In the warm waters of Long Island Sound, a few dozen seals were bobbing up and down Wednesday as U.S. Sen. Chris Murphy toured the shores of Plum Island, the site of an aging animal disease research laboratory slated to close in the next several years.

Overhead, Murphy said, ospreys and hawks soared in search of food across the 840-acre island, which is uninhabited except for the several hundred workers who travel by ferry each day to their jobs studying infectious diseases that were once considered too dangerous to work with on the mainland, such as foot-and-mouth disease.

Near the lab, the island’s deserted beaches serve as a vital breeding habitat for endangered piping plovers and other shorebirds.

“You see things on this island that you don’t see other places in Connecticut or in New York,” Murphy said. “You have a really unique ecosystem on the island because it has been largely uninhabited… It’s just a different ecosystem than exists in other places. It’s worth preserving.”

Murphy — who recalled looking out over the Sound at Plum Island as a kid who spent summers in Old Lyme — stepped foot on the island for the first time on Wednesday, as part of a tour arranged through his leadership of the Appropriations Subcommittee on Homeland Security, which oversees the island’s budget. Later, he spoke about the excursion in an interview.

Earlier this year, Murphy signed a letter along with Sen. Richard Blumenthal and their Senate counterparts in New York, requesting that Interior Secretary Deb Haaland work with President Joe Biden to preserve the “ecological gem” of Plum Island either through a national monuments declaration or other federal conservation effort.

A spokesperson for the Interior Department this week referred a request for comment about the letter to the White House, noting that the president has exclusive authority to set aside federal lands as a national monument. The White House did not respond to a request for comment.

Louise Harrison, the New York Natural Areas Coordinator with Save the Sound, said that momentum has been building this year for the protection of Plum Island as a national monument, which would put it under the same protected status as Devils Tower in Wyoming or Fort McHenry in Baltimore Harbor.

“It doesn’t have to be just for wildlife or just for historical sites,” Harrison said. “National monuments have been created around the country for a variety of purposes”

A letter-writing campaign driven by the Preserve Plum Island Coalition, which is led by Save the Sound, has delivered more than 900 letters in support of a monument designation, Harrison said. On the same day that Murphy toured the island, Blumenthal delivered a letter to Biden calling the island a “national treasure that deeply deserves permanent protection.”

Murphy said that he has not raised the topic of Plum Island directly with President Biden; he noted that the Antiquities Act — signed by President Theodore Roosevelt in 1906 — allows the president to create new monuments at any time.

In addition to the island’s scenic and ecological features, Murphy said that the abandoned remnants of Fort Terry — a World War I era military installation built to protect the entrance to the Sound, and thus, New York City — provided a unique historical attraction that could be the centerpiece of a state or federal park.

“I don’t know whether those buildings are ever necessarily going to be rehabbed to be actively used again, but there’s a future for that island in which there’s a combination of historical and ecological tourism that’s really powerful,” Murphy said. “That’s my pitch to [New York Gov. Kathy Hochul] or President Biden.”

Asked if the State of New York was interested in taking over the island, a spokeswoman for the state’s Department of Environmental Conservation provided a copy of another letter sent to Haaland earlier this year from state officials offering “wholehearted support” for federal protection of the island.

“Plum Island is a historic and ecological treasure with unparalleled natural habitats,” the spokeswoman said in an emailed statement. “New York State remains committed to working with our federal, state, and local partners to help plan a future for the island that protects these critical resources.”

Harrison said that the Preserve Plum Island Coalition has focused its efforts on obtaining federal protection since the mandatory sale of the island to private developers was blocked by Congress in 2020. That left the fate of the island up to the normal process for dealing with excess federal property, which Harrison said gives first dibs to other federal agencies, such as the Department of Interior, followed by other public uses and lastly through public auction.

To help spur interest in a potential partnership between the federal government and local interests, Harrison said the coalition has lined up a private donor willing to “put up millions” toward stewardship of the island.

In the meantime, work continues at the lab with roughly 400 federal employees commuting back and forth each day on ferries from Old Saybrook and Orient Point, New York.

The lab’s eventual replacement, the National Bio and Agro-Defense Facility, is slated to open later this year in Manhattan, Kansas. However, Murphy said it will likely take several more years to fully transition the work from Plum Island to the Great Plains.

“The work that the lab does is so critical both to the country and the world, that they’ve got to be operational right up to the moment that they move to Kansas,” Murphy said. “You can’t have a couple month gap when you’re talking about the world’s preeminent animal disease research lab.”

After meeting with some of the island’s workers on Wednesday, Murphy said they “get a real kick” about the conspiracy theories and rumors of macabre experiments that have swirled around the island for decades. One popular yet debunked myth attributes the origin of Lyme Disease — first identified across the Sound near where Murphy spent his childhood summers — to the government’s work on the island.

While Murphy said that the tall tales surrounding the island are simply fiction, he added that they have worked to keep the island in the public’s imagination after being memorialized in books and movies such as Silence of the Lambs, in which government agents propose using the island as a vacation site for the imprisoned Hannibal Lector.

“It's fascinating history and the sort of legends and mythology around Plum Island certainly contribute to the public’s interest,” Murphy said.

Asked about the condition of the island on Wednesday, Murphy said that the 1950s-era research facility had begun to show its age. That, combined with the cost of transporting everything necessary for the island’s upkeep by boat, had contributed toward the government’s decision to move the facility to Kansas, he said.

While fears about the spread of infectious disease led the Department of Agriculture to choose the island location nearly 70 years ago, the senator said that advances in modern science have eased most of those concerns. Kansas was one of several states that bid to host the new facility, he added.