In the deep, cold waters off Massachusetts, the world's last 350 or so North Atlantic right whales search for each other with soft, drawn-out "whoops" and "moos." The ethereal sounds travel for miles in the dark undersea to help the leviathans meet to mate and share feeding grounds.
Now, scientists are using those calls to help the whales survive.
They have developed a cutting-edge underwater listening system to protect the creatures from their number one killer: ships. The Massachusetts Bay network can track right whales by their signature call - and in as little as 20 minutes warn mariners to slow if they're too close.
The devices are also giving scientists unprecedented insight into how the creatures change behavior to respond to the cacophony of man-made noises in the bay.
"We need to listen to these whales" to save them, said Christopher W. Clark, director of Cornell University's Bioacoustics Research Program, which developed the technology with Woods Hole Oceanographic Institution.
Clarks said an increasing number of pipelines, cruise ships, tankers, and construction projects are drowning out the whales' soft calls, making it difficult for them to connect. Clark has evidence that the whales simply don't "whoop" when the bay gets too noisy.
"In the world of right whales, we know it's a noisy place to live," Clark said in an e-mail. "Underwater [is] not much different than living on the tarmac at Logan."
Today, Clark's lab is launching listenforwhales.org to allow the public to see where whales are being detected in the busy shipping lanes that run through the bay's Stellwagen Bank National Marine Sanctuary. Visitors to the website will also be able to listen to whale calls and learn more about the creatures.
The listening system, which is estimated to cost $47 million over the 25- to 40-year life of the project, is initially being paid for by Excelerate Energy, which recently finished construction of New England's first offshore liquefied natural gas port, 13 miles southeast of Gloucester. If a second proposed port is built nearby, it will share the costs of the network. Federal officials demanded the monitoring system because vessels delivering gas will steam through the whale-laden sanctuary.
Ten yellow buoys are now spaced 5 miles apart in a 55-mile stretch of the shipping lanes around Cape Cod, heading into Boston. Each buoy is equipped with an underwater hydrophone that can detect right whales within 5 miles. If a buoy detects a whale, the natural gas ships are required to slow from 12 to 10 nautical miles per hour over the next 24 hours near that buoy - and position someone on board to search for whales by sight. While the speed change is small, research shows that a lookout, combined with slower speed, significantly reduces whale strikes and deaths.
Researchers sadly joke that there are so few North Atlantic right whales left in the world they can identify each one personally by naturally roughened skin patches on the tops of their heads. Those small numbers mean that even one death of a breeding female could contribute to the species' extinction.
The dark-colored whales - so-named because they were the "right" whale to kill for oil because they floated when dead - have never made a comeback after being hunted nearly to extinction in the 1700s. Many of the creatures get tangled in fishing gear, but scientists say ships are their major killer: At least one-third of all the right whales that died in the last decade died from ship strikes.
The creatures feed on zooplankton near the sea surface, often right in the path of ships entering or leaving Boston. Ship captains often don't know they have hit whales until they find them wrapped around the bow in port.
"If a ship over 65 feet in length going 12 nautical miles an hour hits a whale, data shows that whale is most likely going to die," said Leila Hatch, regional marine bioacoustic coordinator for the Stellwagen sanctuary, which came up with the concept of the listening system. "We need to do our best to make sure ships are in different places than whales."
Until now, researchers tracked right whales on boats or in airplanes. But the search was often thwarted by bad weather, darkness, and an expansive sea where even a 50-ton whale can be hard to spot.
Scientists have long been working on a better way of locating the creatures by their distinctive call. Clark, of Cornell, knew that right whales made audible upcalls - that soft "whoop" - that could be isolated from the background hum of the ocean. But the buoy team had to overcome technological problems to design a system that could hear the whale, verify the sound, and then quickly tell mariners.
One of the trickiest challenges: figuring out a way to hear the whale over the din of the buoy system that holds the hydrophone, an underwater listening device.
"It's like when you put a microphone out of your car window going 5 miles per hour, it's the same thing in the water column - it picks up all the noise as the buoy goes up and down in the water," said John Kemp, the Woods Hole engineer who, with his colleagues, spent four years designing a solution. The team ultimately came up with a "gumby hose" that allows the hydrophone to remain stationary and not pick up sea noise.
Clark says the devices are already showing that the whales are in the shipping lanes far more often than researchers had thought. And New England Aquarium right whale researcher Scott Kraus says the devices will help him and other scientists better understand whale movements at night and in bad weather - and help build the case that all ships should be required to slow down when whales are nearby.
"At the end of the day, we want these devices to help ships and whales co-exist," said Dave Wiley, the sanctuary's research coordinator.
Beth Daley can be reached at firstname.lastname@example.org.