Fat Bear Week is back. And this year, it's all about the mamas

Bear 901 and her sole surviving cub are one of five brown bear families competing in this year's annual Fat Bear Week contest against 11 solo competitors. (C. Loberg/Fat Bear Week)Social SharingLISTEN | Interview with naturalist Mike Fitz:As It Happens6:21Mamas and their cubs join Fat Bear Week contest for 1st time For the first time, Fat Bear Week includes big, beautiful mommas and their big, beautiful babies.

The annual brackets-style contest, run by Alaska's Katmai National Park and Preserve, is a celebration of the park's beefiest brown bears, who gorge on salmon from the Brooks River in order to pack on as many pounds as possible ahead of their winter hibernation.

"This year, we saw more bear families at the river than ever before," Alaska naturalist Mike Fitz told As It Happens host Nil Kӧksal. 

"So this year we are featuring five mother bears and their cubs in Fat Bear Week to try to tell some of those stories, because the health and size of a cub is a direct reflection of a mother's effort."

Fat Bear Week competitor Bear 910 is the daughter of former champion, Beadnose. (C. Loberg/Fat Bear Week)Fat Bear Week started in 2014 and has since surged in popularity, inspiring similar initiatives, like Fat Marmot Week in Colorado. 

More than 1.7 million votes were cast last year and the team expects to exceed that number this year, says Fitz, a former Katmai National Park ranger who now works as the resident naturalist for Explore.org, which helps run the contest.

The contest features 16 bears or bear families facing off in a single-elimination, bracket-style tournament. 

And thanks to a particularly plentiful salmon run, the competition is fierce.  

The bear to beat is Chunk, a.k.a. Bear 32, a crowd favourite with several victories under his belt. He won last year's competition after reaching a whopping 1,200s pounds while nursing a broken jaw.

But Fitz says there are a few up-and-comers to watch this year, including Bear 151, a.k.a. Walker. 

"He's never won, but he's just a light bulb of a bear," Fitz said. "Every year, he just gets super pudgy. If I was to use another adjective for him, I would call him a pear-shaped."

When Backpack was an injured adolescent, rangers at Alaska's Katmai National Park and Preserve didn't think he would survive. Now he's fully grown and a major competitor in Fat Bear Week. (Explore.org)There's also Bear 89, a.k.a., Backpack, who survived a severe limp during his adolescence to become the brawny beast he is today. 

"He was the first bear that taught me how tough and resilient bears are, even at a young age," Fitz said. 

The fatter a bear gets during the summer and fall, the better their chance of surviving the long, cold winter. That's doubly important for females, says Fitz. 

"A mother bear goes into the den with fat reserves not only to survive that hibernation period for herself, but also for her cubs," he said.

A female bear may mate in early summer, but the fertilized embryos don't implant until she's hibernating in her den come November.

"If you don't go into the den with enough body fat reserves, then the mother is not going to give birth," he said. "So the fact that we saw so many cubs return to Brooks River this year means that a lot of female bears in 2025 went into the den healthy."

Bear 806 has two cubs, one of whom is adopted. Despite her generosity in taking in another bear's offspring, she also killed and partially ate a different bear cub this summer. (T. Carmack/Fat Bear Week)To celebrate that success, this year's bracket features five mother bears and their cubs. 

There's Bear 132 and her three cubs, one of whom became lost for several frantic days in June, only to be reunited with its family. 

There's also Bear 284, a.k.a. Electra, a mother of two who, according to her online bio, is known for her "curious and bold" personality, and Bear 610, described as "a small statured bear with a disproportionately large ability to overcome hardship."

Bear 806 is repping blended families with her biological cub and her adopted son, Biggie. Despite being generous enough to take in another bear's lost baby, she also killed and partially ate another bear cub in July who swam too close to her family.

Last, but not least, is Bear 901, who "readily achieves a level of fatness above that of many other bears," along with her sole surviving baby, one of the biggest cubs on the river.

Fitz says the Katmai bears' success is the product of Alaskans' dedication to protecting sockeye salmon, especially in the pristine waters of Bristol Bay, which is home to what he calls "one of the last great salmon runs on Earth."

But while Bristol Bay has seen record salmon runs over the last decade, he says the same is not true for all Alaska salmon. 

The bears of Katmai are successful because of an abundant salmon run in the region. (Guy Runco/Katmai Conservancy/The Associated Press)"Many are struggling, likely due to the effects of climate change and how it is impacting ocean food webs. Even though sockeye in Bristol Bay are doing well, we can't assume that will be the case in the future, especially if we continue to burn fossil fuels and force the climate to warm further or allow mining to happen," he said. 

"Fat Bear Week offers us an opportunity to see the benefits that large, healthy salmon runs bring to ecosystems."

Fat bear enthusiasts can vote online all week, and a winner will be declared Sept. 29.  

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