Swimmers at Popham Beach State Park in Phippsburg were asked to get out of the ocean Wednesday evening after a paddle boarder spotted a great white shark swimming offshore during low tide.

The park, one of Maine’s most popular summer destinations, was closed to all activity around 5:20 p.m. Wednesday, according to an alert issued by the Maine Department of Agriculture, Conservation and Forestry.

“Lifeguards cleared the beach and the purple flag went up,” department spokesman Jim Britt said. The sighting at Popham was confirmed to be a great white, Britt said, but another suspected shark sighting at Reid State Park in Georgetown on Thursday turned out to be a yellowfin tuna. Reid State Park used a drone to identify the fish, Britt said. Purple flags are raised whenever there has been a sighting of a shark in a coastal area.

Popham Beach State Park reopened Thursday at 9 a.m. and no additional shark sightings have been reported, Britt said Thursday evening.

“It has been business as usual today,” Britt said.

State and local officials have logged more than a dozen reports of great white sharks off the Maine coast so far this year. And biologists say there are likely to be more white sharks here in the years to come.

Since early June, the Maine Department of Marine Resources has confirmed at least 14 incidents of white sharks, according to state shark biologist Matt Davis.

“There have been a couple of areas that have had increased activity, in particular Seguin Island and the spot just west of Popham Beach at Hermit Island (in Phippsburg). That area had quite a few white sharks last year, nearly 20 different individuals,” said Davis, who studied great whites in South Africa and Florida.

Public vigilance has increased since a woman was killed by a white shark in Harpswell two years ago, the state’s only fatal shark attack. The town has set up a hotline for people to report shark sightings, logging six reports so far this summer.