Home
Donate Sign up for e-network
CENTER for BIOLOGICAL DIVERSITY Because life is good
ABOUT ACTION PROGRAMS SPECIES NEWSROOM PUBLICATIONS SUPPORT

Content on this page requires a newer version of Adobe Flash Player.

Get Adobe Flash player

WorldCatch News Network, November 7, 2000

Mystery: Why is the Aleutian ecosystem collapsing?

 

By Marla Cone, Los Angeles Times

There are few places on Earth that have changed so much, so fast as the narrow arc of islands where the Pacific Ocean greets the Bering Sea.

The Aleutian Islands are in the middle of nowhere. No tourists, no cruise ships, no chartered fishing trips, no quaint country inns. On a quiet day, when the turbulent seas and storied winds are still, you can hear a killer whale breathe.

But look and listen more closely. Something is missing.

Where are the sea lions, fat and happy, napping on the rocks and barking at their pups? And the furry sea otters crunching on urchins?

What became of the ample king crabs and shrimp, and the schools of silvery smelt? And where are the lush, undersea forests of kelp that provided food and refuge for fish?

As sudden and savage as an Arctic storm, some mysterious phenomenon has transformed this spectacular 1,300-mile archipelago in just a handful of years.

A vast sub-Arctic ecosystem is collapsing. No one knows why.

The sudden changes in the Gulf of Alaska and the Bering Sea have inspired an eclectic team of men and women to try to solve an extraordinary environmental whodunit. Virtually alone in a forbidding wilderness closer to Siberia than to Anchorage, they have been divebombed by eagles, bitten by otters, buffeted by 70-mph winds, rattled by earthquakes, and lost in storms. And each year they return for more, drawn back by the Aleutian paradox. If this rugged, remote ecosystem is collapsing, can any place on Earth be safe?

Jim Estes, a marine ecologist at the U.S. Geological Survey in Santa Cruz, Calif., has traveled to the Aleutians for the past 30 summers, studying what once was the world's largest and healthiest population of sea otters. Three summers ago Estes realized that the otters had virtually disappeared while he watched.

There were no bodies to dissect, few clues to decipher. The otters aren't starving. They aren't sick. They have vanished.

Throughout the Gulf of Alaska and probably the Bering Sea, too, the balance of prey and predator has been upended, a transformation so extreme it's called a "regime shift." Waters once brimming with seals, otters, and king crab are now dominated by sharks, pollock, and urchins.

Nearly no creature remains untouched.

"You just can't grasp how different things were 10 years ago," Estes said during a recent expedition. "No one has ever seen a decline of this magnitude in such a short period of time over such a large geographic area."

Piece by piece, over the last three years, scientists have started to solve the puzzle. Clues point toward something almost imperceptible that happened in the ocean in 1977. But the answers are more disturbing than satisfying, more elusive than conclusive. It seems the ocean's chain of life is actually a fragile silken web. If you remove a strand, the whole thing unravels. And it may never be whole again.

Tim Tinker is swathed in a bulky orange survival suit, hanging from the bow of a 25-foot boat as it hugs the rugged shore of Adak Island.

A brutal storm has just ended, leaving August skies crisp and clear.

Adak's mountains, set against a blue satin sky and fog as white as cotton balls, are draped with a luxuriant fleece blanket of moss. The green shines so brightly it seems as if it could glow in the dark.

Overhead, a bald eagle soars, and black and white puffins skim across the surface of the sea, their orange webbed feet splashing the 40-degree water.

From his perch on the bow, Tinker lifts his binoculars, training them on rocky reefs. For the ninth straight year, he is counting the Aleutians sea otters for an annual survey. He scans a reef and holds up a single finger clad in ragged wool gloves.

Iris Faraklas, a research assistant, dutifully makes a notationOne otter.

An hour into the survey, Tinker a marine mammal biologist at Santa Cruz and his colleague Brian Hatfield have counted only five otters and two harbor seals.

"Back in the old days, in the early '90s, we probably would have seen 500 otters by now," Estes said. "Now we go miles and miles without seeing even one."

This day, they will survey 200 miles of coast, finding only 171 adult otters and 29 pups.

If sea otters dream, they are surely dreaming about a place like Adak Island, in the middle of the Aleutian chain. There's plenty of food. Plenty of sanctuary. But only one otter per mile.

In the 1980s, as many as 100,000 otters inhabited the islands.

Today, only about 6,000 remain, according to aerial surveys. Between 1992 and 2000, the population dropped by 70 percent, a rate of decline that researchers say is unprecedented for any mammal population in the world.

"What's really horrifying is that the Aleutians have always been considered the stronghold of otter populations," said Rosa Meehan, who heads the marine mammal office of the U.S. Fish and Wildlife Service in Anchorage.

"At one time, 80 percent of the world's population of sea otters were out there," Meehan said.

Now, the wildlife agency has declared otters a candidate for endangered-species protection, although only in western Alaska.
In 1995, when they began to notice the signs of a population decline, Tinker and Estes, who specialize in otter behavior and population biology, at first looked for signs of disease, famine, or reproductive troubles. They found none.

For a couple of years, as the decline steepened, they were baffled.

If thousands of otters had died, where were the bodies?

Then it dawned on TinkerPerhaps the animals were being eaten. By killer whales.

Estes was disbelieving at first. For orcas, which are voracious predators, otters are little more than hairballs. Snack food for a killer whale.

