Towards the Establishment of a Sea Urchin Sperm Biobank: Key Challenges and Opportunities for the Conservation and Sustainable Aquaculture of Paracentrotus lividus.

The Mediterranean Sea urchin Paracentrotus lividus is a key benthic herbivore and a valuable fishery resource because of the high commercial and gastronomic value of its edible gonads. Increasing market demand, overharvesting, climate change, habitat degradation, and pollution have contributed to the decline of wild populations in several Mediterranean areas. This narrative review, including a preliminary case study, provides an integrated perspective on the role of P. lividus in conservation-oriented aquaculture, with particular attention to Integrated Multi-Trophic Aquaculture (IMTA), microbiological quality, sperm quality assessment, cryopreservation, and germplasm biobanking. IMTA may improve nutrient recycling and resource-use efficiency, whereas cryopreservation and biobanking can support genetic resource conservation, selective breeding, hatchery production, and future restocking programs. Within this framework, the ongoing AVATIM project ("Virtuous Aquaculture in Integrated Marine Multitrophic Aquaculture") is presented as an operational case study illustrating how reproductive biotechnology may be integrated into sustainable multitrophic aquaculture and germplasm conservation strategies. Baseline sperm quality parameters of sexually mature males collected from the southern Adriatic Sea were assessed using Computer-Assisted Sperm Analysis and flow cytometry, providing baseline values for future cryopreservation studies and biobanking applications. Overall, AVATIM illustrates how IMTA, reproductive biotechnology, and genetic resource conservation may jointly support sustainable Mediterranean Sea urchin management.