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Crocs Uncover
Bizarre Species
lunes, 6 de octubre de 2008
Right Whales
By Douglas H. Chadwick
Photograph by Brian Skerry
They dive 600 feet, brushing their heads along the seafloor with raised, wartlike patches of skin, sometimes swimming upside down, big as sunken galleons, hot-blooded and holding their breath in cold and utter darkness while the greatest tides on Earth surge by. Then they open their cavernous maws to let the currents sweep food straight in. This is one way North Atlantic right whales feed in the Bay of Fundy between Maine, New Brunswick, and Nova Scotia. Or so the experts suspect, having watched the 40- to 80-ton animals surface with mud on their crowns. Mind you, they say, that could result from another activity—one nobody can imagine yet.
Science calls these animals Eubalaena glacialis, "good, or true, whale of the ice." Heavy irony is embedded in the common name, right whale, given by whalers who declared them the right whales to kill. Favoring shallow coastal waters, they passed close to ports, swam slowly, and often lingered on the surface. Such traits made them easy to harpoon, and they tended to conveniently float after they died, thanks to their exceptionally thick blubber layer, which whalers rendered into oil. The first of the great whales to be hunted commercially, E. glacialis lit the lamps of the Old World from the Dark Ages through the Renaissance. By the 16th century Europeans had exhausted the eastern North Atlantic population and turned to North America's coast. There whalers set up stations in Labrador and took 25,000 to 40,000 related bowhead whales along with an unknown number of rights (records seldom distinguished between these two similar looking titans).
By the time New Englanders got into the right-whale-killing business, they were chasing leftovers. The Yankees hunted down another 5,000 or so, partly because whales became even more prized for their baleen than for oil. Hundreds of strips of this tough yet flexible material, each six to nine feet long and finely fringed, drape from the upper jaw. They form a colossal sieve that allows the giants to strain tiny crustaceans from the water for food—a billion flea-size copepods a day to supply the minimum 400,000 calories an adult whale needs (the ratio of a whale's body mass to its prey's is 50 billion to one). Society, however, thought baleen was best used for corset stays, stiffeners in fashionable gowns, umbrella ribs, and (consider: "I'm going to whale on you!") horsewhips.
As the 20th century began, the number of whales left in this species was possibly in the low dozens. Commercial harpooning wasn't banned until 1935. Their recovery since then might be compared to that of a human victim of a vicious assault: painfully slow progress, offset by relapses, with the ultimate outcome very uncertain.
About 350 to 400 North Atlantic right whales exist today. The survivors migrate along North America's East Coast between feeding grounds in the Gulf of Maine and wintering sites farther south—roughly 1,400 miles one way for pregnant females that journey to traditional calving areas off Georgia and Florida. They travel through an intensely urban stretch of ocean.
A research team from Boston's New England Aquarium spends the summer stationed in Lubec, Maine, studying the whales that gather to feed and socialize in the Bay of Fundy and nearby Roseway Basin, off Nova Scotia's southern tip. The scientists, who have built an archive of around 390,000 photographs, can recognize nearly every whale in the population by its unique callosity pattern (those wartlike patches on their heads), along with scars and other irregularities, and, increasingly, DNA samples.
One of their favorites is #2223, first seen in these waters in 1992. It was a baby, and so fond of cavorting around boats that they named it Calvin after the mischief-loving cartoon kid. That same year a fisherman reported a calf circling its dying mother, and when the team recovered the carcass of the female, they identified her as #1223—Delilah, Calvin's mom. Her corpse revealed tissues crushed by a powerful collision, probably with one of the cargo carriers plying the shipping channel that used to run straight through the bay's center, where the whales concentrate. The eight-month-old calf 's prospects looked grim, for it should have been nursing Delilah's rich, warm milk for several more months.
In July 1993 researchers poring over fresh photos from the bay found images that looked like a match for Calvin's baby pictures. Yes! The orphan had somehow made it alone. DNA from a skin sample taken in 1994 showed that curious, hardy Calvin was in fact a girl whale. The following year brought the first report of her entering a surface-active group, or SAG, in which both sexes mingle with splashing, shoving, rolling, stroking signs of courtship. Though she wouldn't mature sexually until about ten years of age, subadults her age appear drawn to the excitement of SAGs and get to practice behavior that may soon influence their breeding success. Fertile adult females are the most valuable segment of the population. They number fewer than a hundred. Calvin seemed on the verge of adding one more to their ranks.
For three years running, the researchers gauged the young female's blubber thickness with ultrasound. It's a tricky operation. "One whale's reaction jolted the skiff hard enough to send me flying overboard," Amy Knowlton of the research team recalled. Nevertheless, the researchers found Calvin growing pleasingly plump, a prime measure of health. On New Year's Eve of 1999, she was recorded for the first time in the Georgia Bight, an expanse of shallow coastal waters off Georgia and Florida, where right whales give birth.
