Modern drone technology is helping to find and protect one of the world’s most endangered marine mammals.
Eighty kilometres south of Bar Harbor, Maine, on a raw day in December 2012, the research vessel Endeavor was surfing a storm through whale country. Thirty-five knots of wind had coaxed the sea in Jordan Basin into vast swells that rolled the 300-tonne ship from side to side, sometimes breaking in showers of icy salt water over the bow. The ocean around the boat was steely grey beneath a shower of rain and sleet. The crew of the Endeavor had come to sea to look for whales, but they couldn’t see a thing.
Moira Brown, known to all as Moe, scanned the slate-coloured waves. Brown had spent the past 30 years trying to protect the North Atlantic right whale, the desperately endangered species that was supposed to live in the patch of ocean heaving around them. For most of those 30 years, staring out at the ocean was the only way to find right whales — and, in a storm like this, spotting even one would be close to impossible. Only a few years ago, this research trip might have been cancelled.
But this time, the Endeavor team had a set of ears in the water.
Somewhere in that patch of the Atlantic, a small autonomous vehicle — what most people might call a drone — called a Slocum glider was coasting below the waves. This trip was its maiden voyage, the first opportunity to see if it worked as well as its creators hoped. An underwater microphone on the bottom of its bright yellow, torpedo-shaped body was taking in every sound from the surrounding ocean and storing it on its tiny onboard computer system. When it surfaced, the glider would connect with the Endeavor to tell if it had heard the whales they were looking for.
The North Atlantic right whale is one of the most endangered whale species in the world: whittled down by commercial whaling, slow to reproduce, and, today, threatened by the dual dangers of ship strikes and climate change. In the face of these challenges, scientists are turning to a new generation of drones, equipped to find and identify whales in the vast ocean. Capable of distinguishing between a right whale and a humpback, of staying at sea for months at a time, and of weathering wind and waves, these gliders have become a powerful new tool in studying right whales and protecting them from the dangers they face.
Down in the Endeavor’s lab, illuminated in the dim by the bright glow of his computer, researcher Mark Baumgartner watched as a series of notes arrived on his screen. They started low and pitched upwards at the end, as if their singer were asking a question. The pattern was a familiar one: it was a right whale, calling out somewhere in the storm.
The right whale is a stocky creature, fat and rounded, with an m-shaped mouth that gives it the look of a comically permanent frown. Fully grown, it can weigh up to 70 tonnes and grow over 15 metres long. Its skin is slick and black, broken by patches of rough greyish-white called callosities, which form in reaction to lice that live on their skin. At the surface, right whales exhale in a distinctive spout that splits in a V, drenching anything that happens to be nearby in a fine mist smelling of salt and dead fish.
Popular legend holds that this whale’s name hails from the days when they were considered the “right” whale to hunt; their school-bus-sized bodies are wrapped in a 15cm thick layer of blubber, oil-rich and perfect for fueling lamps and making candles and soap. At the surface, they move like grazing cows, much slower than any good whaler could row, leisurely straining plankton from the water. Conveniently, the right whale floats when it is killed.
Today, there are between 350 and 500 individual North Atlantic right whales left. Though it has been almost 90 years since the last commercial whale boat was launched from North American shores, the local right whale population has not yet recovered. This has more to do with biology than butchering: once they become sexually mature around age ten, females can only reproduce every three years or so — they will spend a year pregnant and then another 8-17 months weaning their calves. The near-extinction of this species by whaling may also have led to limited genetic diversity in the population, which could cause a low birth rate.
As a result, researchers are working urgently to find out more about the North Atlantic right whale, and stringent federal laws protect this species — as of 1991, as laid out in the Final Recovery Plan for the Northern Right Whale, non-research vessels face civil and criminal penalties if they come within 500 yards (roughly 450 metres) of an animal.
Unfortunately, the females needed to rebuild the right whale population are uniquely at risk in the North Atlantic. They spend long periods at the surface with calves, moving slowly, blending in with the dark ocean. When one of these animals surfaces in a shipping lane, large boats often don’t see them, or can’t move fast enough to avoid them. The ship jerks, its propellers tearing through the whale's blubber, leaving long parallel gashes. It’s over in an instant.
Since 1975, the National Oceanic and Atmospheric Administration (NOAA) has recorded 292 confirmed or possible ship strikes on large whales, 38 of which were North Atlantic right whales. And of the 67 right whales reported dead between 1970 and 2007, 24 were killed by ship strikes. Though this number may seem relatively small, the removal of even a single breeding female inhibits the recovery of this fragile population.
“The only time I get to see a whole right whale is when it’s dead on the beach,” says Moe Brown. She is currently the senior scientist at both the Canadian Whale Institute and the New England Aquarium's Edgerton Research Laboratory, where she’s been since 2004. “Compare that to studying bison, elephants, any of the big land animals. You get to see the whole animal! You can see them interacting with their own kind, with their own habitat. You’re not guessing what they’re doing for the other 45 minutes in an hour.”
