'Exceptional' sighting of grey whale off coast of Italy.

A grey whale was spotted in the Gulf of Naples over the weekend, three days after another sighting in the waters off the island of Ponza, in what is described as an "exceptional event."

Experts believe the whale seen off the coast of Pozzuoli on the evening of 17 April and the port of Baia the next morning, is likely the same animal seen off the Pontine Islands last week, in what is hailed as the "first visit" to Italy by a grey whale.

Regional maritime authorities have dispatched boats to allow for observation of the whale - estimated at eight metres long - while the local coast guard has ordered all ships away from the area to avoid obstructing the whale's journey.

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Noting that grey whales live in the north-eastern Pacific Ocean, between California and Alaska, experts from the Punta Campanella Marine Protected Area say "it remains to be understood how and for what reasons the whale finds itself in the Mediterranean."

"It could be the changing climatic conditions, with the melting of Arctic glaciers, that has caused this incredible migration" - the experts say - stressing that it is essential to report any sighting of the whale, "which appears undernourished and very thin."

In case of sightings, they underline, "remember to keep a distance of about 100 meters, not to interfere with the animal and to contact the authorities immediately, starting with the Harbour Master's Office with the toll-free number 1530."

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The researchers also believe that the sighting of a grey whale off the coast of Morocco in March could be the same specimen.

Grey whales (Eschrichtius robustis), also known as Pacific grey whale, or California gray whale, are found regularly in coastal waters of the North Pacific.

Populations of grey whales off the European coast were wiped out before 500 AD, perhaps due to whaling, becoming extinct in the North Atlantic in the 18th century.

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This makes the sighting of a grey whale off Italy an exceptionally rare event, although it is not the first time one was spotted in the Mediterranean: after centuries of no sightings, a grey whale was seen off the coasts of Israel and Spain in 2010.

Grey whales can measure up to 15 metres long and can weigh up to 40 tons. Photo La Repubblica.