The gray whale travels on one of the longest migrations of any animal in the world. (illustration credit ill.9)
GRAY WHALES JUST look like survivors. Their slate-colored skin is crusted with barnacles, and their huge, scarred jaws curve downward in what seem to be permanent grimaces. Bottom-feeders who mostly eat tiny crustaceans, these creatures nevertheless have a reputation as formidable fighters. Only packs of orcas and humans usually dare to hunt them, and accounts going back several centuries describe the deadly wrath of grays pursued by whalers. In 1874, the whaler and naturalist Charles Melville Scammon wrote about his experiences hunting grays. He recalled, “Hardly a day passes but there is upsetting or staving of boats, the crews receiving bruises, cuts, and, in many instances, having limbs broken; and repeated accidents have happened in which men have been instantly killed, or received mortal injury.” Grays, he explained, possessed “unusual sagacity,” which made them a hard target—especially when the animals’ intelligence was coupled with their 35-to-50-foot lengths, 80,000-pound bodies, and “quick and deviating movements.”
Despite their ferocity, grays have one vulnerability. Every winter, they migrate thousands of kilometers from the safety of their Arctic Ocean feeding grounds to a series of warm lagoons in Baja California, Mexico. One of the most popular spots is nicknamed Scammon’s Lagoon, after the whaler. Theirs is close to the longest migration taken by any animal on the planet, and the whales will encounter many predators and treacherous conditions along the way. Then, after a winter spent having children (and making them) in the lagoons, they begin the trip back up the coast again, often tailed by their young. Though both the Arctic Ocean and Mexican lagoons are relatively sheltered from predators by natural barriers, the long migrations in between leave the whales exposed to danger for months at a time. How do they manage?
The gray whale travels on one of the longest migrations of any animal in the world. (illustration credit ill.9)
Grays have evolved a number of features that seem to protect them during their migrations. Remarkably, the whales never stop swimming during these journeys. Their brains “sleep” by shutting down only one hemisphere at a time, so one part of the gray’s brain is always awake to keep it moving in the right direction. Even more unbelievably, grays rarely pause to feed during their migration. Instead they live on stored energy. They’ve spent the entire summer grazing on the Arctic seafloor, building up a thick layer of energy-storing blubber which they burn through during the roughly seven-month round-trip to Mexico. Grays eat by taking giant bites of dirt and sifting tasty crustaceans out through the baleen filters in their mouths. This is why they’re often seen with big, muddy smears on their lips after they eat. Marine biologists often jokingly call them the cows of the sea. Grays spend half the year eating so that they can spend the other half migrating and reproducing.
It’s likely that grays have been living this way for the many millennia since they first evolved 2.5 million years ago. Grays are also slightly less complex than some other cetaceans, which has led some biologists to speculate that they are a more ancient species. They don’t “sing” by creating complex harmonies like humpback whales do. They emit what scientists call moaning noises that can be heard only at close range—unlike humpback songs, which can be heard for kilometers underwater. Though grays are able learners, as Scammon observed over a century ago, they don’t exhibit a lot of social behavior like their cetacean cousins the dolphins. Instead of swimming in pods, they prefer to migrate in loose, ever-changing groups of two or three. Many travel alone. Still, grays have maintained what could be called a tradition, their great migration, that gets passed from one generation to the next. This isn’t a matter of mere instinct. Scientists believe it’s something that each new generation of juveniles must learn from the adults, like passing along a map that is vital to the survival of the species. It’s therefore no exaggeration to say that grays survive by relying on their memories. Without memory, they would never find food, nor enjoy a mating season.
Humans nearly drove gray whales to extinction in the early twentieth century, but thanks to one of the earliest conservation agreements in the world, the gray population today has rebounded to what it may have been before whalers thinned the animals’ ranks. The story of gray whale survival offers us two lessons. It teaches us the importance of passing along knowledge from one generation to the next, and it shows us one sure way to stop extinction in its tracks.
