Big Island County water officials reopened Punaluu beach Thursday at noon. A Hawaii County fire helicopter flyover this morning did not show any presence of sharks in nearshore waters. The beach was closed Wednesday morning, after a 29-year-old Captain Cook resident was bitten by a 10-to-12-foot tiger shark while bodyboarding in the area.  He suffered non-life-threatening injuries.  Meanwhile, on Oahu, Ocean Safety officials posted signs Thursday morning at Laniakea Beach on the North Shore of Oahu, warning swimmers of  an "aggressive shark." The 8-foot shark was seen jumping out of the water at about 10:30 a.m.