In the 1950s, nervous U.S. Navy sonar operators wondered if the mysterious “boing” they heard in their headphones was an enemy submarine. Later, researchers guessed the weird groan was produced by a large fish or marine mammal--noting that it was only heard in winter in a narrow swath of the North Pacific. Now, scientists say they've tracked the baffling boing to its source: a minke whale.
The aural breakthrough came early last month aboard the David Starr Jordan, a U.S. research vessel cruising Hawaiian waters in search of whales and dolphins. Government biologist Shannon Rankin says that hydrophone operators first heard the puzzling sound on 7 November, launching the ship on a several hour chase. Guided by software that allows researchers to home in on noise sources, the crew eventually observed a 7-meter-long North Pacific minke whale surfacing in the vicinity of the boings.
The discovery also revealed a minke breeding ground, says Rankin and biologist Jay Barlow, a colleague at the National Oceanic and Atmospheric Administration's Southwest Fisheries Science Center in La Jolla, California. "They were hiding, all this time, in the rough winter waters of the central North Pacific," says Barlow. Based on the behavior of related whales, the researchers believe the noise is the love call of a male minke.