PORTLAND — The Portland Science Center has closed after three years of bringing traveling exhibits about pirates, sharks and the human body to the city’s waterfront.

The Massachusetts-based owner of the center, The Gold Group, has closed the business and will opt out of its lease, said Stephen Goodrich, owner of the building at 68 Commercial St., where the center was housed.

Goodrich said Tuesday he didn’t know all the specifics, but was told that the science center’s attendance had declined recently, compared to its early exhibitions.

“I had a conversation with Joe Gold (the owner) a couple weeks ago and he was happy with the facility and the support we’ve given him, but he wasn’t getting quite the same response in terms of visitors,” Goodrich said.

Goodrich said his lease with the science center included an opt-out clause, in case the business wasn’t successful, and he will honor that clause.

Gold, the agency principal at The Gold Group, did not respond to phone messages left at his office or to emails seeking comment Tuesday evening.

A visit to the Science Center on Tuesday afternoon revealed that the most recent exhibit – about sharks – was on its way out the door.

Several workers were packing crates and boxes with displays from the “Planet Shark, Predator or Prey” exhibit into trucks. They said the exhibit, which opened in February, would be moved to an out-of-state location.

The science center’s website does not list any current or upcoming exhibits. Its Facebook page says the shark exhibit ended Sunday and thanks people for visiting, but provides no additional information.

The Portland Science Center opened in September 2015 with the show “Body Worlds,” featuring preserved human bodies. The center, a for-profit business, had hosted about two exhibits a year, including a popular one on the wreck of the Titanic.

The Gold Group, which is based in Salem, Massachusetts, promotes and produces educational exhibits around the country. Exhibits promoted by the group in other cities include “Dead Sea Scrolls,” “Sea Monsters Revealed” and “Pompeii.”

Dinah Routhier, 9, reacts after placing her hand on a sample “glacier” at “Titanic: The Artifact Exhibition” at the Portland Science Center. (Jill Brady/Portland Press Herald file photo)