Wednesday, September 15, 2010

What’s causing a massive walrus haulout in northwest Alaska?

Look to the north from a seaside street in the small village of Point Lay, Alaska and you'll witness a phenomenon that has locals and scientists alike awestruck: A few miles down the coastline, tens of thousands of walruses are jammed together in a tight beach-bound pod to catch a little R&R from their daily routine.
This is not a small group -- we're talking in the neighborhood of 40 million collective pounds of massive marine mammal.
"You can see them right now," said Leo Ferreira, the village's mayor, late Friday afternoon. "I am on the main road facing the ocean, I am right by the church and I can see them right here and they are about two miles away."

Walrus high on the barrier Island beaches (USGS photo)

Ferreira theorizes that ship traffic is diverting the walruses to shore in unusual increasing numbers. But government scientists suspect it has more to do with an increasing lack of sea ice. Walruses have been known to haul out onto land in large numbers in Russia, but never on the Alaska side of their migratory corridor in the tens of thousands, as is being witnessed this year.
Walrus researchers with the United States Geological Survey estimate there could be anywhere from 10,000 to 20,000 of the mammals currently taking a rest along Alaska's Chukchi coastline. Ferreira, one of about 234 people who call Point Lay home, thinks the numbers may be even higher. Since only about 20 percent of walruses generally come to shore, scientists suspect another 80,000 walruses may be swimming nearby.
In 2007 and 2009, large number of walruses parked themselves on Alaska beaches in clusters as large as 600 to 800 each. Last year near Icy Cape, a trampling event led to the deaths of more than 100 of the animals, most of whom were juveniles crushed as the group headed for water en masse, likely after getting spooked. By what remains unknown.
Steps are being taken to try to make sure that doesn't happen with the group hauled out in Point Lay. Flight restrictions have been imposed, and the village is refusing to indulge out of town tourists who are shopping around for boat rides to get a closer look. Hunters have been asked to stay away from the main group, and people seem to be respecting that request, according to Ferreira.
USGS scientists traveled to Point Lay earlier this month to tag some of the walruses in an effort to track and study their movement. They're particularly interested in how much more swimming the hauled out walruses, most of which are females, will have to do to find food and how that extra effort will affect the animals' health. They're also worried about how young walruses -- which rely on a mother's care for two years and which nurse for the first six to seven months of life -- will fare.
"We suspect it will have real change in the cost of making a living for the walrus. Instead of rolling off the ice and having your food right there, they might have to commute," said Tony Fischbach, a USGS walrus researcher who just returned from the field trip to Point Lay.
Walruses use sea ice to travel a shallow-water food corridor between Russia and Alaska, feeding on clams, worms and other creatures from the sea floor, heading to the ice every day or so for a rest. Scientists don't know what walrus endurance is like in the water without a break, but suspect it tops out at about 10 days. Their dense, heavy body weight -- which can reach two to three tons for mature adults -- makes them relatively inefficient in the water compared to other marine mammals, according to Dan Monson, who is also with the USGS's walrus research project.
Males may be more adaptable, thanks to a built-in ability to hang out longer than females in ice-free waters thanks to air-trapping throat patches that help keep them afloat. It allows them to rest with a "big wad of air in their cheeks, but females and calves do not have that ability," Monson explained.
For scientists, the health of the females and their young is especially worrisome. Females need to be healthy enough to reproduce and care for their young, and the young must be able to withstand the additional hardships a more ice-free existence may pose. Without ice as a landmark to help find their calves, mothers may have a more difficult time locating their young after a trip away in search of food, while the very young are likely to struggle the most with long swims to the coast and are the most vulnerable to trampling once on land.

Studying a day in the life of a walrus

To answer the unknowns, scientists have begun tracking the Pacific walruses. They want to know how much time they spend on ice, swimming, resting and foraging.
They use specialized mountain bikes designed for snow and ice to travel the coastline on scouting missions. And to attach the transmitters, they must take a cue out of the playbook of a biathlete.
Placing a radio collar on a walrus, as is done with polar bears and other animals, isn't an option. You can't fly over armed with a dart gun, as the group may get scared and head toward sea, causing unnecessary deaths as the large animals squish and scramble over one another. Plus, attempting to tranquilize a mammal the size of a small car as it's in or near water doesn't work. Walrus researchers are instead forced to gingerly slide up to the pods on their bellies, armed with a crossbow, and launch a high-tech dart into the skin on the mammal's back.
"We just place it on their back with a small anchor that embeds underneath their skin," Fischbach explained. "For a walrus it's just a splinter on their back."
Fischbach and his colleagues began tagging walruses in June. Through data collected over the two months each transmitter remains attached, they hope to learn more about the day in the life of the walruses as they make their journey from spring to winter, at first with the ice and then ice-free as the season progresses.
Federal officials are currently reviewing whether the Pacific Walrus and its habitat should be protected under the Endangered Species Act. The Center for Biological Diversity sued to get the walrus listed, and believes that without intervention, the iconic animal will be a "trajectory toward extinction" by the end of the century. The government has until the end of January 2011 to make its decision, and has recently released the results of two studies -- one on Arctic sea ice decline, and another on the state of Pacific walrus in the 21st century -- that will contribute to its finding.

In a changing Arctic, what is 'normal'?

In Point Lay the walruses, which are hauled out on barrier island on the other side of lagoon that separates the village from the ocean, are hard to miss, and if the rolling pounds of muscle don't catch your eye, the sound will.
"On a quiet morning you can hear them. Everybody hears them," Ferreira said just before mimicking the vocalizations researcher Tony Fischbach aptly describes as "a cacophony of low sounds, grunting and whistling -- low range barking -- like a really big dog yard where the dogs have very deep voices."
Local hunters are enjoying this fall's walrus phenomenon -- they're able to get their kill without traveling too far. But village leaders are worried carcasses left too close to town will bring a bad omen: polar bears. A starving polar bear killed a 28-year-old man in Point Lay in 1990 -- an event that very much remains in the community's consciousness. In addition to not disturbing the main pods, hunters have been asked to stay at least five miles away from the village.
Point Lay fire chief Bill Tracey Sr. is among the locals who, like Ferreira and the village council, feels protective of the massive walrus marvel that descended in force a week or so ago. Bush pilots have been warned to stay away, and he isn't shy about shutting down the hopes of would-be tourists looking for a way to get their own up close and personal experience with the mammals.
Although he's deterring visitors, Tracey is one of the few people to have been fortunate enough to witness the event firsthand. Early one morning he and his wife quietly made their way to the beach in a boat, cutting the engines when they could hear walruses both ahead and behind them. They pulled ashore, and moving slowly and sometimes on their bellies, worked their way into the thick of it. Lying on a small hill overlooking the pod, he brushed enough grass aside to slide his camera lens forward and captured his own series of stunning images.
"I've lived here 37 years and I've never seen anything like it," he said. "It was just walruses being walruses. They weren't scared. They were just laying there poking each other once in a while and showing a lot of ivory."
Whether it will remain a once-in-a-lifetime event remains to be seen. Scientists don't yet know what "normal" is for the walruses in a changing Arctic. They're seeking out data, and also taking it in as it comes their way, as with the tens of thousands of walruses that have chosen Point Lay as a current pit stop.
"Walruses like to be very close to each other. They are on top of each other. They're very social so there's a lot of jostling," Fischbach said. "It's pretty amazing. It's a very noisy hubbub."
Contact Jill Burke at jill(at) .

No comments:

Post a Comment