The Mediterranean fin whale
Fin whales Balaenoptera physalus photographed in the Ligurian Sea. Photos © Tethys Research Institute.
The fin whale (Balaenoptera physalus) is the commonest large whale species in the Mediterranean Sea, found mostly over deep, offshore waters of the western and central portion of the region. It is less frequent elsewhere, but present throughout the region. Genetic analyses indicated differences between the Mediterranean population, thought to be resident, and North Atlantic fin whales.
No population estimates exist for the entire region. Line-transect surveys in 1991 and 1992 yielded fin whale population sizes in excess of 3,500 individuals over a large portion of the western Mediterranean, and of about 900 individuals in the Corsican-Ligurian-Provençal basin.
Found in deep waters (400-2,500 m depth, most commonly at the deepest end of the range), offshore of the continental shelf edge. Fin whales in the Mediterranean can also occur in slope and shelf waters, favouring upwelling and frontal zones with high zooplankton concentrations.
Fin whales are regularly encountered throughout the western and central basins, with seasonal summer concentrations in highly productive portions of the Corsican, Ligurian, Tyrrhenian and Ionian Seas, where they feed on euphausiid species, particularly Meganyctiphanes norvegica. During winter, fin whales disperse from these areas to a wider range within the Mediterranean, possibly southwards. They are extremely rare in the Adriatic and Aegean Seas, and in the Levant Basin.
Mediterranean fin whales face a number of actual and potential anthropogenic threats, including collisions with vessels, chemical and acoustic pollution, entanglement in fishing gear and disturbance by boats. Collision events are common in Mediterranean waters and may represent a major cause of non-natural mortality for fin whales. In fact, fin whales are the species most commonly struck by vessels worldwide.
Appropriate habitat use and distribution studies to describe fin whales’ habitat preferences and identify critical habitats are needed to define management measures, particularly with regard to naval traffic, fishing and whale watching.
For more information on Mediterranean fin whales see: