The study investigates the global population structure of the highly migratory Bluefish (Pomatomus saltatrix) and examines the effects of present and past oceanographic barriers to dispersal in the North Atlantic, Mediterranean, Marmara, and Black Sea populations. Using mitochondrial and nuclear DNA as molecular markers, researchers identified three main genetic units: American, Spanish, and Turkish, noting that while Bluefish is panmictic in the northwest Atlantic Ocean, it is not in the Mediterranean Sea. The findings suggest that paleoclimate events, such as interglacial cycles, played a fundamental role in shaping the genetic lineages of this species.