People have been observing gray whales for centuries, but there are still many aspects of these creatures’ lives that remain a mystery. Often, we only catch glimpses of their behavior when the whales are in trouble, straying from their usual paths. This was certainly the case in 1988, when an Inuit whaler spotted a group of three grays stranded in the Arctic waters. It was so late in the season that ice had blocked their path out to the northern Pacific. Grays begin their southern migration when the Arctic starts to freeze. If they stay to graze a little too long, they get boxed in by ice that’s formed over the top of the ocean. With no room for the animals to surface and breathe, the straggler grays drown. It happens to a few whales every year, and locals are used to seeing their bodies wash ashore after the ice retreats in summer. But these grays hadn’t drowned yet—in fact, all three (including a small calf) were surfacing to breathe out of a small open hole in the ice. Footage of their struggle to survive captured national attention, bringing television crews and scientists flocking to the small Alaska town where the creatures were stranded.
A young biologist named Jim Harvey came too, trying to reconcile the behavior of these grays with what he’d seen before. These three were clearly working together to share the airhole and survive, though typically grays are solitary creatures. What’s more, the grays seemed to figure out that the humans jumping up and down on the ice around their hole wanted to help them. Eventually, after forces from both the Soviet Union and the United States got involved in the quest to free the whales, the grays followed an icebreaker out to the open sea. Harvey, now a professor at Moss Landing Marine Laboratories (MLML) on Monterey Bay, has spent the decades since the incident studying marine mammals and other creatures that make a home on the shoreline.
When I visited Harvey at MLML, a cluster of artfully designed, recycled wood buildings built just a few yards from the waters of the bay, the door and windows in his office were thrown open. Outside, seabirds skimmed over the sunny water, and grass furred the sand dunes. Further out to sea, sea lions barked and frolicked in waters where the grays travel twice a year. For decades, Monterey Bay has been a prime spot for gray whale observation—it seems to be a favorite place for the whales. Here they swim very close to shore, making it easy to take population counts and watch them in the wild.
From decades of observation, it’s become clear that the whales don’t choose just one group of companions for the whole migration. “They’ll be with a bunch of animals, forming and changing groups all the time,” Harvey told me. “It’s like being in a bicycle race. You can draft behind [the leader], and it’s nice to be in a group because the guy in front is usually paying attention. I think gray whales do that, too. They trade positions in terms of paying attention.” Harvey had just come in from a run along the water, where he’d followed a narrow trail between MLML, a few other local marine-biology labs, and the undeveloped coastline.
His mind still on the dynamics of racing, Harvey pondered a question that is hotly contested among biologists. How, exactly, do the grays learn to navigate their way along all those thousands of kilometers of coastline? “I’m purely speculating,” he said, “but I think they’re following each other, and somebody else follows them, and they remember it.” When I asked whether they’re communicating directions with sound, too, he shook his head. “I’m sure they don’t talk to each other. They’re just following each other.” Young whales always make the trip with an animal that has gone before.
Still, the trip changes year by year; grays are constantly tweaking their route. Twenty years ago, most of the grays migrated along a path that took them inside the Channel Islands, and closer to the coastal cities of Santa Barbara and Los Angeles. The problem was that they stuck to the shoreline too closely, often following it all the way into the shallow waters where they would become trapped. Grays have had similar problems getting lost in San Francisco Bay and Monterey Bay when they chart their course using what Harvey jokingly referred to as the “keep the shoreline on the left” method. But today, their routes take them outside the Channel Islands, and often outside San Francisco Bay too. “So they’ve figured it out,” Harvey said. They realized that more direct routes away from the coast would be faster and less dangerous, and passed that information on. Grays live for about 50 to 70 years, so these course corrections are taking place within the lifespan of a typical animal.
