CHATHAM (CBS) – A handful of beaches in Chatham have been closed to swimming indefinitely after marine biologists tagged a 20-foot great white leaving Chatham Harbor.

Officials say they made their decision after that shark sighting, along with two buoy readings that indicated other tagged sharks had entered the harbor on August 30 and September 9.

As a result, Lighthouse Beach and all east facing ocean beaches remain closed from the Orleans/Chatham line south along Nauset Beach to Monomoy until further notice.

Cape beaches have been shut down several times over great white shark concerns this summer.