The U.S. Navy has launched an investigation to determine if there is any connection between a mass beaching of dolphins in the southeastern state of Florida and nearby naval maneuvers involving a sonar-equipped submarine.

Investigators said Saturday that the USS Philadelphia was conducting exercises with Navy SEALS (special teams) 65 kilometers from the Florida coast where as many as 70 dolphins inexplicably beached themselves on Wednesday. At least 20 rough-toothed dolphins died.

Scientists believe that loud bursts of sonar, heard for miles under the sea, can disorient or scare marine mammals. In March 2000, four different species of whales beached themselves in the Bahamas after a U.S. naval battle group used active sonar in the area.

Experts are conducting necropsies on the dolphins looking for trauma signs that may have been caused by loud noises.