Brown is somewhat of a legend in the world of right whale research. She’s best known for the decade she spent working almost single-handedly to shift Canadian shipping lanes out of right whale habitats — the first time in history that shipping lanes were amended for the sake of an endangered animal.
In all the time she has spent observing right whales, Brown’s only observations of them have been from the surface, on research boats or planes. Even for someone who has spent decades studying these animals, much of their lives remain a mystery. “Once they dive below the surface, your guess is as good as mine as to what is going on, and I’ve been doing it for 30 years,” Brown says.
Once a right whale dives, it can stay down for as long as 40 minutes and travel for kilometres underwater, making it difficult to predict where it will surface. Biologists have tried to use satellite tags to track animals, but these devices are much harder to attach to a large, moving animal, and are easily knocked off or damaged — this is particularly the case for right whales, which mate in jostling social groups that Brown compares to “dancing in a crowded discotech”.
The final, and perhaps the most daunting, challenge to studying whales is finding them. In the vastness of the ocean, spotting an animal that spends most of its life underwater requires calm waves and clear skies — and the ocean is not known for coordinating its moods with the needs of biologists.
Fortunately, in the early 2000s, a computer-savvy marine biologist was inspired to create a system that is changing all that.
Mark Baumgartner decided to search for whales with drones during a poker game. Every week, Baumgartner and Dave Fratantoni, a fellow researcher at Woods Hole Oceanographic Institution (WHOI), sat down over cards and hashed out the details of what they were working on. One night, after talking about Baumgartner’s work studying why baleen whales feed where they do, Fratantoni wondered aloud if his own expertise could help.
“Have you thought of doing marine mammal work with gliders?” he asked. Fratantoni was one of the early users of underwater Slocum gliders, which he used to collect oceanographic data like water temperature and salinity.
Baumgartner was intrigued. Slocum gliders could be a way to both listen to whales and collect the data he needed on water conditions. They could also stay at sea for three to four months at a time, supporting just the type of surveys Baumgartner wanted to conduct.
When Baumgartner started attaching hydrophones to gliders in 2004 and 2005, recording the sounds of the sea was not an entirely new venture; the US Navy had been using hydrophones to listen for submarines sneaking through the depths since the late 1940s. In the mid-1980s, biologists began using hydrophones to monitor living animals. In those early days, the microphones were often attached to units mounted on the seafloor; Baumgartner was among the first to try one of these devices on a moving platform.
“There were a lot of people who said you couldn’t do it, because the flow noise was going to be too bad,” Baumgartner says. Flow noise, he explains, is the whoosh that you hear when running or biking quickly, as air is pushed past your ear — or water buffets a microphone. Luckily, the Slocum glider moves “even slower than when you’re out on a leisurely Sunday walk”.
Even so, when Baumgartner began reviewing the recordings sent back by the gliders, he found sorting through them difficult and time-consuming. Hours of his tapes consisted of nothing but sand hissing over the bottom, waves slapping at the surface, perhaps the grumble of a ship overhead; a right whale call could be buried at the end of the recording, or difficult to distinguish from that of another species. Baumgartner needed a program that would sort through the calls for him.
With a background in mathematics and computer science, Baumgartner was able to design an algorithm that could turn hours of sound into packets of useful information. He called on WHOI engineers Mark Johnson and Tom Hurst to design a specialised monitoring instrument, and on Fratantoni to help him operate the gliders, and together the team built a new tool: the digital acoustic monitoring instrument, nicknamed the DMON.
Baumgartner’s algorithm is the brains of the operation, capable of sorting whale calls by species. Installed in the system is a library of whale sounds, each species’ song as distinctive as its own language. Every 15 minutes, the DMON compares its recorded calls to those in this library, matching the ones with the highest similarity. The system also produces sets of pitch tracks, visual maps of the calls written out like sheet music. The pitch tracks can be helpful for identifying species like fin whales, which repeat the same note over and over again — almost like the barking of a dog — which the system could misidentify as background noise, but which is unmistakable when written out.
Every two hours, the DMON returns to the surface, where an iridium satellite antenna on its tail beams to Baumgartner’s computer any information it has gathered: pitch tracks, call identifications, and the temperature, salinity, and phytoplankton levels around it, as well a set of GPS coordinates for where it has surfaced. In the vastness of the ocean, indifferent to weather that could scrap traditional scouting methods, the DMON works like a set of MapQuest directions — drawing a line between the researcher and the place where they should start looking for whales.
Moira Brown and Mark Baumgartner met early in Baumgartner’s career, when he was working on his PhD on right whale feeding ecology. The 2012 cruise to Jordan Basin was the first time these scientists worked together directly — and the first time Baumgartner tested the DMON system in the water. Two weeks prior to their cruise, Baumgartner had directed two DMON-equipped gliders towards Jordan Basin as advance scouts. Unruffled by rough seas, the drones picked up calls that led researchers to right whales within three hours of starting their first search.
However, not long after Baumgartner and Brown began using gliders, something changed.
