With thousands of government dignitaries, scientists, environmentalists, business leaders and possibly President Obama set to descend on Honolulu in a month for one of the world’s largest conservation conferences, a local fight over whether the Papahanaumokuakea Marine National Monument should be expanded to further protect the marine ecosystem is escalating.

Advocates of the proposal hope that Obama will choose to expand the protected marine area surrounding the Northwestern Hawaiian Islands — quadrupling it in size — in time for the World Conservation Congress, which begins Sept. 1.

Supporters of the expansion include a long list of local lawmakers, including U.S. Sen. Brian Schatz; hundreds of scientists; environmental organizations; and prominent Native Hawaiian leaders, including William Aila, deputy director of the Department of Hawaiian Home Lands; Nainoa Thompson, president of the Polynesian Voyaging Society; and Kamanaopono Crabbe, head of the state Office of Hawaiian Affairs.

But on Tuesday about 70 opponents of the proposal, including advocates for the longline fishing industry, took to the state Capitol in protest, toting signs that read, “Fairness 4 Fishermen,” “Something Smells Fishy,” “Hawaii Fishing Is Sustainable” and “Leave Our Oceans Alone.”

The longline fishing industry would be banned from fishing in the protected area.

Former U.S. Sen. Daniel Akaka and former Hawaii Gov. George Ariyoshi were among a parade of speakers who criticized the expansion, saying that it was being unduly rushed in anticipation of the World Conservation Congress and would harm the fishing industry. They also argued that Hawaii shouldn’t allow the federal government to dictate what happens in local waters, even though the federal government already has jurisdiction over the area in question.

“The ocean belongs to us. We ought to be the ones who decide what kind of use to make of the ocean,” said Ariyoshi. “And we don’t want someone from the outside to come, or people from the outside to come, and tell us how to live with the ocean. They can make those decisions where they live, but don’t come and tell us how we who live here can use the ocean.”

If Obama decides to expand the monument, he’s expected to do so under the Antiquities Act of 1906, which gives him unilateral power to designate U.S. lands and waters as national monuments.

In 2006 former President George W. Bush created the current monument, designating 139,800 square miles as protected. Under the proposal, the area would be expanded to 582,578 square miles.

The area contains more than 7,000 marine species, about a quarter of which scientists believe are endemic. The area is home to large populations of sharks, Hawaiian groupers and other large predatory fish that have been heavily overfished, according to a letter sent to Obama in January from Aila, Crabbe and others asking that the monument be expanded.

Opponents complained Tuesday that Hawaii residents aren’t being given adequate opportunity to weigh in on the proposal.

“It bypasses any decision by the Congress and the state of Hawaii, and this is what this is all about,” said Akaka. “Hawaii needs to know what’s to happen, and there should be transparency.”

The Obama administration has scheduled community meetings for Monday in Waipahu and Tuesday at Kauai Community College in Lihue, but critics say this is inadequate.

Peter Apo, in breaking with fellow trustees of the Office of Hawaiian Affairs, said that the proposal “strikes at the very heart of our sovereignty as a state.”

“In 1893 they overthrew the kingdom and established federal control, and here in 2016 they are doing the same thing with our oceans, except now the victim is the state of Hawaii,” he said.

Apo noted that the size of the expanded monument would be double the size of Texas.

“What is the rush?” he said, echoing the posters surrounding him. “Try wait.”

OHA has voted to support the expansion as long as the office is elevated to a co-trustee position, the cultural significance of the area to Native Hawaiians is recognized and there is no boundary expansion toward the islands of Niihau and Kauai.

OHA said in a statement Tuesday that in the 10 years since the creation of the current monument, no Native Hawaiian who has applied for a permit for the area has been denied access. OHA also noted that the waters designated for expansion have been solely managed by the federal government since 1976.

“Papahanaumokuakea will be the largest marine sanctuary in the world and make us a global leader to show conservation and progress can work hand-in-hand to create a more sustainable future for everyone,” Crabbe, OHA’s CEO, said in a statement.

The proposal has divided members of the overwhelmingly Democratic state Legislature. In April, 28 state lawmakers sent a letter to Obama opposing the expansion; a number of them attended the Tuesday rally, including Reps. Della Au Belatti, Calvin Say, Dee Morikawa, Bert Kobayashi, Lynn DeCoite, Kyle Yamashita and Ryan Yamane.

There is “no scientific justification or conservation benefit” to expanding the monument, the lawmakers wrote in the letter to Obama. “There is only the potential to do harm to Hawaii’s economy, lifestyle, culture and identity.”

The lawmakers said that further restricting waters for fishing would impinge upon the state’s efforts to achieve greater food security.

Hawaii’s longline fishing industry, which uses lines of hooks to catch bigeye tuna, a favorite in Hawaii, as well as marlin, swordfish, mahimahi, moonfish, shark and more, brought in 27 million pounds of fish in 2013 with a dockside value of $85.4 million, according to the lawmakers.

Roughly 8 percent of the catch is brought in from the Northwestern Hawaiian Islands in areas that would be off-limits to fishermen if Obama expands the monument.

The industry includes about 600 fishermen who spend about two weeks at sea at a time, said Sean Martin, president of the Hawaii Longline Association.

He said the association was concerned about the increasing expansion of waters where they can’t fish.

However, supporters of the expansion say that the longline fishing industry wouldn’t be affected much, if at all, by the expansion since longliners are governed by quotas, which they sometimes reach before the year is up. They can fish in other areas, including international waters, to meet these quotas.

Aila said small-boat fishermen would still be allowed in the area and that longline fishing restrictions would help create a more sustainable supply of fish.

The ocean floor would also be off-limits to mineral mining, he noted, which scientists have warned could affect thousands of marine species.

Aila said the argument that the expansion would undermine local food sustainability didn’t make sense given that the fishing industry exports a significant portion of its fish while bringing in foreign imports.

“They import low-quality, junk stuff all the time,” he said.

He said that the World Conservation Congress was an ideal time to expand the monument.

“The possibility of President Obama in the last six months of his presidency having the ability to use the Antiquities Act at a time when the world’s attention is put on Hawaii was certainly a consideration but not the only consideration,” he said. “Other considerations are providing a reserve for tuna, protecting important resources on the bottom of the ocean from ocean mining and protecting the maritime cultural resources of the U.S. and Japan.”