The gilthead seabream, a species of commercial interest that migrates seasonally, does not form independent local populations in the northwestern Mediterranean but instead constitutes a single, functionally connected population on a large scale. Individuals spend the summer feeding in the coastal lagoons of the Gulf of Lion and, every autumn, undertake reproductive migrations of hundreds of kilometers to shared spawning grounds in the open sea, mainly in the Marseille region, but also in areas of the Catalan coast. They repeat this pattern year after year.
