A bid to prevent the Turnbull government reducing environmental protection in Australia's national marine parks has failed after Labor and the Greens were unable to secure Senate crossbench support.
Separate disallowance motions to block the government's plan to increase commercial fishing and other activities in the 3.3 million square kilometres of protected offshore regions lost 29 votes to 36 on Thursday.
"The plans strike the right balance between conservation, recreation and economic development and are based on a balanced, scientific and evidence-based approach to marine park management," Environment and Energy Minister Josh Frydenberg said in a joint statement with other ministers.
It is understood Tony Burke, Labor's environment spokesman, will take a submission to next week's Caucus meeting to recommend that a Labor government would restore the marine park network.
"This is a shocking day for conservation," Mr Burke said after the vote.
"No government anywhere in the world has ever removed an area this large from conservation on land or sea," he said. "The process, which was commenced by Tony Abbott in 2013, has now been completed by Malcolm Turnbull and locked in by the Senate."
Michelle Grady, deputy director of the Pew Charitable Trusts, said "these plans do not go far enough to ensure that nature is protected in the longer term – something that is deeply regrettable to witness".
While Parliament had voted to bring 44 large offshore regions into operation as parks for the first time, bringing necessary protections to a number of important reefs, seamounts, canyons and an array of unique and diverse marine plants and animals, the area of highest protection had been slashed, she said.
"It is incredibly worrying to see that the protective zoning included in the original declaration has been cut by half, leaving much of Australias marine environment vulnerable to industrial fishing and mining," Ms Grady said.
Of the five motions, the reduced protection for the Coral Sea was the most serious because it would allow long-line fishing from the north to the south, and break its sanctuary link to the adjacent Great Barrier Reef, Mr Burke said on Wednesday.
"It's the cradle of the Great Barrier Reef," Mr Burke said. "The government has been at its most brazen", turning the jewel in the conservation crown "into a national embarrassment".