ceans and seas dominate our blue planet, but they are safeguarded much less than the land. Though they cover 72 per cent of the Earth's surface, less than 1 per cent of their area is set aside in protected areas, compared with 12.5 per cent of the relatively small amount of dry land. And two fifths of this 1 per cent lies in just two huge sites, the Great Barrier Reef Marine Park and the Northwestern Hawaiian Islands Coral Reef Ecosystem Reserve.

The vast majority of the world's 4,000 marine protected areas (MPAs) lie close to the coast where they are relatively easy to police, and countries are also in a position to manage their own exclusive economic zones, which run 200 nautical miles out to sea. But nearly two thirds of the oceans lie beyond these, unmanaged and unprotected.

	Millan/UNEP/Topham

Protection is needed to foster biodiversity - including such critical ecosystems as coral reefs, and endangered species like turtles or monk seals - and to help maintain the oceans' productivity. When properly managed, protected areas or no-take zones can work well. To take one example, parts of the Georges Bank, off the United States' east coast, were closed to fishing after overexploitation had devastated stocks. Within five years these had recovered, and fish began to spill over to surrounding fishing areas, dramatically increasing catches.

South Africa has just created four new MPAs to protect a sub-tidal coral reef, shark species under threat, an annual migration of millions of sardines along its coast, and some endangered seabirds. And last year Ireland announced MPAs and fishing restrictions to protect cold-water corals - home to 1,300 species of invertebrates and fish - off its west coast.

But some MPAs exist only in name, and policing is always difficult. Surveillance by guards, air and sea patrols and local communities is now being tightened, and satellite tracking systems will help. Even so, there is a further need for mechanisms to strengthen international protection.