Boston’s NECN is reporting that three Chatham beaches have been closed indefinitely after beachgoers witnessed a white shark (Carcharodon carcharias) preying on a harbor seal (Phoca vitulina) “close to beach.” The three beaches closed are North Beach, North Beach Island and South Beach are closed to swimming. A swimming ban from 5pm to 9:30am still remains in effect for Chatham’s Lighthouse Beach.