New plans for the Great Barrier Reef Marine Park ban commercial fishermen from a third of the giant coral network off Australia's northeast coast and tightens restrictions on shipping through the delicate ecosystem.

Environment Minister David Kemp described the plan as an "historic and visionary" initiative that would help protect the reef -- considered by scientists to be the world's largest living organism -- from the ravages of pollution and over-fishing.

Conservationists welcomed the move, but warned that threats to the reef from climate change and land-based pollution still need to be addressed.

The plan expands "high protection zones" from 4.6 percent of the Great Barrier Reef park to covering 33.3 percent of its area.

These so-called "green zones" would be off-limits to fishermen, with only research and tourism allowed. Restrictions on shipping in reef areas were also tightened.

In response to protests from commercial fishing interests, the government last month agreed to a compensation package for those affected. Amounts have yet to be decided.

The Great Barrier Reef, a world heritage listed natural wonder covers more than 345,000 square kilometers (133,000 sq miles) and comprises 2,900 coral reefs, 900 islands and 1,500 fish species.

It is Australia's number one tourist destination, attracting a million visitors a year and generating revenues of more than 2.3 billion dollarsbillion US).

Scientists have warned that the reef is under increasing threat from coral bleaching linked to global warming, pollution from shipping, over-fishing and damage caused by chemical run-off from coastal agriculture.

Kemp said the government's zoning plan, submitted Wednesday to parliament, would help tackle such threats by creating the "largest network of protected marine areas in the world".

The initiative is expected to pass through parliament by late March and take effect in mid-2004, Kemp's spokeswoman said.

The tourism industry and conservationists generally praised the plan, with WWF Australia describing it as a stunning achievement and a win for all Australians.

"The new network of marine sanctuaries will result in very real and tangible benefits for the health of the Reef and its stunning wildlife," said WWF campaigner Imogen Zethoven.

The Australian Conservation Foundation welcomed the plan but stressed that more effort was needed to address other threats to the reef such as pollution and climate change.

Fishing industry officials for their part complained that the new Green Zones were too extensive.

"Disappointingly, there are a whole range of fishing closures which are just unjustified and don't need to be there," spokesman Duncan Souter said.

"The plan itself will still have a devastating effect on hundreds of fishing families up and down the coast," he said, calling on the government to provide figures for its compensation package.

Industy officials have estimated the plan will cost commercial fishing and prawn farming industries around 38 million dollars (28 million US dollars) a year.

SPACE.WIRE