The Australian government announced Thursday that it is creating the world’s largest network of marine reserves, a patchwork of protected areas covering more than 1.1 million square miles of ocean.

The move, which comes on the heels of California’s vote last week to create the largest marine reserve network in the United States, signals a growing movement to put some of the sea’s most ecologically valuable areas off-limits before they are damaged beyond repair. But they also reflect the political and economic pressures elected leaders face as they balance conservation with activities such as fishing and oil drilling.

The Australian plan, for example, angered commercial fishing interests while disappointing some environmentalists by falling short of the protections they envisioned. In California, the just-finalized network of state underwater parks drew complaints from a Native American tribe that said the new restrictions could infringe on its long-held harvesting rights.

Australia timed its announcement to coincide with the run-up to the Rio+20 Earth Summit, a global gathering next week where leaders from more than 130 nations will meet to discuss how to ensure economic development while protecting key parts of the environment.

“We have an incredible opportunity to turn the tide on protection of the oceans and Australia can lead the world in marine protection,” Environment Minister Tony Burke said Thursday, according to the Associated Press.

Jessica Meeuwig, a University of Western Australia professor, said: “Marine reserves, including fully protected sanctuary zones, are an essential contribution to ensuring healthy oceans.”

“The science is clear on this,” she added in an e-mail. “Compared to areas open to extraction, marine sanctuaries have significantly more species, higher numbers of individuals and significantly larger animals.”

The drive to create marine reserves — some of which are fully protected from exploitation, others which allow for activities including fishing and mining — is taking place on two fronts. It targets several of the most remote, biologically rich spots in the ocean, such as Australia’s Coral Sea, along with some near-shore areas where local communities are willing to restrict their activities.

“If we’re going to protect 10 percent of the ocean by 2020, the first places that need to be protected are the last wild places in the sea,” said Enric Sala, a National Geographic explorer in residence. “But we still need to create hundreds of thousands of protected marine reserves in places where people live and fish to make a living.”

The centerpiece of Australia’s announcement is a no-take reserve of 193,000 square miles in the Coral Sea, roughly the size of Spain, which will rank as the world’s second-largest fully protected marine reserve. Situated east of Australia’s Great Barrier Reef, the region boasts vibrant reefs and deep-water sharks, as well as tuna and marlin.

Joshua Reichert, managing director of the Pew Environment Group, whose organization has lobbied for a no-take reserve in the Coral Sea and in other regions, said these remote areas need to be protected before they become accessible and depleted.

“Many of the large places in the world’s oceans that are still intact and have been minimally impacted by human activity are not going to stay that way forever,” he said. “We have a window of opportunity to protect these places while we still can. Twenty years from now, many will be a shadow of what they are today.”

In addition to more tropical waters, the new plan — which was more than a decade in the making — would protect areas in cold-temperate waters off southern Australia, where blue whales, whale sharks and Australian sea lions live. But the government will keep regions in northwestern Australia and in the Great Australian Bight accessible for oil and gas drilling.

These compromises did not satisfy Australia’s commercial fishing industry, whose officials described the new safeguards as a “rush to Rio,” where the government was overly invested in making a splash for its conservation efforts.

“Tens of thousands of families in Australia’s regional communities will be damaged by the government’s proposals,” Brian Jeffriess, a spokesman for the Commonwealth Fisheries Association, said by e-mail. “This is a kick in the guts for these forgotten communities who have been sacrificed so that the government can tell the world that Australia has the biggest parks of all.”

In California, the new marine network has generated less controversy because an array of interest groups met to craft each section of the plan. The chain of more than 100 protected areas puts 8 percent of the state’s waters off-limits to any extraction, while imposing restrictions on an additional 7 to 12 percent of coastal waters.

“In 20 years working on these issues, I’ve never seen such a public process,” said Michael Sutton, vice president of the California Fish and Game Commission. “Everyone who had a stake had a say.”

On a flight two years ago over Point Sur, Sutton pointed from the cockpit of his Cessna to the dense cover of kelp forest below, which received full protection under California’s plan. “These are the redwoods of the underwater world,” he said.

Not everyone endorsed the final plan: Just before the commission’s unanimous approval of the Northern California portion of the network last Wednesday, Yurok Tribal Chairman Thomas P. O’Rourke Sr. issued a statement saying, “The proposed project simply does not do enough to address tribal rights.”

But several other area tribes did endorse it, and Native American tribes elsewhere are leading the drive to protect marine areas. Pat Pletnikoff, who serves as mayor of St. George Island in Alaska’s Bering Sea, journeyed to Washington this week to lobby for the creation of a national marine protected area that would cover 60 miles around the island.

The proposal would bar trawl equipment that is damaging two massive underwater canyons there but still allow local Aleuts to fish there. Pletnikoff, who also serves as chairman of the St. George Fishermen’s Association, said he told the National Oceanic and Atmospheric Administration’s Fisheries Service director, Eric Schwaab, on Wednesday that the federal government needs to act to protect the area’s fur seals and marine birds, as well as the tribe’s subsistence rights.

“We want to protect the whole ecosystem,” he said in a phone interview. “It’s suffering terribly, and something needs to be done.”

Project AWARE is a member of Protect Our Coral Sea and Save Our Marine Life - two alliances of nonprofits environmental organisations working hard on the marine reserve agenda in Australia.