Death of oldest otter highlights Tennessee Aquarium’s efforts to adapt to needs of aging animals

Contributed photo / Delmar the North American River Otter lounges in the Tennessee Aquarium's River Otter Falls exhibit.
Contributed photo / Delmar the North American River Otter lounges in the Tennessee Aquarium's River Otter Falls exhibit.

Last month the Tennessee Aquarium's River Otter Falls exhibit lost its longest tenured resident, Delmar.

At 18 years of age, Delmar had long surpassed the 12-year median lifespan of a North American river otter, said Senior Animal Care Specialist Jennifer Wawra, who serves as the primary caretaker for the River Otter Falls exhibit.

Animals at zoos and aquariums are living longer than ever, requiring their caretakers to adapt and sometimes make tough decisions as their health declines.

"That's actually kind of a big thing within zoos and aquariums overall right now," Wawra said by phone. "These animals are living so much longer, and now we're dealing with things we've never had to deal with before."

Animals in captivity don't have many of the problems they encounter in the wild, such as predators or a lack of access to nutritious foods, she said.

Like humans, animals' health declines as they age. But with humans, we generally know what we can expect to happen to our bodies at certain ages.

"We don't really know that for animals because we haven't had this level of care and this level of monitoring," Wawra said. "So we're really getting to learn a lot and record a lot of data, which has been really interesting."

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As he aged, Delmar had developed severe arthritis in his hips and knees that affected his movement. He also had a herniated disk in his back.

Aquarium staff treated his arthritis with regenerative cold laser therapy, a suggestion received from peers at one of the many zoos and aquariums across the U.S. and Canada that Tennessee Aquarium staff contacted about potential treatments for Delmar.

Delmar's keepers adapted his training regimen to accommodate his less-agile body and selected enrichment items fitting his abilities and preferences.

  photo  Contributed photo/ Delmar the North American River Otter enjoys an enrichment snow day.

"We wanted him to be able to still engage with everything and have something to get up for every day," she said.

They started paying more attention to which otters they would put into the display with Delmar, in an effort to prevent the very active otters from playing too rough with him and putting stress on his arthritic joints.

Delmar was having difficulty navigating the large concrete "boulders" in the otter habitat, so maintenance staff built a ramp from plywood and fire hose donated by local departments to make it more accessible, she said.

"We are also developing quality of life scales, which is not something I've ever really worked with in my career," said Wawra, who worked with the team that cares for the aquarium's lemurs, several of which are older animals, and the aquarium's veterinary staff to develop a quality of life scale for Delmar.

In the year before his death, Wawra monitored Delmar's behavior and rated his quality of life on a daily basis using a scale of 1 to 4, with 4 being normal behavior.

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In January, keepers saw a significant change in behavior. When he went to the veterinarian for a physical, it was discovered that his health problems reached beyond just the arthritis and herniated disk in his back.

Wawra and veterinary staff had to make the difficult decision to euthanize Delmar.

"Delmar lived a very good, very long life, but it was very challenging to kind of weigh the good and the bad, what we expected from him, what he expected from us," Wawra said. "It was a very, very hard day."

The temporary ramp built for Delmar is still in the exhibit, as it benefits all the otters.

"All of our animals are aging," Wawra said, adding that the aquarium plans to build a permanent ramp system for the exhibit by this summer.

After seeing the benefits of cold laser therapy with Delmar as well as an older lemur and several of the older turtles and penguins that received the same treatment, the aquarium is purchasing a cold laser to help all the animals "age more gracefully" that will arrive later this year, Wawra said.

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The aquarium has several animals living beyond the median lifespan for their species, aquarium spokesman Thom Benson said by email.

One of the aquarium's sand tiger sharks is estimated to be 30 years old, well beyond the species' median life expectancy of 21.4 years. An 11-year-old ocellated river ray and a 16-year-old white-blotched river ray have far surpassed their median life expectancies of about 6 years, he said.

At 35, a Barbour's map turtle has aged 15 years beyond the species' median life expectancy, and a 26-year-old female ringed map turtle is more than double the median life expectancy of 12 years for females of that species, Benson said.

Just as Wawra sought advice from peers at other zoos and aquariums about treatment for Delmar, she and her colleagues are teaching the next generation of keepers what signs to look for when evaluating their animals' behavior to determine their quality of life and adapt their care as they age, she said.

Contact Emily Crisman at or 423-757-6508.

  photo  Contributed photo / Two of the Aquarium's North American River Otters use a ramp that was installed to make it easier to climb to the top of their exhibit.

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