Mediterranean cetaceans

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.

[5] 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.

[8] Cetaceans, from their scientific name Cetacea (from ancient Greek κῆτος / kêtos, "cetacean"), form an infra-order of aquatic mammals, classified in the order Artiodactyla, where their closest cousins are the hippopotamuses: like all mammals, they breathe air and nurse their young, despite their exclusive adaptation to the marine environment, which has notably caused them to lose most of their hair and their hind limbs.

Some species, such as the harbour porpoise, disappeared in historical times due to human influence, while others, such as the Indian Ocean humpback dolphin (Sousa plumbea),[14] could colonize the area thanks to the Suez Canal.

On larger time scales, many other species that are now extinct or exiled have inhabited this basin, with significant changes in response to geological changes such as the Messinian salinity crisis.

[20] This species is rare in the Mediterranean (mainly reported in the western half, very sporadically[13][14]), and its presence may be largely due to incursions of specimens from the Atlantic, where it is abundant.

They tend to live offshore (45 km from the coast on average), in groups of ten to thirty individuals, sometimes more, throughout most of the Mediterranean basin, with the exception of the Aegean Sea.

Its distribution is very uneven: it is rare in the western basin (virtually absent from the French-Mediterranean coast),[13][17]) and more common in the southern and eastern Mediterranean, particularly in Greece;[14] it is particularly abundant in the Black Sea, where it replaces the Blue and White Dolphin (no doubt due to the relative absence of squid)[30] and is sometimes considered a subspecies (Delphinus delphis ponticus).

[14]The killer whale (Orcinus orca) is the largest delphinid species, easily recognized by its size, which can exceed 8 m in length and weigh nine tons, and its black and white coat.

[14] The Great Sperm Whale (Physeter macrocephalus) is the largest of the odontocetes, measuring up to eighteen meters in length and weighing forty tons (considerably less for females).

[38] Recognizable by its size, angular silhouette and small pyramidal dorsal fin, it is also the largest carnivorous predator of our time, feeding in particular on large abyssal squid, which it will fish at depths of up to 2,000 m after very characteristic vertical probes, with its tail straight out of the water.

[13] In addition, the Indian Ocean humpback dolphin (Sousa plumbea) has been the subject of several recent reports in Egypt and Israel, as it appears to have successfully crossed the Suez Canal ("Lessepsian migration").

[14] Similarly, a pair of Belugas (Delphinapterus leucas), an Arctic species, were mistakenly released in the Crimea in 1991, but the chances of this resulting in a resident population are very slim.

[citation needed] Although they belong to other vertebrate groups unrelated to cetaceans, some of these animals may occupy similar ecological niches, and are often subject to the same threats to their habitats and way of life.

[3] Finally, a number of large fish are also subject to protection measures similar to those for cetaceans, such as the Basking shark (Cetorhinus maximus), the Mediterranean Sea Devil (Mobula mobular), or, closer to the coast, the Brown Grouper (Epinephelus marginatus).

[61] It is estimated that more than ten fin whales die every year in the Mediterranean (eight to forty according to WWF)[64] as a result of ship strikes, and many more are injured or crippled.

[66] Marine pollution is of two kinds: macroelements ("garbage"), which animals can ingest at the risk of suffocating, and dissolved microelements (heavy metals, pesticides, medicines, industrial products, etc.

[67][68] The fact that the Mediterranean is an enclosed sea, closely bordered by highly industrialized, densely populated countries with under-equipped waste management facilities, further exacerbates the situation.

[3] Macro-waste varies enormously in size, from abandoned fishing nets hundreds or even thousands of meters long[57] – a death trap for even the largest whales – to microscopic microplastics suspended in the water.

[64] As far as microplastics are concerned, the Mediterranean is probably the sea with the highest concentration in the world, and WWF France estimates that "Nearly 269,000 tonnes of plastic waste made up of more than 5,000 billion particles float on the oceans".

[69] According to a study by the Pelagic Cetacean Research Institute in Athens, plastic ingestion is the main cause of mortality for sperm whales in the Mediterranean.

[40] All studies carried out in the Mediterranean have shown a worrying bioaccumulation of numerous soluble pollutants in cetaceans, five to ten times higher than that observed in their Atlantic congeners.

[74][75][76] The main sources of noise pollution in the Mediterranean are maritime traffic (very intense and particularly dense in certain corridors such as the Alboran, Aegean and Tyrrhenian seas), but also sonar[77] and certain other telemetry devices, seismic prospecting, underwater drilling, certain oceanographic experiments, military activities, and other acoustic nuisances originating from the coast and propagating in the water.

[80] According to the Groupe de recherche sur les cétacés (GREC), this harassment, which is illegal in French waters, can prevent the targeted animals from feeding or resting.

[81] To prevent any adverse effects on these animals, strict rules govern this activity, which is further reinforced in marine protected areas (MPAs) such as the Pelagos Sanctuary.

Also in 2008, Europe adopted the Marine Strategy Framework Directive, which defines "good environmental status" as the objective to be achieved for EU waters (based on an ecosystem approach).

According to the decree of October 20, 1970, "It is forbidden to destroy, pursue or capture by any means whatsoever, even without the intention of killing them, marine mammals of the Delphinidae family", and according to the decree of July 27, 1995 "are prohibited on national territory, including the economic zone defined in article 1 of the aforementioned amended law of July 16, 1976, and at all times, the destruction, mutilation, capture or intentional removal, naturalization of marine mammals of the following species or, whether alive or dead, their transport, peddling, use, offering for sale, sale or purchase".

[95] The Law for the Reconquest of Biodiversity, Nature and Landscapes, promulgated on August 9, 2016, notably requires in Article L334-2-2 of the Environmental Code the installation of anti-collision devices on vessels over 24 m flying the French flag and regularly sailing in marine sanctuaries.

[99] According to Aichi Target C.11 (adopted by the Convention on Biological Diversity in 2010), the aim is to have at least one tenth of the Mediterranean under significant protected status and with a management plan.

[2] Several regulatory measures exist and depend on the goodwill of the players involved, notably charters, codes of good conduct, certifications, and the adoption of specific procedures or equipment.