Artificial reproduction of Holothuria polii: A new candidate for aquaculture

Holothuria polii (Delle Chiaje, 1823) is a common Mediterranean sea cucumber and has recently become a highly exploited target species destined mainly to the Asian markets. Unregulated harvesting is putting the natural stocks at risk, with potential consequences for the benthic communities to which these organisms belong. In response aquaculture, sea ranching and restocking could become solutions to this issue in the Mediterranean region. In this study, we present the first results on artificial breeding of H. polii, describing the spawning induction, larval development and early juvenile growth in hatchery cultures, our goal is to develop a rearing protocol for this species. The trials were conducted between July and September 2016. Holothuria polii was induced to spawn by testing two different methods. The thermal shock proved a simple and effective method for obtaining healthy gametes from this species. Larval development in H. polii progressed through five stages, reaching the pentactula stage in 10 days. Three different microalgal feeding regimens were tested for larval breeding; the higher feeding concentration 20,000-40,000 cells mL(-1) proved to be the best, with 14% of the larvae metamorphosed into settled juveniles by adhering to the artificial substrates at 15 days. Our results indicate that H. polii performs very well in the hatchery rearing during the larval and juvenile phases; this indicates that this species could be a valuable new candidate for aquaculture in the Mediterranean region both for production and for restocking purposes.