High rents are choking the food sellers in the booming Seaport say restaurateurs who are leaving or afraid they’ll be forced out of a saturated market they say is making business bad for everyone.

Salvatore’s, a fixture for more than a decade on Northern Avenue near D Street, closed at the end of April and owners of J. Pace and Son, a neighboring longtime tenant, are worried they may have to leave as well.

La Casa de Pedro at Congress and D streets recently filed for bankruptcy after running up millions in debt over the 18 months it’s been in operation, and co-owners Luis Maggioli and Pedro Alarcon are struggling to stay afloat.

“The rents here are outrageous for what the Seaport has to offer. The only thing it has to offer are restaurants,” said Maggioli. “We got into this space thinking it was a gold mine, that it’d generate hundreds of thousands of dollars a week, but that’s not true.”

The Seaport has seen skyrocketing rents as development increases, with La Casa de Pedro paying more than $50,000 a month — $600,000 a year — for its space, according to lease documents.

In contrast, Salvatore’s original lease, which began in 2006, had a monthly lease of $10,125 a month, or $121,500 a year, according to documents filed with the city’s licensing board.

“It is increasing. It’s reasonable to assume that some restaurants will not be able to handle it,” said Brendan Carroll, director of intelligence at Perry Brokerage. “Rental values in the Seaport are such a moving target. Landlords are very optimistic about the prospects for ground-floor retail spaces.”

Salvatore’s owner Peter Ackerman said he was looking to remodel the restaurant to reflect the changes in the Seaport, but he said he couldn’t secure financing before his building’s property manager was going to escalate his rent in a new lease. But just as concerning was the drain of customers as new restaurants opened up, Ackerman said.

“It’s exciting, but I see more and more restaurants, more competition for everyone down there. You start to get concerned,” Ackerman said. “Everybody wants to try new places. Each time a new place opened that many more people aren’t coming to our restaurant. We’re a couple years away from all the humans getting down here that we’re waiting for.”

“It seems like every building wants a restaurant in the base. There’s a saturation point at some point; there’s only so many restaurants (the Seaport) can hold,” said George Lewis, owner of Pastoral in Fort Point.

J. Pace and Son shares a landlord with Salvatore’s, and general manager Joseph Pace III said Salvatore’s closing was a “red flag.” Pace’s lease expires in May 2019 and while he did not say what he’s currently paying, he said based on Salvatore’s rent he was expecting the company to double or triple his current rent.

“We’re going to do everything we can to negotiate our best lease to stay there because we love it in the Seaport — the people are fantastic,” Pace said. “But unfortunately if it gets to the point where we’re not able to sustain our rent month to month, it’ll be really sad. We’ll have to close the location.”

The property management company could not be reached for comment.

Alarcon, the Casa de Pedro co-owner, said he recently discouraged another restaurant operator from coming to the Seaport, and said though rents are likely to be even higher in the future, it would be wiser to wait until more diners are in the area.

“If I had to rewind the past I’d be happy to wait until things were completed. It’d cost more money but I’d lose less money,” Alarcon said.