To save endangered whales, look to the poop
Dung holds clues about noise pollution and lack of food.
When Samuel Wasser and his colleagues first took to the ocean in search of whale poop, they discovered that this unusual pastime can lead to the occasional misunderstanding. One day, they were noticed by a county sheriff on the prowl for drug runners. “He came up to us and he thought he had caught us,” says Wasser, who is director of the Center for Conservation Biology at the University of Washington in Seattle. The team explained that the dog in their boat was sniffing for a material that most people would have little use for.
“You’re pulling my leg,” the sheriff finally said. For a time, he watched the scientists from a distance. Then he steered his boat away, and left them to their work.
That work can reveal a lot about animals that are enormous and difficult for scientists to track and study. The poop that whales leave floating in their wake is chock full of information. It carries remnants of hormones, pollutants, gut microbes, and DNA from the whale and its prey. It can reveal how stressed a whale is, or whether it’s pregnant.
“There really is no other way to learn about what I call the inner whale—to learn about their physiology,” says Rosalind Rolland, a senior scientist at the Anderson Cabot Center for Ocean Life at the New England Aquarium in Boston.
By now, Rolland has perused hormones in the poop of five whale species, and is expanding to northern fur seals, sea lions, and West Indian manatees. She and other scientists have been scooping whale poop since 1999. Now, their hard, smelly work has begun to bear fruit. Fecal samples are offering evidence about how these marine mammals are threatened by noise or lack of food, or what parasites and toxins they’ve picked up. These observations, researchers hope, will help them figure out how to save endangered whales.
Searching for treasure
Of course, poop isn’t the only material that scientists use to examine wildlife. But drawing blood can stress an animal out, and wrangling huge whales isn’t practical. Poop, however, is there for the taking. “It’s just a huge amount of information that was never available before without having access to a whale that was either killed by whalers or stranded and died,” Rolland says.
And because collecting poop doesn’t bother the whale, scientists can harvest dung from the same animal repeatedly. “You can collect samples over and over again…without invasively harming them,” says Leigh Torres, a marine ecologist at Oregon State University in Corvallis. “It’s a biological goldmine.”
This precious material looks and smells a little different depending on which whale it came from. The endangered North Atlantic right whale, which was the focus of early poop scooping efforts, happens to have very distinctive stool. It tends to be bright orange, likely due to the whales’ diet of tiny crustaceans called copepods, says Kathleen Hunt, a biologist at Northern Arizona University in Flagstaff, who has often collaborated with Rolland. It also floats, unlike the leavings of some other species. “It’s helpful because…you can spot it more easily when it’s bobbing around,” she says. On the other hand, “It has the worst stink of any type of fecal sample I’ve ever worked with.”
But that rancid, fishy aroma is actually great news for scientists. “It’s almost like it was designed to be really obvious,” Hunt says. “Just by pure luck, we started with the very best poop.”
Besides, she doesn’t mind the stench so much anymore. “After years of dealing with right whale poops in the lab you actually do get used to the smell,” she says. “It gets so I’m merrily carrying around this little bag of whale poop…and people down the hall, around a corner are complaining to me that it smells so bad that they can’t work.”
Meanwhile, the gray whales that Torres tracks expel a reddish or brownish plume of poop. She and her colleagues have only about 30 seconds to swipe as much as possible into their fine mesh nets before it sinks. “It has an odor of the ocean,” she says. “It doesn’t smell as bad as their breath.”
Sometimes only a thimbleful of poop can be collected before the choppy water pulls it all apart, Wasser says. Poop from the orcas he studies ranges from light brown to dark green and smells of salmon. “It’s not too different in color from the water,” he says. “It is not so easy to see.”
Luckily, he has dogs to help hunt down the doo-doo. Wasser trains high-energy dogs rescued from shelters to zero in on scat from whales and other threatened and endangered animals. These dogs’ “insatiable” urge to play means they aren’t likely to get adopted, but makes them dedicated workers. They can catch a whiff of poop nearly a mile away. Once Wasser and his team have been steered to their quarry, the excited dogs are rewarded with a ball.
Unfortunately, whales do not poop on command. “You’re at the mercy of the animals’ digestive tract about when a sample will appear,” Hunt says. It takes years of waiting and scooping to collect enough poop to make any inferences about the animals.
There are other ways of getting whale excreta. Researchers are pioneering drones called SnotBots to capture vapor exhaled from the animals’ blowholes. Whale snot is available whenever you want it. But it’s also diluted by seawater, making it more difficult to analyze.
Life in the noisy seas
Poop can offer some insights about how whales are impacted by noise pollution. Whales rely on sound to navigate, hunt, and communicate, Torres says. So the louder the ocean gets thanks to ship traffic, sonar, and seismic oil and gas exploration, the harder it is for whales to conduct their normal lives.
The experience might be akin to spending all your time in a noisy nightclub, Hunt speculates. “You could still walk around, you can still eat, you can still talk to your friends—but you’re having to shout, your ears are ringing, it’s kind of exhausting.”
We know that spending prolonged time in noisy environments is stressful and unhealthy for humans. Scientists suspect that whales are similarly harmed, and have observed the animals clam up or vacate noisy areas. But it’s difficult to link noise to changes within the whales’ bodies.
“You can’t just announce to the whole eastern seaboard, ‘okay we’re all going to stop driving boats around for two weeks,’” Hunt says. “It’s very hard to study what it would be like without that ocean noise.”