In summer of 2000 Calvin was once again in the Bay of Fundy, but this time she was snarled in fishing gear. Unbreakable polyblend ropes wrapped round her body, cut into the skin, and trailed in her wake, slowing her down. Then researchers lost sight of the young female.
Two to six right whales are found dead in a typical year, at least half of them killed by ship strikes or entanglement. Additional animals simply disappear. Since more than three-quarters of North Atlantic right whales bear scars from encounters with fishing gear, scientists wonder: How many of those missing are weighed down by ropes, nets, or crab and lobster pots for months or even years, the fat reserves that help keep them buoyant dwindling as they starve, fighting harder to reach the surface for each breath, until they finally give in to pain and exhaustion and sink?
Months dragged by. Someone finally spotted Calvin in Cape Cod Bay during her hobbled journey back south. A disentanglement team from nearby Provincetown, Massachusetts, raced for the site and made two attempts to slice away her bindings. They couldn't get them all, but when Calvin was seen during 2001, she had worked free of the remnants.
Three years passed, and Calvin showed up occasionally—but not in her usual summer haunts. Had the trauma sent her into a downward spiral? At the end of December 2004, near the North Carolina coast, she presented herself—with a brand new calf. Seven months later, in 2005, they were in the Bay of Fundy, where Delilah had brought Calvin as an infant.
The corridor traveled by Calvin and the other North Atlantic right whales has grown ever more crowded with fishing activities and busy shipping lanes. Plumes of contaminants flow from river mouths, and the underwater din of ship traffic probably makes it increasingly difficult for the whales to communicate and keep track of one another. Though not as visible as wounds from boat prows and propeller blades or fishing gear webbed around struggling bodies, heavy chemical and noise pollution may take a gradual toll.
During the 1980s the number of babies born annually was around 12. The total twice fell sharply in the 1990s until just a single calf appeared in 2000. Since then, the average has risen to more than 20 calves a year. Yet this remains 30 percent below the whales' potential rate of reproduction. Why? If scientists are to guide the species' salvation, they need more data and more answers. Fast.
One August morning in 2006, when the sea was a sheet of dimpled satin shot through with silver threads, I joined Scott Kraus, the New England Aquarium's vice president of research, and Rosalind Rolland, a veterinarian and senior scientist with the aquarium, on an unlikely quest in the Bay of Fundy. When leviathans rose in the distance through the sea's shimmering skin, Kraus steered the boat downwind of where they had briefly surfaced, handed me a data sheet to log our movements, and zigzagged into the faint breeze. Rolland moved onto the bow. Beside her was Fargo, the world's premier whale-poop-sniffing dog.
Fargo began to pace from starboard to port, nostrils flaring. Rolland focused on the rottweiler's tail. If it began to move, it would mean he had picked up a scent—and he could do that a nautical mile away. Twitch … Twitch … Wag, wag. "Starboard," Rolland called to Kraus. "A little more. Nope, too far. Turn to port. OK, he's back on it." A quarter of an hour ran by like the bay's currents. All I saw were clumps of seaweed. Suddenly, the dog sat and turned to fix Rolland with a look. We stopped, and out of the vast ocean horizon came a single chunk of digested whale chow, bobbing along mostly submerged, ready to sink from view or dissolve altogether within minutes.
Kraus grabbed the dip net and scooped up the fragrant blob. You'd have thought he was landing a fabulous fish. "At first, people are incredulous. Then come the inevitable jokes. But this," said the man who has led North Atlantic right whale research for three decades, "is actually some of the best science we've done."
With today's technology, DNA from sloughed-off intestinal cells in a dung sample can identify the individual that produced it. Residues of hormones tell Rolland about the whale's general condition, its reproductive state—mature? pregnant? lactating?—levels of stress, and presence of parasites.
Despite its low numbers, the North Atlantic right whale may not be the rarest of all the great whales. There may be no more than a few hundred North Pacific right whales, Eubalaena japonica, which were harpooned illegally by Soviet whalers as late as the 1960s. But on the other side of the Equator, the southern right whale, Eubalaena australis, has rebounded from a few hundred in the 19th century to at least 10,000. If its cousins along North America's East Coast are the urban whales, these giants of the Southern Hemisphere are the wild whales, and they offer a vision of what a safer future might be like for the other two right whale species.
After feeding in plankton-laden waters around Antarctica, the various populations of E. australis migrate to wintering areas near Argentina, southern Africa, western and southern Australia, and sub-Antarctic New Zealand. The species has been increasing at a rate of up to 7 percent annually. That's close to the maximum possible for whales that require a full year for pregnancy, devote at least one more to nursing, and another to fatten up, and therefore can produce an offspring only every third year.
