Katmai National Park’s annual Fat Bear Week is underway again: A time when the general public watches livestreams of feeding and fighting brown bears at Brooks Falls in southwest Alaska. Though it’s a shameless publicity stunt (which includes bracket-style voting for bears, many of which have names), it’s an effective one. Fat Bear Week is ultimately educating the public about brown bears. This time of year, these apex predators are packing on the pounds by feasting on calorie-rich sockeye salmon at Brooks Falls. All that fat is crucial for helping bears survive the harsh Alaskan winter. Bears do not truly hibernate, but instead enervate, or enter a state of torpor, in their dens. A bear’s metabolic rate drops while they’re in the den, and the bears survive off their fat stores.
A bear can lose up to one-third of its body weight in the den, which is why their fat stores are crucial. According to the NPS, “in the Brooks River area of Katmai National Park, bears gorge on summer’s bounty in their attempt to eat a winter’s worth of food in about six months. Large bears can gain a few hundred pounds in fat before they retire to their winter dens.”
The winner of the 2018 Fat Bear Week was bear 409, a sow that fished Brooks falls for two-plus decades. Brown bears can steadily gain 1 to 2 pounds per day during summer foraging. Photo by A. Ramos / Katmai NPSThe 2019 champ, a sow known as bear 435. A successful female brown bear can give birth to four or more litters of cubs throughout her lifetime, according to the NPS. It’s easier for sows to pack on the pre-winter pounds in years when they don’t have cubs, with whom they share food. Photo courtesy Lance B. Carter / Katmai NPSA big boar known as bear 747 pictured at Brooks Falls in 2020, when he first won Fat Bear Week. On days when many salmon are migrating, a large and dominant male bear like 747 will sometimes catch and eat more than 30 fish per day. Photo by N. Boak / Katmai NThe 2021 champ, a boar known as 480, fished Brooks Falls for more than 20 years. One sockeye salmon contains about 4,500 calories, but the fattiest parts of the fish contain the most calories. When fish are abundant, brown bears tend to selectively eat the fattiest parts — skin, brain, and eggs — and leave the rest. When fish are less abundant, they’ll eat the whole thing. Photo courtesy Lian Law / Katmai NPSBear 747 is one of the biggest brown bears you’ll ever see. Here he’s pictured at Brooks Falls in 2022, when he won Fat Bear Week for a second time. Photo courtesy Lian Law / Katmai NPSBear 747, which resembles an oversized Labrador retriever more than anything here, can weigh an estimated 1,400 pounds in the fall. Photo courtesy Lian Law / Katmai NPSThe 2023 (and 2024) Fat Bear Week champ was a sow identified as Bear 128. She’s raised several litters of cubs, with whom she shares salmon. In Katmai, cubs generally stay with their mothers for 2.5 years and separate in May or June of a cub’s third summer. Some sows, however, keep their cubs through a third summer before running them off the following spring. Photo by F. Jimenez / Katmai NPSBear 128 was also crowned champ in 2024, after one of her cubs was killed by a boar. (She’s photographed here in Sept. 2022, at a much heavier weight.) Photo by Lian Law / Katmai NPS
The 2025 winner remains uncrowned, but you can watch live streams of the bears fishing at Brooks Falls below. You can also check out more stories about bears here:
