Genetic monitoring of the declining European stony sea urchin Paracentrotus lividus from the central Bay of Biscay (Asturias, northwest Spain) and attempts to restore its wild populations

Paracentrotus lividus is a sea urchin with an important ecological role in the Cantabrian Sea ecosystem, where its populations are in severe decline and the regional government has implemented a population restoration strategy with the aim of preserving this valuable marine resource. In this study, genetic monitoring was conducted for the first time in the central area of the southern Bay of Biscay to describe the genetic diversity patterns of P. lividus and to assess the potential impacts of conservation and mitigation actions on the wild gene pool. Genetic analyses were performed using the mitochondrial cytochrome b gene and microsatellite loci. Asturian localities showed significant genetic heterogeneity, possibly due to genetic drift, and seemed to constitute a differentiated management unit with regard to other areas of the species' distribution. The genetic diversity analyses comparing wild samples with those subjected to restoration experiments did not show significant negative effects on restored localities. Sea urchins from hatcheries represented 3.5% of the total recaptured individuals (95% accuracy). Even when low hatchery contributions were detected in this work, the results pointed to the necessity of improving the initial autochthonous breeder genetic pool and the aquaculture strategies applied when restoring wild populations to avoid future unwanted negative effects on wild gene pools.