Experimental rearing of the sea urchin <italic>Paracentrotus lividus</italic> fed with discards of the lettuce <italic>Lactuca sativa</italic> in a sea‐based system.

Abstract: Small‐sized specimens (test diameter: 16.64 ± 0.93 mm, mean ± SE) of the sea urchin <italic>Paracentrotus lividus</italic> were fed with fresh discards of the lettuce <italic>Lactuca sativa</italic> during a 24‐week experiment in a sea‐based system. At the end of the experiment, stock survival was high (88.8 ± 6.6%). Sea urchin test diameter and total weight grew by 35% and 56%, respectively, while gonad somatic index, after an initial decrease, increased by 3.2%. Moreover, more than 90% of specimens achieved the gonad colour that the market demands. These results support the exploitation of <italic>L. sativa</italic> as the main ingredient in a manufactured diet for echinoculture of <italic>P. lividus</italic>. Employing diets formulated with discard ingredients, combined with a low‐cost sea‐based rearing system, could be a suitable approach for sustainable management of echinoculture. [ABSTRACT FROM AUTHOR]