Genomics Goes Deeper in Fisheries Science: The Case of the Blackspot Seabream (Pagellus bogaraveo) in the Northeast Atlantic

Recent advances in genomics are an essential contributor to the assessment of fish stocks by providing a fine-scale identification of the species' genetic boundaries. The blackspot seabream, Pagellus bogaraveo, is a commercial sparid distributed across the northeast (NE) Atlantic and the Mediterranean. Within the NE Atlantic, three P. bogaraveo stocks are currently defined: Azores; Atlantic Iberian waters; Celtic Sea and the Bay of Biscay. We used a genotyping-by-sequencing (GBS) approach to better define the spatial scale at which the species occurs in the NE Atlantic. Our findings revealed the existence of an additional genetic cluster in the eastern Atlantic (Gulf of Cádiz) that was not identified in previous studies based on mtDNA or microsatellite data. The combined effect of ocean circulation patterns, complex bathymetry and the existence of local upwelling may play an important role on the retention of blackspot seabream larvae and adults, providing an explanation for the genetic differentiation between the specimens caught off the Gulf of Cádiz and Peniche (Portugal). Results presented here revealed hidden intra-specific genetic differentiation and can inform a finer-scale sampling to determine the new stock boundaries in the Atlantic Iberian coasts.