A whale of a sound system

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Small survey planes, daylight and luck have long been the best tools for scientists hoping to spot the rare North Atlantic right whale. The results aren’t too impressive.

An estimated one in four whales are spotted by aerial surveys, leaving the rest vulnerable to ship strikes or fishing gear entanglements.

But scientists say an underwater listening system they’re developing will dramatically improve detection and reduce whale deaths.

The “passive acoustic” system would find whales and immediately transmit their location to nearby vessels.

“It will reduce (ship) strikes, period,” said Richard Merrick, chief of the protected species branch at NOAA Fisheries, New England.

Only about 350 North Atlantic right whales remain. In the last 14 months, at least eight have been found dead, though scientists recently speculated there could be far more deaths that were never discovered. Four of the known deaths were attributed to ship strikes and one to fishing gear entanglement.

The underwater microphones could allow scientists to pinpoint up to 75 percent of whales in areas they’re known to frequent and reduce collisions, Merrick said.

It would enable scientists to scan for whales all the time, instead of just in sunlight or good weather. Researchers wouldn’t be as dependent on the sometimes dangerous aerial surveys, or the luck needed to be overhead when a whale surfaces.

Scott Kraus, vice president of research at the New England Aquarium, said the listening system seems to work “terrifically,” but cautioned it won’t solve all the whale’s problems. The North Atlantic right whale is quiet compared to crooners like the humpback. It sings to communicate, not as a way to find food, so the noises are less frequent, he said.

In addition, different ages and sexes of the whales may make noise at different times, making the system less effective at spotting them. For instance, Kraus said new mothers and calves may keep quiet to avoid detection by predators.

The system is at least three years from being fully in place in areas the whales frequent off New England, such as Cape Cod Bay.

Complicated negotiations with shipping and fishing interests are needed to ensure vessels will use the new information to change their routes or slow down to avoid the whale.

“Just knowing their whereabouts isn’t a conservation act in itself,” said Dave Wiley, research director at Stellwagen National Marine Sanctuary off Massachusetts, where several underwater microphones will be deployed over the next year.

William Eldridge of the Boston-based shipping company Peabody & Lane said mariners want to avoid collisions and would be willing to work with a new system that could precisely locate the whales. The problem now is that ships are being asked to take action based on little more than a good guess.

“A system that tells you there are whales on your heading, that’s a good thing,” he said.

“Otherwise it