“We started using the technology in areas where we knew right whales were going to show up, mostly trying to understand what is it about the ocean that’s special there?” Baumagartner says. “Well, it turns out that not too long after we started using this technology, right whales stopped showing up in their usual habitats… in the very places we were putting our gliders.”
Roseway Basin, once a major feeding and socialisation zone for right whales, has fallen mostly quiet; right whales might drop in for an hour or two before vanishing once more. Numbers in the Bay of Fundy have varied widely, dropping to 15 right whale sightings from July to December 2013, before swinging back up to 204 in 2014. Lately, right whales have been spotted more frequently than before in the Gulf of Saint Lawrence, between Quebec and Newfoundland, over 640 kilometres north of the animals’ usual habitats.
Scientists believe that the whales may be moving out of hunger. Samples from the Bay of Fundy last year showed an unusually low concentration of the small crustaceans that right whales eat, called copepods. It’s still unclear why these tiny creatures have vanished. However, the sea surface temperature of right whale habitats has increased by 0.5–1ºC over the last century — enough that the food on which copepods rely may have been killed off or moved north, or redistributed by changing ocean circulation patterns. As their prey follows its own food into cooler waters, the right whales have no choice but to follow.
Yet even as rising temperatures reshape the North Atlantic ecosystem, drones can find whales, even when it is unclear where to start looking.
The summer of 2016 seemed poised to prove just how much the North Atlantic was changing. Temperatures spiked past 32ºC for several weeks in a row; despite arduously high humidity, New England fell into one of the worst droughts it had seen in years. Fortunately, the DMON system’s four years of ground-proofing meant it was ready to tell scientists just how right whales were adapting.
Starting in late June, scientists at Dalhousie University in Nova Scotia and partners in the US — including Baumgartner — launched the largest survey of right whales in the North Atlantic ever attempted. DMON-equipped Slocum gliders, supported by aerial surveys and acoustic listening buoys, spent the summer collecting the information needed to establish where right whales were feeding, and why they might have moved there.
While data from this effort are still being processed — to analyse the effects of parameters like food supply, oceanographic changes, and habitat characteristics — the vocalisation data that have come in so far confirm that this summer followed the right whale’s unusual trend of late. By the end of last month, the glider in the Gulf of Saint Lawrence had identified 20 confirmed right whale calls since July 24, while the glider off the coast of Nova Scotia — which was put in the water a month earlier — had only detected eight.
On 7 December 2015 — around three years after his first DMON deployment on Jordan’s Bank — Mark Baumgartner stood ready on the back of the research vessel Auk, a boat hook in hand. His eyes were focused intently on what looked like a bright yellow model airplane growing closer off the ship’s port side: a Slocum glider, held at the surface by an airbag inflated in its tail. The Auk was bobbing gently in the Stellwagen Marine Sanctuary off Scituate, Massachusetts, as its crew prepared to recover a glider and deploy a new one in its place.
The glider was hauled on deck, knee-high waves soaking Baumgartner’s jeans. The vehicle had been at sea for five weeks, but didn’t look much affected by the trip: it was faintly smudged with brown from seaweed, but was otherwise almost identical to the glider being deployed in its place. The tail of the second glider read 10 rather than 4, and a message scrawled on its side in marker pen requested that nobody disturb the vehicle unless found after 22 January 2016. Surprisingly, such messages are necessary — last year a fisherman picked up a glider during its brief surface interval, thinking it was adrift. “I tracked the GPS signals all the way to the guy’s house,” Baumgartner recalls. “He had just posted it on the marine salvage site when we knocked on the door.”
Equipped with a suite of oceanographic tools, as well as its warning message for fisherman, the second glider was programmed to pick up where its counterpart had left off, tracking a zig-zag path between this spot outside of Scituate and the waters west of Salem. Naturally, it would be listening as it travelled.
Given the huge problems that right whales face, the bits of data that these gliders collect may seem incredibly small. Yet whale calls and GPS points, water temperatures and plankton counts are slowly painting a picture of the new world in which right whales live, making it possible for scientists and ships alike to adjust. There is hope for the right whale yet in data: in Glider 4, dripping seawater onto the Auk’s deck, and in Glider 10, as the ship’s crew slid it gracefully into the chilly Atlantic.
Baumgartner’s vision for the DMON system extends well beyond monitoring individual habitats like Stellwagen. He imagines a network of floats installed in oceans worldwide and equipped with call-identification software, capable of listening for marine mammals and creating a global map of how species are migrating year-to-year.
“That’s kind of my pie-in-the-sky idea,” Baumgartner says. “If we could have a global distribution of listening devices, we’d be ready as scientists to document how the animals in the ocean are going to change their distribution, their behaviour, with the changes that we know are coming.”
As Baumgartner prepared the second glider for its first dive, suddenly someone spotted an enormous splash off the ship’s starboard side. It was a pair of humpback whales, the last few that had not yet begun the annual migration to warmer waters, breaching in the distance. While the drone became a fading spot of yellow beneath the water, off to go eavesdrop on whales, the crew paused a moment to watch them, seemingly jumping for the joy of it.
Edited by Andrew Katsis and Ellie Michaelides