SAN JUAN, Puerto Rico – U.S. Navy sonar tests likely caused 16 whales to beach themselves in the Bahamas last year, according to a federal study released Thursday.

The whales swam on shore on the islands of Abaco, Grand Bahamas and North Eleuthera on March 15 and 16 as Navy ships were testing sonar in the area. Six whales died, including five Cuvier beaked whales and a Blainville’s beaked whale. The others were pushed back into the sea.

Earlier, the Navy had questioned a link between its sonar tests and whale beachings.

But the joint study by the Navy and U.S. National Marine Fisheries Service was based on examinations of the corpses of five of the six dead whales.

Each of the whales had hemorrhaged near its ears, said the 66-page report.

It said the wounds would not be fatal but could have led the animals to become disoriented and swim on shore.