Park rangers at Katmai National Park and Preserve spotted an unusually frail bear this summer.

It was late July, a time when the livestreamed fat bears typically devour copious amounts of fish. But this year, bear 480 — popularly known as Otis — looked like he hadn't eaten a good meal in months, Mike Fitz, a former Katmai park ranger and currently a resident naturalist for the bear cam livestreamers explore.org, told Mashable. Indeed, the salmon run was late, and clearly the aging bear Otis hadn't found success at his other fishing haunts.

"When he returned, I would consider his body to be emaciated," Fitz said. "We could see his ribs and hip bones."

SEE ALSO: Fat Bear Week is back. In 2023, the bears overcame big obstacles.

Might Otis, an animal over a quarter-of-a-century old and missing teeth, have awoken from hibernation too enfeebled to catch fish? This wouldn't be the first time rangers watched a frail or sick bear meet its demise at Katmai's famous Brooks River, a waterway that teems with salmon.

Yet Otis, as he's done time and time again, proved the doubters wrong.

"We could see his ribs and hipbones.

Otis employs a unique fishing style, staying profoundly stationary as he patiently stares into the river for passing salmon. Many other bears energetically dash for fish. This can make Otis appear passive or languid. But his technique has proven extremely effective. For around two decades, he's grown into one of the fattest Katmai bears, expelling little energy while consuming tens of thousands of calories a day.

And in 2023, a gaunt Otis lumbered over to his corner of the river, also known as "Otis' Office," and began waiting. And, soon enough, feasting.

"He immediately made up for lost time," Fitz said. "He must have been extraordinarily hungry."

As the images and footage below show, a month and a half later, Otis had amassed hundreds of pounds. Katmai chose him as a competitor in this year's Fat Bear Week contest, where he's a three-time champion.

Otis' 2023 transformation, from emaciated to filled-out. Credit: NPS / N. Boak / M. Whalen

"He just looks so much better, it's amazing," Naomi Boak, Katmai National Park and Preserve's media ranger, told Mashable. "He knows how to fish, that bear."

Fattening up is essential for bears like Otis. They hibernate from around November through April, and during this time subsist entirely on their fat stores. It's how they survive the harsh winter famine. More fat certainly doesn't guarantee survival. But it boosts a bear's chances of outlasting hibernation and awaking with enough energy to forage — and survive — in the unforgiving wilderness.

"He knows how to fish, that bear."

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Fat Bear Week is an opportunity to celebrate bears like Otis, animals persevering in a wild realm that, thanks to conservation, has been left largely untrammeled; it's an undeveloped region where lynx, bald eagles, salmon, wolverines, and bears abound. Regardless of the outcome of this year's contest, over the 2023 summer Otis proved he's a champion in his ursine world.

"Let's celebrate that survivor," Boak said.