MEXICO CITY — Scientists working off Mexico's Yucatan Peninsula began using sound waves to search for information about an asteroid that may have wiped out the dinosaurs 65 million years ago.

The research project began despite concerns among environmental activists who say the technology could harm whales, sea turtles and several varieties of fish in the Gulf of Mexico.

Mexican authorities say the project is within acceptable limits and will be closely monitored.

Sergio Chan Lugo, the Yucatan state representative for Mexico's environmental protection agency, told local media the sound blasts began early Friday.

The project includes marine seismologists from the University of Texas Institute of Geophysics, the Geophysics Institute at Mexico's Autonomous National University and Cambridge and London universities.

They are using the underwater seismic pulses to learn more about the Chicxulub Crater, a depression measuring about 120 miles in diameter and centered just outside the port of Progreso, 190 miles west of Cancun.

But environmentalists say the sonic blasts damage the brain and ears of marine mammals and other species and disorient the animals so that they beach themselves or crash into boats.

Scientists acknowledge there's evidence that points to Navy sonar causing whales to beach themselves. But they say there's no proof that seismic pulses have harmed marine animals, though more research is needed to draw firm conclusions.

The Maurice Ewing, the research vessel from which the scientists are working, is owned by the U.S. National Science Foundation.