More recently, Harvey and a National Oceanic and Atmospheric Administration (NOAA) biologist named Wayne Perryman have observed that grays are migrating later in the year, possibly because melting Arctic ice means they have to go farther north to find good grazing grounds. As a result, a faster route south is going to become more desirable to the grays as the years go by—they need to cut corners, as it were. But this longer route is also changing a lot more than their maps to the south. In 2012, observers were surprised to find a female gray and her very young calf swimming in San Francisco Bay. Given the age of the calf, Harvey and Perryman estimated that the gray had probably given birth en route to Mexico. She’d left the Arctic so late in the season that she wasn’t able to get there in time to have her baby. It’s possible that the melting Arctic ice will dramatically change the migratory cycles of the Pacific grays, altering the map that one generation of whales passes along to the next. This is another clue that the grays navigate their migratory routes by learning and memory—if the trip were somehow hardwired into their brains, they wouldn’t be able to shift its parameters every year depending on environmental conditions.
Of course, some grays don’t manage to remember the route quite right—which is why, for example, those three grays got caught in the frozen Arctic in 1988 and had to be rescued by icebreakers. This leads Harvey to another big question. Why should the grays continue to migrate at all, as the thawing Arctic slowly becomes more habitable year-round? “It might get to a point when they don’t have to go, but the reality is that the water is still cold,” he mused. And staying warm in winter Arctic waters takes a lot of energy. He and his colleagues believe it’s worth it for the whales to swim all the way down to Mexico and save energy in the warm water, rather than not swimming but remaining in the cold water.
This also helps to explain why juvenile whales make the journey down to Mexico, even though they are still too young to participate in the mating and calving that goes on in the lagoons. To get the most out of all the blubber they’ve been building up in summer, the young whales need to seek out warmer waters with their elders. But there’s another benefit, too. “Eventually, if you want to be part of the reproductive group, you need to know how to do the migration,” Harvey explained. “They are gaining knowledge, including reproductive knowledge, by making the journey.” It’s likely that the young whales are learning another survival skill along with the route south and then north again. When they arrive in Mexico they’re watching other grays reproduce. How whales learn to mate is a big question mark scientifically, but Harvey said it’s possible that they do it the same way they learn to migrate: through observation and memory.
Unfortunately, memory is no defense against the concerted efforts of ships full of people with harpoons and explosives. The descendants of the whales Scammon hunted still roam the waters of the Pacific coast, but their now-extinct relatives in the Atlantic weren’t as lucky. A large group of grays lived in the Atlantic for thousands of years, migrating from the Arctic to the Mediterranean. But historical evidence suggests that they succumbed to hunters in the eighteenth century. Today, there are only two groups of gray whales left. One, the eastern Pacific, or California-Chukchi group, whose migration we’ve talked about up to this point, contains perhaps 20,000–30,000 individuals. The other is a small, poorly understood group of roughly 200 individuals called the western Pacific or Korean-Okhotsk grays. These whales have a different migration route, along the coast of Asia. In summer they graze along coastlines in the Sea of Okhotsk off the coast of Russia, above Korea and Japan. Their calving grounds are off the coast of Korea.
Both these groups would have gone the way of their Atlantic cousins if it hadn’t been for the rise of conservation groups in California during the early twentieth century. After the establishment of groups like the Sierra Club, which helped protect Yosemite National Park from development in the late nineteenth century, the burgeoning environmentalist movement began to think about protecting animals as well as environments. Even whalers like Scammon noted with unhappiness that the whales were going to be exterminated if hunting kept up at the pace he observed. Often, hunters would simply plow into the mating lagoons and slaughter the vulnerable mothers and calves, destroying the population’s ability to reproduce. Disturbed by the inhumanity of these hunting practices, and aware that grays weren’t particularly valuable as commodities, in 1949 the newly formed International Whaling Commission outlawed the hunting of gray whales. Since that time, many scientists believe that the eastern Pacific population has bounced back to what it might have been before whaling started. Others argue, based on genetic data, that it’s likely the original population before whaling was closer to 90,000 individuals.
Regardless of what the original population was, marine biologists who study the whales seem to agree that the California grays have rebounded in an extraordinary fashion. Over the past 60 years, they’ve gone from near extinction to a healthy, diverse group capable of learning new migratory strategies to cope with changing conditions in the Arctic. Their growing population numbers stand in stark contrast to those of other whales, especially ones like the right whale, humpback, and blue whale that navigate their own great migrations every year. Several studies suggest that noise pollution in the water from radar, and human encroachment into their territories, may be disorienting these whales. This leaves them vulnerable to beaching, or injuring themselves by swimming straight into large ships.
