Fin whales, the second largest animal on the planet after blue whales, are represented in the Mediterranean by a resident population separated from the Atlantic.
Fin whales that live in the oceans are known to undergo seasonal migrations between the tropics and high-latitude waters spanning thousands of km.
By contrast, movements of the population of fin whales residing in the Mediterranean are still mostly unknown. During summer, Mediterranean whales congregate in large numbers to feed in the Pelagos Sanctuary in the northwestern Mediterranean, the region’s largest marine protected area designated by France, Italy and Monaco to protect marine mammals. However, their destination during the rest of the year is still a matter of debate. Whales are also known to frequent other parts of the Mediterranean, including the waters near Gibraltar as well as the eastern basin, but their relationship to the whales found in the Pelagos Sanctuary remains unclear.
One of the earliest line transect cetacean survey in the Mediterranean revealed the presence of >900 fin whales in the Pelagos Sanctuary in 1992.
Genetic analyses performed on minute skin samples remotely collected conclusively indicated that Ligurian Sea fin whales are genetically different from their North Atlantic conspecifics.
Through the application by means of suction cups of velocity time-depth-recorders. Depths of at least 470 m were registered, providing evidence of deep diving performances by fin whales in the Mediterranean Sea, never directly recorded for any other species of baleen whales elsewhere.
https://www.tethys.org/activities-overview/research/fin-whales/