Eavesdropping on Whales
Acoustic buoy could one day help ships avoid collisions
New Yorkers have been surprised to learn that a wide variety of whales are swimming in their watery backyard, cruising New York Harbor sometimes within sight of the Statue of Liberty.
Sounds from humpback, fin, sei, and endangered North Atlantic right whales have been detected in New York waters by an ocean mooring developed at Woods Hole Oceanographic Institution. The instrument relays the signals via satellite in near-real time to scientists and citizens. Signals have come in almost every day since the buoy was deployed in 2016.
WHOI biologist Mark Baumgartner teamed up with New York’s Wildlife Conservation Society to deploy a digital acoustic monitoring instrument, or DMON, about 22 miles off Fire Island near busy shipping lanes entering and leaving New York Harbor.
The DMON sits in a weighted frame at the bottom of the ocean. It is equipped with underwater microphones called hydrophones that listen for whale sounds. “When it hears them, it transmits information about those sounds through a stretchable hose up to a buoy on the surface,” Baumgartner said.
The signals are relayed to Baumgartner’s lab at WHOI and analyzed every day by Julianne Gurnee at the National Oceanic and Atmospheric Administration’s Northeast Fisheries Science Center (NOAA-NEFSC) in Woods Hole. Gurnee reviews the signals in much the same way as a musician reads sheet music, and she can determine what species are present by the structure and patterns of signals.
“With this new technology, we will soon alert ship captains to the presence of the whales and help ships avoid lethal encounters with whales,” Baumgartner said. “We can give near-real-time information to the shipping industry, to suggest to them, ‘Maybe you don’t want to go through this area as fast with your boats as you might like to, because there are endangered whales there.’”
Cargo ships vastly outweigh whales, and ship strikes pose a serious threat to whales. North Atlantic right whales are most at risk. They exist on a razor’s edge with a small population that reproduces at a low rate. Individuals are particularly vulnerable to ships because they swim slowly and are often at the surface. Scientists have said that preventing even two deaths a year could help the species survive.
Baumgartner and WHOI engineers have also deployed DMON-equipped buoys off the Maine and Massachusetts coasts to eavesdrop on whales and learn more about their behavior. Baumgartner has also used DMONs on battery-powered autonomous gliders, which can travel over broad areas searching for and detecting whales. And in 2017, he will test DMONs on wave gliders, which use wave and solar energy to move.
“We can send a glider out to do surveys for us in advance of cruises, ” he said. “So when I go to sea, I know exactly where the animals are.”
Data from DMON buoys and gliders are available at Baumgartner’s Robots4Whales website.