The Trump administration’s new immigration policies are having an unexpected effect at a quiet but long-disputed border: a lobster-filled waterway between the state of Maine and the Canadian province of New Brunswick.

Known as the gray zone, the region includes Machias Seal Island, home to a large population of puffins and a now-automated lighthouse built by the Canadian government. The U.S. refuses to recognize the structure, though Canada flies lighthouse keepers in by helicopter to keep temporary watch. The island has no permanent residents, but the seabirds draw tourists from both nations—typically a maximum of 30 each day, split between the two countries.

Though the U.S. and Canada have the longest undefended border in the world, this particular