A turtle in Ajaccio on the French Mediterranean island of Corsica with the plastic pieces it has eaten, before having surgery to remove a hook from its throat.

World - Sea of plastic: Med pollution under spotlight at conservation meet

Plastic packaging and discarded fishing nets bob in the tranquil waters of the Mediterranean, signs of the choking pollution that has stirred strong feelings at the world conservation congress in the French port city Marseille this week.

"The Mediterranean is the most beautiful sea in the world... and one of the most polluted," said Danielle Milon, vice-president of the Calanques National Park on the edge of the city, where the International Union for Conservation of Nature is holding its congress.

While the quantity of rubbish in the sea is well documented—the IUCN released a report on the issue last year entitled "Mare plasticum"—it is driving growing alarm among countries whose economies rely on tourism drawn to pristine beaches and sparkling waters.

At the opening of the IUCN Congress, Greek Prime Minister Kyriakos Mitsotakis and French President Emmanuel Macron pledged to greatly increase the size of conservation areas off their Mediterranean coasts—as well as the rigour with which they are preserved.

"Marine protected areas must no longer be paper parks but must have defined conservation measures," Mitsotakis said at the opening ceremony.

"We must promote sustainable tourism (and) put biodiversity at the heart of tourist coastal planning."

'Noah's Ark'

Near the coasts the main types of plastic pollution in the almost closed sea are packaging and fishing debris, said Francois Galgani, a specialist on maritime waste at Ifremer, a top marine research centre in France.

"Turtles confuse the packaging with jellyfish and in some areas in the Mediterranean 80 percent of turtles have ingested plastic," he said.

Meanwhile, nets can kill long after the fishing boats leaves them behind.

Plastic waste can alter life cycles and the floating debris can even transport some species far from their habitats.

Read more.