President Trump speaks at a roundtable discussion with commercial fishermen at Bangor International Airport on Friday. He said, “We are reopening the Northeast Canyon and Seamounts Marine National Monument to commercial fishing. Is that OK? is that what you want? That’s an easy one.” Patrick Semansky/Associated Press

WELLS — President Trump used the occasion of a visit to Maine last week to do right by an industry that hasn’t had much good news lately when he reopened to commercial fishing nearly 5,000 square miles of ocean south of New England that President Barack Obama closed in 2016.

Stay tuned. In the process of righting a wrong, Trump’s action, announced at a Bangor roundtable, has once again set hair on fire in the environmental community, tested the limits of presidential power and set the stage for litigation.

Obama created the area, known as the Northeast Canyons and Seamounts Marine National Monument, just a few months before he left office. He portrayed the monument, the only one in the Atlantic, as a hedge against climate change.

Spanning four canyons and three seamounts, the monument is home to cold-water corals, endangered whales and turtles and numerous fish species.

If Trump’s action was controversial, it should be seen as no less so than the process that created the monument. Fishing in U.S. territorial waters is managed by the National Marine Fisheries Service, which is charged with providing productive and sustainable fisheries based on the best available science. NMFS works with regional councils to ensure all stakeholders are heard and that its regulations have “ground truth.”

The monument process, on the other hand, relies on the 1906 Antiquities Act, which was originally conceived as a means of allowing President Theodore Roosevelt to preserve Native American ruins and artifacts – a noble calling, to be sure, but not one that leaps to mind with respect to the wise use of marine resources.

Nevertheless, use of the act has expanded over the years and it is routinely invoked by presidents looking to burnish their environmental legacy on their way out the White House door. So much so, in fact, that The New York Times, in 2015, wrote, “There are at least two more monuments we would recommend to Mr. Obama before he retires.”

Seamounts is south of Cape Cod and not routinely fished by Maine vessels. But the principles at stake were not lost on the fishermen, mostly Mainers, who participated in a Bangor roundtable with the president Friday. Frank O’Hara Jr., whose boats fish off Alaska as well as New England, said, “It will affect us because once they take one mountain, one canyon, they’ll take another one, and another one …”

Obama also considered the area around Cashes Ledge, 80 miles off Rockland, for monument status, which would have been devastating for Maine fishermen. Ultimately, he took a pass, but environmentalists have not given up on the idea.

The green reaction to Trump’s proclamation has been strident, to say the least.

EarthJustice accused the president of “shredding” protections for the monument, even though Trump merely reopened the area to commercial fishing. The monument already was open to recreational fishing, and it remains closed to mining and oil exploration. The coral formations at issue are as deep as 4,000 meters and never have been even remotely at risk of harm from fishing.

The Natural Resources Defense Council and the Conservation Law Foundation say they are prepared to sue the administration.

Legal challenges to the reopening seem certain to focus on whether a president has the authority to reopen a monument. Yet the issue of how marine protected areas are derived is critical to the discussion.

Cutler’s Kristan Porter, president of the Maine Lobstermen’s Association, characterized the Seamounts national monument designation as a “backroom deal” that excluded fishermen.

“We think our expertise and our knowledge should count for something,” he rightly argued.

Research often shows that the net result of a marine protected area has been to shift fishing from inside the area to outside, with no effect on regional abundance. In such cases the fishermen’s costs tend to rise, or the allocation – who gets the fish – shifts, fairly or not. In either case, there is no benefit to the resource.

That Trump is something of a lightning rod should not bear on his Seamounts proclamation. As Bob Vanasse, executive director of the industry group Saving Seafood, told The Boston Globe, “Whatever anyone thinks about President Trump is irrelevant.”