Mediterranean cetaceans constitute a unique assemblage of species found in the virtually closed basin of the Mediterranean Sea. This assemblage differs from those found in the North Atlantic or the Red Sea. In the Mediterranean, cetaceans are represented by around twenty species, but only eight of these are considered common: the Short-beaked dolphin, Common dolphin, Bottlenose dolphin, Risso's dolphin, Long-finned pilot whale, Cuvier's beaked whale, Sperm whale and Fin whale. Their distribution varies greatly from region to region, and their abundance and diversity seem to be greatest in the Corso-Liguro-Provençal basin, where cetaceans have been protected by the Pelagos Sanctuary since 2002. Renowned for their intelligence, which in some respects is similar to that of humans, cetaceans are the focus of protection measures that are all the more important given that their slow life cycle makes them vulnerable to the many threats that affect them in the Mediterranean. Indeed, the density of human settlement and traffic in the Mediterranean basin exposes marine species, and particularly large marine mammals such as cetaceans, to numerous threats that require specific conservation measures.
Situation
Geography
The Mediterranean Sea is a quasi-enclosed sea, divided into four main basins: the Western Basin, the Adriatic Sea, the Central Mediterranean and the Eastern or Levantine Basin – each in turn subdivided into secondary seas. The Mediterranean is known as a very oligotrophic sea, i.e., low in nutrients (and even more so in the eastern basin): only two major rivers flow into it (the Rhone and the Nile), and its weak current limits the circulation of nutrients, particularly nitrates and phosphates. As a result, phytoplankton levels are low, and the pelagic ecosystem is less dense than in other oceanic regions. This explains why cetaceans, and whales in particular, are mainly found near rivers and outlets (Alboran Sea, Aegean Sea) and in areas where deep currents resurface, such as the Ligurian Sea. Bordered by 23 Mediterranean countries with a coastal population of 150 million, the Mediterranean is the world's leading tourist destination and one of the planet's main commercial shipping lanes, handling a quarter of the world's commercial traffic and a third of its oil traffic. As a result, pollution and nuisance are high, and collisions between ships and cetaceans are commonplace.
History Cetaceans, and dolphins in particular, have been familiar to Mediterranean populations since antiquity. They are depicted in bestiaries, as well as in mythology, and appear as early as the 2nd millennium BC on the frescoes of the Minoan palace at Knossos, Crete. The philosopher Aristotle, in the 4th century B.C., devoted lengthy studies to cetaceans, establishing that they are indeed air-breathing mammals that incubate their young with a placenta before nursing them. Several other naturalists, such as Pliny the Elder, have provided very detailed descriptions and numerous anecdotes concerning these animals, attesting to their assiduous frequentation and mutual curiosity. In particular, dolphins enjoyed a very positive image in seafaring civilizations such as the Greeks and Romans: a constellation was named after them, they were seen as cheerful companions of sailors, and it is said that they sometimes rescued shipwrecked sailors, as did the poet Arion of Methymne. Whales, on the other hand, are less familiar to sailors and more intimidating, inspiring fear above all on account of their oversized mouths, and most mentions of them in ancient literature tell stories of devouring by the terrifying monster ketos/cetus (like Jonah in the Bible or Lucian of Samosata in his True Stories), a theme much taken up in both the Middle Ages and the Classical period and which we encounter right up to the 19th century with the story of Pinocchio. Some archaeological data suggest that cetaceans may have been hunted and consumed during the Roman period, but this seems to have remained fairly localized, and there is no historical record of significant fishing of these animals in the Mediterranean (unlike the Atlantic, where the Basques, for example, hunted cetaceans intensively as early as the Middle Ages). Mediterranean whales are essentially rorquals ("skinny" whales): during the most intense period of industrial whaling (late 19th and early 20th centuries), right whales (cold-water whales, for their blubber) were the main target, so this activity had less impact on the Mediterranean basin. However, several species disappeared from the Mediterranean during historic times (notably the harbour porpoise and the grey whale), and it is still difficult to determine the exact causes and mechanisms leading to these disappearances.
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