Correia, Maria JoãoLopes, Patrícia MegaSantos, Pedro M.Jacinto, DavidMateus, DavidMaresca, FrancescoQuintella, Bernardo RuivoCruz, TeresaLourenço, SílviaPombo, AnaCosta, José Lino2023-09-082023-09-082023Correia MJ, Lopes PM, Santos PM, Jacinto D, Mateus D, Maresca F, Quintella BR, Cruz T, Lourenço S, Pombo A, Costa JL. 2023. Pilot studies for stock enhancement of purple sea urchins (Paracentrotus lividus, Lamarck, 1816): usefulness of refuges and calcein marking for the monitoring of juveniles released into the natural environment. Aquat. Living Resour. 36: 12. DOI: 10.1051/alr/20230090990-74401765-2952http://hdl.handle.net/10400.8/8767This study was financially supported through the project “OURICEIRA MAR − Study and characterization of the sea urchin resource in Ericeira and adjacent regions” (PROMAR 31-03-02-FEP-4), funded by the Ministry of Agriculture and Sea and co-funded by the European Fisheries Fund under MAR 2020, and by the Foundation for Science and Technology, through the strategic project UID/MAR/ 04292/2019 granted to MARE (Marine and Environmental Sciences Centre) and the project LA/P/0069/2020 granted to the Associate Laboratory ARNET. The work also received support from the CoastNet Infrastructure (http://geoportal.coastnet.pt).In the framework of stock enhancement, field experiments were conducted between March and July 2021 in rocky shores of Central Portugal to test the usefulness of refuges and calcein marking for juvenile sea urchins releases. Individuals with 10–20mmin test diameter were captured in nature and tagged through immersion in a calcein bath with a concentration of 150 mg L 1, during 48 hr. Artificial shelters were used to provide refuge and an acclimatization structure for the released sea urchins, and in situ monitoring was carried out by counting the marked specimens over three months. Results point out to the importance of using shelters to provide protection to sea urchins, and validated the efficiency of the calcein tagging protocol for in situ monitoring. Sea urchins’ test diameter growth during the experiment was estimated to be 0.470mm month 1 (SD = 0.181).engReseedingSea urchin releaseTaggingSheltersPortugal west coastjournal article10.1051/alr/2023009