Environmentalists and fishing groups said Thursday they are prepared for a legal battle in the wake of Interior Secretary Ryan Zinke’s decision to preserve the nation’s first Atlantic Ocean marine monument.

President Barack Obama designated Northeast Canyons and Seamounts Marine National Monument a little less than a year ago. It’s 5,000 square miles of underwater canyons and mountains off New England’s coast.

President Trump assigned Zinke to review more than 20 monuments, including Northeast Canyons. Zinke recommended Thursday that all the monuments remain but said some of them could be altered.

The Atlantic monument has been contested from the beginning. Some fishing groups have said it was created through an illegal use of the Antiquities Act of 1906 and jeopardizes their industry, and they’ve sued to challenge its creation.

“I’m sure fishermen will appreciate any relief they get from the administration, but unless the monument is revoked it won’t cure the legal problem that we highlight in the lawsuit,” said Jonathan Wood, an attorney with the Pacific Legal Foundation, which is representing the fishing groups.

But conservationists said the monument protects marine mammals, sea turtles and underwater habitats. They celebrated Thursday’s news but agreed that the case is almost certainly in for a long court battle.

The monument’s designated area is at the edge of Georges Bank, a critical fishing area east of Cape Cod and south of Nova Scotia. Fishermen on Georges Bank harvest species such as haddock and lobster that make up the lifeblood of the New England fishing industry.

The monument area also contains fragile deep sea corals and vulnerable species of marine life, said Peter Auster, a senior research scientist with Mystic Aquarium in Mystic, Connecticut.

“Having a place where animals can interact in absence of human disturbances is important,” Auster said. “It’s important for the rest of the nation and indeed the world to know there is somewhere like this that is untrammeled by humans and will remain in perpetuity.”

Zinke has not yet provided specifics about which monuments could be changed or exactly how. He said in a statement that his recommendations about the monuments will “provide a much needed change for the local communities who border and rely on these lands for hunting and fishing.”

The federal Department of Commerce is also reviewing the marine monument’s status. A spokeswoman said a public comment period on that review ended Aug. 15 and no decisions have been made yet.

The Northeast Canyons monument was the first of its kind created in the Atlantic. It’s also the first off the contiguous U.S, though the federal government manages four marine national monuments in the Pacific Ocean.

They are relatively new creations, as the first was established under President George W. Bush. All of them were subject to Zinke’s review.

The fishing groups suing to try to overturn the creation of the Atlantic monument include the Massachusetts Lobstermen’s Association, Atlantic Offshore Lobstermen’s Association, Long Island Commercial Fishing Association, Rhode Island Fishermen’s Alliance and Garden State Seafood Association. Members of the groups said Thursday they are optimistic their fishing rights will be restored.

The area should be open to fishermen because of Americans’ demand for local seafood, said Richard Fuka, president of the Rhode Island Fishermen’s Alliance. He said his members need the area to harvest squid, which is one of his state’s signature seafood items.

“Losing that ground was not only a financial impact, but it also harms people in not being able to have a locally caught consumable product,” he said.