She, Rolland, Wasser and their other colleagues have only had such an opportunity once, and it was not one they expected or would have hoped for. In the days following 9/11, both plane and ship traffic were disrupted. Rolland and her colleagues happened to be studying right whales that month in the Bay of Fundy, which lies northeast of the coast of Maine. “After September 11, we decided to continue our work despite what had happened,” she says. They took acoustic recordings of the bay, collected whale poop, and perused ship traffic logs.
After 9/11, boat noise plummeted—as did the amounts of stress-related hormones in the whales’ poop. The team could not find a similar drop in stress hormones in the four years that followed. The constant drone of ship noise, their work indicated, is chronically stressful for whales.
Torres is also interested in how noise pollution harms whales. She has been collecting poop from gray whales near the coast of Oregon, which are exposed to ship traffic and the natural sounds of storms and waves, for several years. Her team is also gathering poop from blue whales in New Zealand. In this area, it’s common to find ships searching for oil under the seafloor by pounding it with pulses of sound and listening for the echo.
Over time, Torres hopes to create a picture of how stress hormones normally vary. Cortisol, the hormone she and her colleagues are most interested in, can rise or fall depending on the whale, how much food it had access to, or whether it is pregnant. “Once we sort of hammer those trends out then we can add in the noise component,” she says. The team is also tracking how plump and well fed the whales are, and how noisy the seascape is over time.
Eventually, she hopes, their understanding of stress hormones could also be applied to whales that are too elusive or endangered to offer much poop.
Noise is not the only human-linked stressor whales must contend with. Wasser currently studies the southern resident killer whales, an endangered community that spends the summer and fall off the coasts of British Columbia, Washington, and Oregon. There were about 90 of these whales in 2005, when the group was first listed as endangered. They have continued to decline since then, and now there are only 78 individuals.
There are three possible culprits behind the whales’ difficulty. They could be disturbed by vessel traffic, or they may be exposed to toxic chemicals. And then there are the Chinook salmon. The southern resident killer whales prefer this largest, fattiest of salmon. So do people—Chinook salmon are overfished, leaving scant prey for the whales. “You’ve got an endangered population of whales eating an endangered species of fish,” Wasser says. This lack of prey, Wasser’s scatological research suggests, is the chief reason that the killer whales are faring poorly.
Over the years, he and his colleagues have seen fewer calves than would be expected born to the 30 or so adult females in this population. So they’ve been giving the whales a pregnancy test—signs of the hormones progesterone and testosterone in droppings can reveal whether a whale is pregnant and how far along she is. Nearly 70 percent of the pregnancies Wasser and his crew detected ended in miscarriages or stillbirths.
If an animal is going to miscarry, this usually happens early on. But a surprisingly high number of the orcas’ pregnancies failed late in gestation. This indicates the whales were capable of conceiving, but not holding onto their pregnancies.
The reason: not enough food. Wasser and his team checked the balance of two hormones in scat from females that had successful pregnancies and those that didn’t. Thyroid hormone helps control metabolism; when food is scarce, an animal will secrete less of it. That “kind of puts the breaks on and slows things down, so you last longer until you can find food,” Wasser says. Cortisol also plays a role in nutrition. In a crisis, this hormone mobilizes glucose to give an animal energy.
The unlucky whales had relatively high amounts of cortisol compared with low amounts of thyroid hormone. These whales, the team concluded, were chronically underfed. And, as Hunt explains, “They can’t make a baby if they don’t have enough fat and blubber.” To give these killer whales a chance to thrive, we’ll also need to conserve their salmon prey.
As Hunt, Rolland, and Torres have found, stress hormones like cortisol can also be a sign that whales are disturbed by noisy surroundings. But for Wasser’s orcas, the lack of food seems to be even more important. Stress hormones in the whales’ poop ebb each year in mid-August, just when the salmon are most plentiful—and when boats are also most likely to be out, taking advantage of the nice weather.
The lack of food also may exacerbate the harms wrought by any pollutants the whales encounter. Females that miscarried late in their pregnancies also had higher concentrations in their poop of PCBs, chemicals that linger today in some building materials and other products. Many pollutants build up in an animal’s fatty tissue. “As they run out of food and burn fat, it dumps the toxins into the bloodstream,” Wasser says.
It’s all in the poop
With poop, scientists have found, one can probe many different stressors faced by whales. That means they can gather evidence of how whales suffer from the din of human noise or loss of vital prey. Rolland is also examining neurotoxins made by algae, including those responsible for red tide, and water-borne parasites such as giardia in right whale poop.
It’s important to get a handle on all these different trials, because climate change is likely to bring even more sweeping, intractable changes. Already, right whales are showing up less often in the Bay of Fundy, Hunt says. This suggests they are following their tiny crustacean prey as it is driven northward by rising sea temperatures.
“If we can still relieve the pressure on the [whales] from all of these other impacts, including the ocean noise, then they have a better chance of being able to respond nimbly to this big change of the food all moving,” she says.
This is a formidable challenge—noise pollution has risen over the past few decades, and today 90 percent of world trade is carried out by cargo ships. But boats can be made a little less loud, which would benefit their human owners as well. “A noisy engine is an inefficient engine,” Hunt says. There are other incentives, too; the Port of Vancouver has cut docking fees for quieter ships. Many of the other whales’ challenges can likewise be tackled with ingenuity and compromise, scientists hope.
A first step, though, is understanding the mark they leave behind in whale poop. That means collecting hundreds of bags of whale droppings, year after year. It’s stinky but thrilling work. “Anytime the whale poops it’s pretty exciting,” Torres says, “because I know it’s another great look into the animal’s biology.”