An underwater expedition near the Isla del Coco has tagged 15 hammerhead sharks, according to the  Programa Restauración de Tortugas Marinas.

Some 16 divers from the United States and the United Kindom worked from July 3 to July 15 putting transmitters on the underwater predators.

Five fish were given tranmitters that can be tracked via satellite, said the organization. Some 10 more were fitted with acoustical trasnmitters that could be tracked in the area around the island.

This was the fourth of seven planned expeditions. The sharks fitted with satellite transmitters will be tracked to learn about migration routes, the group said. Some of the transmitters will operate for four months. Others will work for less time.

All the sharks fitted with transmitters were adult females encountered some 70 feet or so below the surface, the organization said.

The project was done in conjunction with the U.S. Shark Research Institute and the local diving firm  Undersea Hunter.

The Isla del Coco is a national park with extensive amounts of sea creatures about 330 miiles west of the mainland.