Grays were saved from extinction because humans chose to change their behavior. It’s possible that humans might save other whales from extinction, too, by changing our behavior in the same way. We could avoid using frequencies that whales prefer for their sonar. Or we could track whale migratory patterns using satellites—something that many scientists do already—and avoid creating shipping lanes near the areas where whales are making their journeys. Changing the way we use sonar is obviously more difficult than outlawing whale hunting. But it is certainly possible, and today’s gray whale population is a reminder that extinction is not inevitable for these massive sea mammals.
There’s another reason grays are good survivors, though. Their migratory patterns keep them relatively safe and well fed. Few animals compete with them for food in their Arctic Ocean hunting grounds, which are vast and well stocked. Humpbacks, by contrast, feed in a small coastal area, which Harvey calls “a very compressed region.” If they can’t find prey in that region, humpbacks suffer. But the grays have found an enormous feeding ground where they can chomp on the seafloor during summer, as well as a protected place to mate in winter. And they’ve carefully charted a route between the two places that’s as safe as possible. Traveling along the coasts, their large bodies are generally hidden from predators by the sounds of the surf and the dirty, silty water they love. Their lack of sonar may mean that grays are more solitary, simple creatures than some other cetaceans. But this simplicity has helped them rebound from extinction, while whales with more complex communication and social structures are suffering.
Still, the grays would never have made it this far without their ability to pass along a survival map from one generation to the next. As long as they keep learning new ways to survive the arduous Pacific coastal migration, the grays will endure.
Nomadic humans survived for thousands of years in a similar way, wandering across vast regions to find food and good seasonal weather. Many human tribal groups had traditions where they met once or twice each year for large gatherings, not unlike what the grays do when they converge in the Mexican lagoons. At these gatherings, nomadic humans would exchange gifts, pass on stories, and find people to marry outside their bands. Today, however, human survival can’t hinge on migratory patterns. Most humans live in settled communities and cities, and the knowledge we pass on to the next generation is infinitely more complex than a migratory route or information about where to find the most abundant food. We’ve learned so much that we need libraries and databases to augment our memories.
Still, the grays have a lesson to teach us about the role of memory in survival. This struck me forcefully one afternoon in Monterey Bay, when I joined a whale-watching group in a small boat that fought its way over wind-whipped waves in search of the elusive migrating grays. The most adventurous of us made our way to the bow with our cameras, clinging to the railings and getting completely soaked by spray. We were joined by several large schools of porpoises. A group of four kept jumping out of the waves at the same time in graceful synchrony, as if trying to make it clear to the ridiculous monkeys who really belonged out here. But we kept scanning the horizon for grays, hoping to see their characteristic spouts. At last, just when we were about to retreat, we spotted one. The whale slid its blowhole just above the waves, most of its great bulk obscured by water and distance, and disappeared again. We all jumped up and down, pointing and forgetting to take pictures in our excitement. Just the sight of such a magnificent creature filled us with crazy awe, and all the sopping people in the bow started bonding and swapping stories of other amazing animals we’d seen. One person had seen a Bengal tiger in the wild, and another had been in Mexico to see the grays in their winter home. Nobody forgets these kinds of sightings because most of us, no matter how much we love urban life and civilization, also deeply love nature.
Like grays, humans are good survivors because we’ve learned to find food and homes across a vast region of the planet. Also like grays, we’ve learned to traverse these territories in more efficient ways, responding to changes in the environment. We’ve figured out how to build cities that protect us better than villages did; we’ve passed along stories of how to survive best on what is still a dangerous planet. Sometimes, we’ve even changed our behavior to protect life-forms other than ourselves. As we turn to the next part of this book, about planning for the future, we’re going to remember the grays’ lesson: You’re always coming home, but the path to get there is going to change all the time.