A starvation and then feeding method was developed to produce about 100% marketable sea urchins, Paracentrotus lividus, in 3 1/2 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 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 combinations of four temperatures (12 degrees C, 16 degrees C, 20 degrees C and 24 degrees C) and two photoperiods (9 and 17 h daylight). In our system, the best combination was 24 degrees C and 9 h daylight for growth as well as for gonad quality. The gonadal indices obtained (in dry weight) were over 9% at 16 degrees C and over 12% at 24 degrees C, which are better than what is found in the field for this population. |
