In a charming if mysterious twist of nature, sea otters play like puppies throughout their lives, failing to grow out of their childhood exuberance as most mammals do.
So it is with a touch of irony that three otters plucked from almost certain death after the Exxon Valdez oil spill in 1989 are celebrating their 10th anniversary at the Shedd Aquarium, cavorting for delighted audiences, even as their species is once again threatened by manmade events.
Plucked from the waters off the Alaskan coast, the otters arrived at the Shedd as bedraggled, orphaned infants. Eventually they were restored to health and have become unanticipated hits for the aquarium’s 1.5 million visitors, sometimes even stealing the show from the dolphins and beluga whales.
Yet their insatiable good cheer belies a little-known environmental drama playing out among the species as a whole that also could spell disaster for coastal ecosystems that rely on sea otters.
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Since 1990, killer whales–probably driven to hunger by humans overfishing Alaskan waters–uncharacteristically are attacking and devouring sea-otter populations to the point of extinction in some areas of Alaska.
With the otters gone, the seaweed-razing creatures they normally eat are left unchecked, the forests soon devoured and turned into lifeless underwater deserts.
The study of the otters at the Shedd has contributed to the overall record being accumulated on the species by scientists seeking to head off another environmental disaster.
Seeing the four sea otters in their Chicago habitat, it is hard to imagine that such ecological menace hangs in the balance of animals who live their lives so seemingly joyously.
“Otters play–romp around for no other reason than sheer enjoyment–throughout their lives, whereas most mammals stop play behaviors once they become adults,” said Ken Ramirez, chief marine mammal trainer at the Shedd.
“The otters are so full of fun and furry and cuddly to look at, it’s natural that they attract attention. When we offer classes on sea otters, they get a bigger turnout than the classes we offer on the dolphins and whales.”
It took one of the world’s earliest conservation efforts to save the species in 1910 after sea otters had been hunted to near extinction for their beautiful pelts. They dwindled to just 2,000 animals left along Pacific Rim coasts stretching from California to Japan.
The sea otters through this century built their numbers back to more than 200,000, but now manmade events again are threatening wild populations. The Exxon Valdez disaster killed at least 5,000 sea otters.
At the turn of this century the world learned how important sea otters are to coastal ecosystems when scientists were called in to investigate the disappearance of massive kelp (seaweed) beds off the coast of California.
Eventually, the scientists discovered the kelp forests disappeared because the sea otters disappeared. Otter fur, with up to 700,000 hairs to the square inch, is the densest in the animal kingdom and was so highly valued in the 18th and 19th centuries, hunters killed off nearly every wild sea otter colony in the world.
When the otters were exterminated, the kelp forests were left wide open to the animals the otters eat–bottom-dwelling, kelp-eating spiny sea urchins. Sea urchins soon stripped and ate all the kelp and other plants in the forest to the rocky sea bottom, leaving behind a desert devoid of all plant and animal life, including urchins.
In 1910, the U.S. passed a law protecting sea otters.
As sea otters have come back, so have the kelp forests. Kelp forests play an intrinsic role in life in the ocean, providing homes to such species as abalone, shrimp, lobster, crabs and clams. The forests are refuges for billions of small, juvenile fish to hide from predators and increase their chances of surviving to adulthood.
Thus, when the Exxon Valdez oil tanker ran aground in Prince William Sound in Alaska on March 24, 1989, and spilled 11 million gallons of crude oil into 1,300 miles of pristine shoreline waters, it was instantly recognized as one of history’s worst ecological disasters.
Thousands of oil and government workers, scientists, environmentalists and volunteers from all over the world were on the scene within days. Working to contain and clean up the spill, they rescued what they could of hundreds of thousands of wild animals coated by oil, from killer whales to harbor seals, bald eagles, loons, ducks and cormorants.
Because of the key role sea otters hold in the coastal chain of life, an elaborate triage center was set up specifically for them in the town of Valdez.
The oil proved fatal to many of the otters because of the way it matted their fur. They are the only marine mammals who have no layers of blubber to protect them from the cold ocean water, and if their thick coat of fur becomes matted, allowing the water to reach their skin, they die of hypothermia.
Among dozens of workers recruited for the otter rescue were four from the Shedd, including Ramirez.
“One of the devastating facts of the Exxon Valdez is the numbers of sea otters that died in the wild that we never knew about,” Ramirez said.
In all, rescue workers found about 5,400 stricken otters. Many were dead, many others had to be euthanized and the few that could be treated were cleaned and doctored for weeks and months. In the end, 5,000 died, 350 were brought back to health and eventually reintroduced to wild habitats.
Because the spill hit at the time of year sea otters give birth, about 50 tiny orphans were brought in. Baby otters cannot survive in the wild without their mothers caring for them and teaching them how to hunt, so the 50 were farmed out to be raised in zoos and aquariums.
Ramirez ended up taking back four babies, three females and a male.
“The male, Chenik, was in such bad shape when he arrived at the rescue center, everybody thought he was dead. He was revived with mouth-to-mouth resuscitation, but he was sickly and prone to seizures for the first three years of his life.”
At the Shedd, the babies grew quickly, and a year after they arrived, the federal government sent another newborn female, Kachemak, orphaned in a severe storm. As the otters grew, they seemed destined to become a breeding group until Chenik suddenly became ill again in 1997, when he died of heart failure.
The ladies, Kenai, Nuka, Nikishka and Kachemak, however, are doing swimmingly. They are so hyperactively playful it is hard to imagine that, now being 10 years old, they are entering into the geriatric years for otters.
In the wild, Ramirez said, few otters probably live 10 years, though they can live 15 to 18 years in captivity.
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“When they came here as babies, they had to be taught everything that their mothers in the wild would have taught them,” said Laura Monaco, the lead otter keeper at the Shedd.
That included teaching them how to use “tools” such as hard surfaces to crack open shellfish for their dinner. They used combs to show the babies how to fluff and condition their fur and hairdryers to show them how to blow insulating air into the fur.
“That’s one of the sounds we hear in the habitat–the animals blowing air into their coats,” Monaco said.
“We’re part of a captive breeding network,” Monaco said, “so at some point our girls will be involved in that.”
Captive-bred animals may be needed in the future to try to undo human mistakes by trying to reintroduce them in areas where wild otters have disappeared.
Scientists believe the whales have turned to eating otters because commercial fleets have overfished the area. As a result, animals dependent on the fish, especially seals and sea lions, have died off. That affects killer whales, whose prime diets are seals and sea lions.
“After Exxon-Valdez, we’re a lot better prepared now to deal with oil spills,” said Terrie Williams, a University of California Santa Cruz marine biologist. “But this is different, a shift in the ecosystem, with an oceanic predator coming in to eat sea otters along the coast.
“It’s going to take dramatic changes and tough decisions all along coasts, to get people to understand our demand for fish is going to have impact on marine mammals that we love.”