Sounds of a Humpback (Megaptera novaeangliae)
“It’s sad when any animal dies.” But a mature humpback whale with tissues and organs intact is “an incredible gift to knowledge.”
BU marine biologist
Audio courtesy of NOAA
Darlene Ketten, a marine biologist at Boston University, was making dinner on a Sunday night in early May when she got an email from a friend at the Woods Hole Oceanographic Institution. In the waters off Cape Cod’s northern tip, a humpback whale had been found dead. And not just any whale: a 40-ton female that Provincetown researchers had tracked since she first appeared offshore in 1984. They followed her through adolescence, motherhood-she’d had at least five calves-and maturity. They named her Vector, and the distinctive black-and-white markings on her tail, or fluke, became known to whale enthusiasts from Cape Cod to Canada.
In a city where the thrill of whale watching lures tourists and Bostonians out to sea all summer long, Vector’s death set off an intense race. For dozens of regional researchers, this was a rare opportunity to not only understand the life of a singular humpback, but to explore how we are harming our oceans and the magnificent creatures that live in them. In a matter of 72 hours, Vector’s 80,000 pounds of soaking wet blubber was towed onto a sandy stretch of Cape Cod Bay beach, a team of BU scientists rushed to perform a series of delicate procedures on her carcass right there on the beach, and then the team, with whale tissue samples in tow, hustled back to their lab at BU to begin months, perhaps even years, of studies.
All in the interest of science.
It was a fisherman who first spotted the enormous body floating in the ocean nine miles northeast of Race Point Beach on Saturday, May 4. Provincetown’s Center for Coastal Studies dispatched a boat and identified her as Vector. By late Sunday, the tide was carrying her south, onto a narrow strip of beach in East Sandwich. Most humpbacks sink to the bottom of the sea after they die, becoming food for sharks or decomposing too quickly for researchers to learn anything much of value. “It’s sad when any animal dies,” says Ketten, a BU College of Engineering senior research scientist. But a mature humpback carcass with tissues and organs intact is, she says, “an incredible gift to knowledge.”
Humpbacks typically live a half-century or even much longer. Vector died at about 37. Ketten, her team at Boston University’s Hearing Research Center, and other scientists, had so many questions they wanted to explore: Why did she perish so young? Was she ingesting human-generated debris or chemicals that might have harmed her? What sort of sounds was she hearing? And what could her death teach them about what humans are doing to our seas and how that activity affects whales?
Answers to these questions, among others, have eluded scientists, simply because 40-ton, seemingly healthy humpback whale carcasses with very little decomposition don’t wash up on our shores very often. So when Vector did, every second counted.
Whales have ears?
They need Vector’s ears.
Humpbacks are baleen whales, a species that has bristly plates instead of teeth, which they use to capture krill, zooplankton, and other small fish. Among the biggest whales, humpbacks patrol all seven oceans, migrating thousands of miles each year. A mainstay of New England’s tourism economy, humpbacks, which migrate between the Caribbean and North Atlantic oceans, delight whale watchers from Maine to Provincetown with their acrobatic jumps and dives. The males among these gentle giants fill the ocean with song-howls, cries, barks, and melodies scientists are working to decipher. They likely use their songs to communicate, navigate, mark territory, and find mates and food. Humpbacks create the most complex songs of all whales, says Ketten. They weigh an average of 40 tons, making Vector pretty typical. Scientists liken their length to a school bus. They have long, wing-like white flippers and powerful flukes, with markings as unique as fingerprints, enabling researchers to track humpbacks through photo identification. But none of these imposing features are as crucial to a whale’s survival skills as the organs that lie under thick layers of blubber, muscle, and bone attached directly to their skull: the ears.
Whales have evolved over millions of years to be able to hear extremely well underwater, using their ears to navigate the vast ocean waters just as humans use their eyes to navigate their homes, streets, and sidewalks. It’s how they get around. One reason that whales hear so well is that they have three to five times more brain cells dedicated to hearing than humans do. Ketten is investigating other possible reasons, as well as figuring out what exactly whales can hear.
Humpbacks, like other whales, are protected under the Endangered Species Act (1970) and the Marine Mammal Protection Act (1973). But unlike North Atlantic right whales, which are critically endangered, the humpback population has been steadily increasing since commercial whaling was banned in 1985. Still, dangers from humans persist: vessel strikes, climate change, plastic debris, and commercial fishing gear, ropes, nets, and traps that entangle whales, wrapping around their tails and necks, constricting their ability to breathe and swim. An unusually high number of humpbacks have died since January 2016 along the Atlantic coast, from Maine through Florida, according to the National Oceanic and Atmospheric Administration (NOAA); although the cause of death has not been determined in most cases, some of the carcasses showed signs of vessel strikes.
And then there is noise. The oceans are naturally noisy places; think of waves, volcanic eruptions, storms, and sounds created by marine creatures. But now there is growing concern about underwater noise pollution-from shipping traffic, construction, seismic air guns used in oil and gas exploration, sonars, and military training-all of it occurring in parts of the sea that are habitats for humpbacks. Little is known about how this human cacophony is impacting these whales. Ketten says the major concern is twofold: Will humpbacks be disturbed by noise pollution that could disrupt their feeding, mating, and other critical behaviors? And will they be exposed to frequent, extremely loud sounds that impair their hearing?
“How much sound are we putting into the oceans, and what is it bothering?” says Ketten, whose authoritative and unflappable charm brings to mind the actress Frances McDormand. “It’s a huge question, because we realize that in some places, like the North Atlantic, we’re creating, essentially, the equivalent of an industrial plant.”
As scientists learn more about how noise pollution is impacting whales like Vector, they can create protections for species like the humpback, for example, by devising alert systems to warn whales away from harm without, as Ketten says, “spooking them.”
In 2000, Ketten helped lead an investigation of the mass strandings, and deaths, of whales in the Bahamas, following the Navy’s use of sonar during training exercises there. Scientists concluded that the exercises disturbed one group in particular-beaked whales. “The nervous Nellies of the sea,” Ketten calls them. “When sonar goes off, they freak and try to run away from it. On the other hand, pilot whales really like sonar-they come up to the ships and they mimic it. So every species is different.”
That mass stranding in the Bahamas helped focus attention on ocean noise pollution and whales.
If Ketten and her team could get their hands on Vector’s ears, and if those ears were in fairly good condition, it could help them learn more about how and what humpbacks hear, and at which frequencies and intensities human-caused sounds become disruptive to their behavior. With that information, researchers could understand which man-made sounds pose the most risk to whales, causing them to swim into areas where they are at greater risk of being harmed or of beaching.
But when it comes to conducting research on whales, there are two significant obstacles for scientists: Finding them. And holding them.
“Their natural environments are huge and three-dimensional,” says Tyler Perrachione, a Sargent College of Health & Rehabilitation Sciences assistant professor of speech, language, and hearing sciences, and associate director of BU’s Hearing Research Center. “And you can’t keep them in a lab like mice or birds or monkeys.”
Then there is what Ketten worries about. Money. Funding for research on whales and marine mammal hearing is tough to come by; the BU team’s latest grant of approximately $500,000 over two years, from the Joint Industry Program, will expire soon. Working out of a cramped lab in a decades-old building on Cummington Mall, where sensitive auditory experiments compete with vibrations from the Massachusetts Turnpike and the clatter from the MBTA’s Green Line, the team can hardly afford to waste time or money on travel and research that might well yield no usable results.