In July 2007 Rolland, Kraus, and I joined a team bound for the Auckland Islands, 300 miles south of New Zealand through some of the planet's stormiest latitudes, to carry out census and DNA work. As our 82-foot sailboat Evohe slipped into a protected bay amid the isles, there was nothing but sunshine washing the deck. Then, like explorers of a bygone era, we watched natives paddle across the water to surround our vessel. Except these natives paddled with flukes and blew spray from their heads.
Curious right whales investigated Evohe for hours while yellow-eyed penguins leaped along like skipping stones beside them. Great breaths overrode the sounds of waves and seabird cries and the mewling of young New Zealand sea lions from rookeries ashore. More whales milled and breached for as far as we could see. They were bigger than northern rights. More than one in ten were pinto-patterned, flashing yards of smooth white skin. A bygone era? This was beginning to feel more like the dawn of creation. Rolland and Krause, who had never viewed a southern right before, were beside themselves.
"Omigod. That one right there is the fattest young whale I have ever seen." (When judging the condition of northern rights, the scientists pay special attention to the area just behind the blowhole, where the chubbier animals develop a bulge of blubber. Its size has proved to be an accurate predictor of survival.) "We don't even have a category for a whale with a fat roll that big."
They're so clean! Not a mark on them."
Over the next three weeks, hundreds arrived in succession to give birth and nurse pale-colored infants or churn the water in SAGs and compete for mates before heading back to the open sea. Gales blew from all directions—this was midwinter in the Southern Hemisphere—coating the hillsides with snow. Researchers beat through the waves in a skiff to take identification photos and collect skin samples with small, hollow-tipped darts so they could define the genetic makeup of this recovering population more closely. Glenn Dunshea, from Australia's Center for Applied Marine Mammal Science, was interested in telomeres—DNA sequences at the tips of chromosomes that gradually shorten throughout an animal's life. By studying them in right whales, which may live at least the better part of a century (their close cousins, bowheads, may reach two), he hopes to discover more about telomeres' role in the aging process. Wouldn't it be humbling if a map to the legendary fountain of youth lay hidden within creatures we almost exterminated?
Kraus and Rolland roamed in a second skiff to view and photograph the whales in order to conduct detailed visual health evaluations, which they could compare with those of troubled whale populations back home. They wore their usual happy-to-be-in-the-kingdom-of-giants glow, yet it was mixed with a touch of sadness. As Rolland put it, "We just saw more right whale calves in two hours than people will see all year in the whole North Atlantic."
Safeguarding wildlife, even in the globe's most remote places, gets harder all the time.
The southern whales are doing fine for now, but keeping them that way will require better protection of critical wintering areas and migration routes. Fishing gear drowns so many diving seabirds in far southern waters that several kinds of albatrosses are in desperate trouble. As fisheries and whale populations both expand, conflicts with whales can't be far off.
As for the whales of the North Atlantic, commercial fishing and marine transport are huge, vital industries, and modifying their operations along the entire eastern seaboard to protect a few hundred giants won't be easy or cheap. Yet scientists' models say that saving just two sexually mature females each year from being killed would change the trend for this endangered species from either downward or level to upward.
Posed that way, the problem doesn't sound so hard to solve. A network of aerial and vessel surveys augmented by a force of volunteers who keep a sharp eye out for these warm-blooded submarines stands ready to help.
The volunteer force includes fast-striding beachcombers, folks who gather for morning coffee and then drive from one overlook to the next, and residents who watch from the windows of their condos. There are also the few, the proud … the vertical team. They take elevators to the tops of the tallest buildings around and scan the ocean from a seagull's perspective.
Still other whale trackers take to the air. Volunteer pilot George Terwilliger flew the scientists who saw mothers and calves in the Georgia Bight in 1984; before then no one knew where the last of the North Atlantic right whales went to give birth. Terwilliger still flies two to three times a week, piloting an Air Cam aircraft specially designed for low-speed reconnaissance and photography.
Whether a surfacing whale is spied from shore, roof, or sky, the information is quickly phoned in via hotline to the Early Warning System, which transmits it to military and commercial mariners. When operators of commercial vessels over 300 gross tons enter right whale habitats, they must notify a Mandatory Ship Reporting System, which automatically provides information about recent sightings.
It's far from a perfect strategy. Ship captains don't have to slow down if they don't feel like it. The federal government recently cut funding for right whale conservation research. But nothing seems to dampen the volunteers' enthusiasm.
Standing on the boardwalk of a gated community in Florida, binoculars at the ready, Donna McCutchan said, "Most people in this development were like me. They had no idea whales winter here. Now everybody knows about them, and they know to call in if they spot one." McCutchan herself hadn't seen a whale for weeks. She didn't mind waiting, she said. "I once got to watch a mother roll onto her back, and bottlenose dolphins started jumping over her. Whales are addictive. Once you see them, you don't want them to leave. Ever."
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