Oregon Zoo says goodbye to 19-year-old otter, Thelma: 'She beat the odds at every turn'

Sea otter Thelma plays in the Oregon Zoo's Steller Cove. ©Oregon Zoo/ photo by Shervin Hess

PORTLAND, Ore. - After a decline in health in her old age, a longstanding member of the Oregon Zoo’s family died over the weekend.

Thelma the sea otter was believed to be about 19 years old when she was humanely euthanized on Saturday.

She was rescued as a pup in 1998, and arrived at the Oregon Zoo with her companion Eddie in 2000.

Nicole Nicassio-Hiskey, the zoo’s senior marine life keeper, worked with Thelma for more than 15 years. She said Thelma “continually beat the odds” by surviving into her elderly years in spite of only having one lung.

“We knew she was getting up there in years and wouldn’t live forever, but it’s still hard to believe she’s gone,” said Nicassio-Hiskey. “She beat the odds at every turn. She was incredibly tough, but at the same time she had a really gentle and nurturing spirit.”

Zoos and aquariums take in so many orphaned sea otter pups that those in captivity are prevented from breeding. In spite of her birth control implants, Thelma gave birth to Ozzie - the first southern sea otter born and raised in captivity.

Nicassio-Hiskey said Thelma defied the odds again in 2006 when staff found that her left lung wasn’t inflating properly. Her best chance of survival was to have her lung removed.

“Remarkably, Thelma not only survived but thrived,” Nicassio-Hiskey said. “You would never have known it to look at her, but for the past 10 years she was swimming and diving and wrestling with Eddie all with just one lung.”

Thelma was named the Oregon Zoo’s Mother of the Year in 2015 after she adopted an orphaned otter pup, Juno.

“She was an amazing foster mom to Juno, probably because of the experience she had raising Oz,” Nicassio-Hiskey said. “They made a striking pair. Juno was much smaller than she is now, with rich brown fur over her entire body, whereas Thelma’s fur had turned white with age around her face and neck. Even though she was elderly for a sea otter, Thelma was still spry very energetic and playful.”

More information on sea otters from the Oregon Zoo:

Considered a keystone species, sea otters play critical role in the Pacific Coast marine ecosystem, promoting healthy kelp forests, which in turn support thousands of organisms.

Sea otters listed as threatened on the Endangered Species list once ranged along the north Pacific Rim from Japan to Baja California, including along the Oregon coast, and are thought to have numbered between 150,000 to 300,000 animals. Prized for their fur, the animals were hunted to the brink of extinction during the late 1800s and early 1900s. By 1911, aggressive fur-trapping campaigns had reduced the global sea otter population to around 2,000.

Although now protected against trapping, sea otters are threatened by oil spills, fishing nets and infectious diseases. Biologists estimate the population has dropped by 50 percent over the past 30 years. Wild sea otters have not established colonies off the Oregon coast since 1907, though a few individuals have been sighted, most recently in Depoe Bay in 2009.

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