Still, Estes remembered spotting an occasional killer whale lurking close to shore over the years. And it did seem odd that most of the surviving otters were in a small lagoon on Adak unreachable by killer whales. He decided to test the theory. In 1997, Estes and Tinker packed up a dead otter on Amchitka Island and flew it to California, where a colleague ground it up in a giant blender, calculated its calorie load, and compared it with how many calories a killer whale consumes.
It turned out that fewer than four whales, 3.7 to be exact, could have eaten 40,000 otters in five years.

"We were absolutely blown away," Estes said.

But orcas had lived in harmony with otters for thousands of years on the Aleutians. Why, all of a sudden, were they preying on them so heavily?

To find the answer, biologists simply had to follow the food chain.

Orcas customarily feed on sea lions and seals, which are packed with high-calorie blubber. But the population of Steller sea lions, the world's biggest sea lions, took a sharp dive in the late 1980s. Harbor seals also declined at a similar rate.

By 1992, otters were the only plentiful marine mammals left in Aleutian waters. The orcas, in their hunt for calories, apparently had been forced to switch prey.

The effects cascaded rapidly down the food chain.

With far fewer otters around to eat them, sea urchin populations exploded increasing eightfold within a few years. As many as 100 of the spiny green creatures now cover each square foot of ocean floor around the Aleutians.

The urchins, in turn, ate the kelp.

In 1993, kelp forests were 20 feet deep and so thick they clogged the engines of Brenda Konar's dive boat. "Now the only kelp you find is the stuff right by the shoreline, and it's maybe only three feet deep," said Konar, a biologist with the School of Fisheries and Ocean Sciences in Fairbanks.

When the leafy undersea forests vanished, so did many of the rockfish, snails, starfish, and other creatures that use the kelp for food, shelter, and breeding grounds. Some local seabirds, mainly puffins and kittiwakes, also are hurting from lack of fish.

The Aleutians offer proof that one small ecological change can move like a tsunami throughout the entire ocean realm.

Yet the snarl in the food web had to begin somewhere. Where, scientists wondered. And, even more important, who or what did it?

The Aleutians are a dynamic place, ever-changing. Fog shrouds the islands one instant and retreats the next. Hurricane-force squalls descend with little warning. The environment of the Aleutians, however, isn't supposed to be as capricious as its weather. Ecosystems normally evolve slowly.

"I have not come across any other example of such a total flip- flop," of an ocean environment, said Bruce Wright, a division chief at the National Marine Fisheries Service in Alaska.

Ecological shifts as sudden and sweeping as the ones in the Aleutians usually can come only from human interference, said David Lindberg, an evolutionary biologist at the University of California, Berkeley. If the shift were natural, animals and plants of the Aleutians would have evolved with some defensive strategies, he said.

"We're incredible, as a species, at speeding up changes," Lindberg said.

Scientists are exploring many factors global warming, overfishing, pollution that might have played a role in the Aleutians misfortunes.
Looking back, they theorize that the key event may have come in 1977, when a sudden warming just two degrees Celsius in the average temperature of the Gulf of Alaska was recorded.

The Arctic has been especially vulnerable to climate change, which many scientists believe is caused in part by worldwide burning of fossil fuels and production of greenhouse gases.
Though they cannot know for sure, researchers believe the chain of events was most likely this: Warmer water caused plankton short-lived and ultra-sensitive to temperature changes to disappear. Tiny copepods and krill probably followed quickly.

The shrimp and crab, along with smelt fishes such as capelin and herring, would have vanished afterward, deprived of their food, to be replaced by an explosion of cod and pollock. Once-thriving shrimp and crab fisheries collapsed in the late 1970s while the new species attracted large fishing trawlers that descended on Alaska, harvesting millions of tons of pollock and cod a year for American and Japanese consumers.

By the mid-1980s, the problems spread to young mammals.

The decline of the smelt fishes probably triggered the collapse of the seal and sea lion populations, say marine mammal biologists, including Kathy Frost of the Alaska Department of Fish and Game. The smelt are high in fat, and without them, baby mammals might not find enough calories to survive the winters.

But salmon like warmer water. Their populations have increased, drawing sharks, which feed on salmon and at times on seals and sea lions.

All of a sudden, the Aleutians had turned into a predator pit, unsafe for marine mammals.

So far, the rest of Alaska has escaped the regime shift, presumably because waters elsewhere around the state have different ocean circulation patterns and have not warmed.

Commercial fishing of pollock and cod may be exacerbating the food shortage for the mammals. In July, a federal judge ordered the U.S. government to ban commercial fishing around the Aleutians to protect endangered sea lions. Before the ban, nearly every fish filet sold at U.S. fast-food outlets had come from Aleutian waters.

Commercial fishermen in Alaska say it is unfair to blame them.
Pollock are still plentiful and they had never harvested the capelin and other smelt important to sea lions. But environmentalists argue that the huge trawling operations are now taking the only food left for the animals.

The Aleutians are so unpredictable that scientists may never be able to unravel all the biological interactions and prove or disprove their theories about how the food web got tangled.

"It drives people crazy when you don't give them a straight answer," said Frost of the state wildlife agency. "But it's an unbelievably complicated place, and biology is not a very clean science.

Animals are like people. There is never one factor at play. . . .

Sometimes you poke along and poke along and all of a sudden, the pieces fall into place."

Some experts say the ocean may be shifting back, favoring the marine mammals again instead of the sharks and pollock. If it does, Estes and his team will be there to chronicle it.

But even if all the elements the forage fish, the otters, the sea lions, the kelp were to return, these islands will never be the same.

Like marble chips in a kaleidoscope, they would fall in different patterns.

"I'm not going to see it recover in my lifetime," Estes said.

Photo courtesy of USFWS