In the first two weeks of August, there have been dozens of beach closures on Cape Cod and the Islands because of shark sightings.
There have been at least 38 closures as of Wednesday, mostly in towns north of Chatham on the Outer Cape, up to Provincetown, according to a Globe tally.
The beaches with the most sightings in August so far are Nauset Beach in Orleans with 12 closures, and Head of the Meadow Beach in Truro with 10 closures.
The drumbeat of shark-related closures continued Wednesday with Newcomb Hollow Beach in Wellfleet and Nauset Beach closed because of shark sightings, officials said.
Newcomb Hollow Beach was closed to swimming from 9:15 a.m. to 10:15 a.m. because of a shark sighting, Wellfleet Beach administrator Suzanne Thomas said.
Nauset Beach closed to swimming for one hour starting at 11:30 a.m., a Nauset Beach employee said.
It was the second day in a row that those beaches have closed because of shark sightings.
Concern over swimmers’ safety because of sharks has been heightened after 26-year-old Arthur Medici was killed in a shark attack at Newcomb Hollow Beach last September. It was the first fatality from a shark in Massachusetts in 80 years.
This summer, an annual charity swimming event in Provincetown Harbor was forced to change its route after Cape Cod National Seashore officials denied it a permit because of the number of great white sharks.
“The appearance of white sharks due to the increased seal population has created concern for swimmer safety in the deep waters off Long Point,” officials said in a statement.
The Globe has been maintaining a list of shark-related beach closures by reviewing official online posts from the towns and the Atlantic White Shark Conservancy, checking media reports, and contacting town officials.
Ryan Wright, acting chief ranger of the Cape Cod National Seashore, said Wednesday that people can protect themselves while swimming by following shark-smart practices.
“You want to be aware as a swimmer that sharks are going to be hunting for seals in shallow waters,” he said.
Wright advised that swimmers should stay in shallow water, limit splashing, and only surf, kayak, or conduct related activities in groups. He also said that beachgoers along the Cape should avoid seals, visible schools of fish, or murky water, and follow posted signage and lifeguards’ instructions.