The Mediterranean Sea is home to increasingly rare cetacean populations. These are the eight species of whales and dolphins that can be spotted and discovered in the Ligurian Sea with the Tethys Research Institute.
"Blow at two o'clock!" — with these words, a member of the research team aboard the motor-sailer Pelagos alerts his colleagues, who for five endless minutes have been scanning the sea in attentive silence in search of a white puff: the blow of a male sperm whale surfacing to breathe and rest. The researchers had been following the animal for more than 40 minutes as it hunted in the depths, tracking the impulsive vocalisations (or clicks) it uses as sonar to locate squid in the darkness.
The sighting breaks the boat's silence, triggering a flurry of activity. Everyone has their role: one person photographs the animal's flukes (the tail) to establish its identity, another monitors the rhythm of its breathing, another notes its behaviour, and another records its vocalisations. While these data are collected non-invasively, the sperm whale is almost motionless in the water. With every blow, all those present are left spellbound. After about fifteen minutes, the individual gives a couple of tail slaps, arches its back, lifts its fluke clear of the water — the moment to discover its identity — and departs, resuming its hunt in the deep.
This is a typical day during the research expeditions organised each summer in the Ligurian Sea by the Tethys Research Institute. Non-specialists are offered the unique opportunity to take part, as volunteers, in the day-to-day life of marine biologists, making a valuable contribution to the activities of the non-profit organisation that for thirty years has been one of the leading centres for cetacean research and conservation in Italy and the Mediterranean Sea.
Sperm whales are just one of the eight species that can be regularly encountered in this basin. Some of these are better known than others, but where genetic data are available, the populations inhabiting the Mediterranean prove to be distinct from those living in the nearby North Atlantic Ocean. The Mediterranean Sea is characterised by high levels of biological diversity and endemism (meaning species found only here). Yet it is also one of the marine regions with the highest levels of shipping traffic, pollution, population density, tourism and fishing in the world. The survival of the isolated cetacean populations it supports is therefore threatened on multiple fronts, and basin-wide conservation action is becoming ever more urgent. Here are the eight cetacean species that can be spotted in the Mediterranean.
With a length exceeding 20 metres, the fin whale is the second largest animal ever to have existed on our planet (the largest is the blue whale). Fin whales migrate to the Ligurian Sea during the summer to feed on the large quantities of krill available in this area, which forms the Pelagos Sanctuary. This marine protected area extends over 87,500 square kilometres and is the subject of an agreement for the protection of marine mammals between Italy, Monaco and France.
Thanks to its remarkable diving abilities, the sperm whale can hunt squid at depths of more than two thousand metres, holding its breath and surveying its surroundings with its powerful sonar system. In the Atlantic, social groups made up of females and calves remain at lower latitudes than the males, which migrate to the poles to feed. In the Mediterranean, however, their movements and social dynamics are not yet fully understood.
This small dolphin is the most frequently encountered species in the Mediterranean. It is generally found in large groups and, in summer, its young can often be observed.
Bottlenose dolphins are one of the most iconic dolphin species in the world. They inhabit the coastal waters of most countries bordering the Mediterranean, but are also found offshore.
These large dolphins are characterised by numerous white scars across their entire body, the result of their social interactions. A complex social structure and their tendency to avoid interactions with boats contribute to the limited knowledge we have of these animals.
Long, slow-moving and glossy black, these highly social animals are only apparently calm. In reality, long-finned pilot whales are formidable deep-water hunters, a skill that has earned them the name of "cheetahs of the deep".
Despite its name, this dolphin species has suffered a dramatic decline in the Mediterranean. Overfishing and habitat degradation have contributed to making this animal a rare sight. Today it is often encountered alongside larger groups of striped dolphins.
Probably the most enigmatic of the eight species, the Cuvier's beaked whale is large, has colourful pigmentation and a pair of protruding teeth (in male specimens), and boasts record-breaking underwater abilities. This species is sadly notorious for its sensitivity to human-generated noise (military sonar in particular), which appears to be the cause of numerous mass strandings that have occurred in recent decades.
Translated by Camilla Soldati