The Right Whale Listening Network developed by the Cornell Lab of Ornithology and Woods Hole Oceanographic Institution recognizes the whales' distinctive calls and routes the information to a public Web site and a marine warning system, giving ships the chance to avoid deadly collisions.

Right whales were hunted to the brink of extinction centuries ago, and now fewer than 400 of the 50-ton, long-lived black whales remain, scientists said, noting collisions with ships are currently a leading risk factor.

"For the first time, we can go online and hear … calling whales, and see where those whales are in the ocean off Boston and Cape Cod," said Christopher Clark, of the Lab of Ornithology. "Better yet, those calls immediately get put to use in the form of timely warnings to ship captains."

Clark said even the deaths of one or two breeding females each year could lead to the population's extinction.

"If all ships slow down for whales, it could make a real difference," he said.

The sounds and additional information are available at http://listenforwhales.org