoid of sexual cells and stressing the individuals so that they mobilize and restore the nutritive phagocytes, filling them with nutrients. Batches of sea urchins starved 2 months beforehand were fed ad libitum for 45 days with enriched food under eight Ž . Ž combinations of four temperatures 128C, 168C, 208C and 248C and two photoperiods 9 and 17 h . daylight . In our system, the best combination was 248C and 9 h daylight for growth as well as for Ž . gonad quality. The gonadal indices obtained in dry weight were over 9% at 168C and over 12% at 248C, which are better than what is found in the field for this population. q 2000 Elsevier Science B.V. All rights reserved.