Year-round captive spawning performance of the sea urchin Paracentrotus lividus: Relevance for the use of its larvae as live feed

Field Studies describe echinoplutei not only as grazers but also as prey of naturally occurring fish and shellfish larvae. This finding suggests their potential as live feed in aquaculture. This paper reports oil consistent spawnings of the captive sea urchin Paracentrotus lividus (Lamarck 1816) (Echinodermata: Echnioidea) throughout the year using diets of plant origin (yellow maize and/or dried seaweed) with fixed environmental conditions equivalent to field conditions during late spring (14 h of daily illumination and 18 degrees C of temperature). Broodstock maturation without unwanted spontaneous spawnings was achieved in two ways: extending the natural season of reproduction and inducing out-of-season wild specimens to mature. Controlled spawnings of captive sea urchins were induced every month of the year by KCl 0.5 M injections. The diet maize/seaweed combination gave the best results (79% of the tested urchins) in terms of consistent large spawnings throughout the year, followed by the pure maize diet (50%) and the pure seaweed diet (36%). When out-of-season wild sea urchins were induced to maturation, the majority (72%) of tested individuals required at least 60 clays to spawn under KCl injection when fed the combination diet. The results demonstrate the feasibility of producing larval P. lividus in that high numbers of fertilized eggs (up to 5 million per female) call be obtained year round. The main limitation of exploiting P. lividus as planktonic feed seems to be the mortality of broodstock after injection with 1 ml KCl 0.5 M, which prevents reutilization. The 1-month post-injection survival rate was 30 +/- 8% (mean SE). All surviving sea urchins spawned again after re-injection 1 month later, with a 1-month survival rate of 29%.