How Many Salmon Do Bears Eat A Day?

How much fish can a bear consume? A lot! A huge and dominant male bear may occasionally catch and consume more than 30 fish per day on days when there are numerous salmon migrating in the river.

How much salmon can a bear consume?

On June 30, 2018, I observed 747, one of the biggest bears in the Brooks River, catch and consume 18 fish in just over three hours. Viewers of the bearcam saw him trap and eat numerous others earlier in the day. His catch that day can be conservatively judged to have been 30 salmon. 747 consumed 150 pounds (68 kg) of fish in a single day, assuming that each salmon weighed five pounds (2.3 kg). But is this typical? Over the course of a summer, how many fish do they consume?

At Brooks Falls, we frequently see bears participating in extended fishing trips, like 747 or 480 Otis. They spend hours sitting in the water, reeling in fish after fish. Their appetite seems to be unquenchable at this time. When fishing circumstances are ideal, adult bears at Brooks Falls can catch and consume dozens of salmon each day. A study from Kodiak Island can shed some light on the annual salmon consumption of Brooks River bears even if no study has attempted to quantify it.

Kodiak bears are very closely linked to bears on the Alaska Peninsula, especially Katmai, despite the fact that they are currently thought of as a subspecies of brown bear (Ursus arctos middendorffi). Like all brown bears, they shed their fur once every year in early to mid summer. Since new fur grows during the bears’ active season, it contains a record of what the bears ate at that time. Prior research on bears kept in captivity established a link between hair mercury concentration and mercury intake. Researchers first established how much mercury is present in the Pacific salmon that breed on Kodiak in order to apply this to bears in Kodiak. They next calculated the bears’ estimated salmon consumption by looking at the mercury content of their fur. The findings reveal that bears consume a lot of salmon, which is not surprising.

On Kodiak, adult male bears consumed an astounding 6,146 pounds (2,788 kg) of salmon annually on average, which is the most of any bear species. Female adults consumed 3,007 pounds (1,364 kg). Subadult bears, or autonomous young bears between 2.5 and 5.5 years old, differed in their consumption of salmon. Subadult males consumed 1,305 pounds (592 kilogram) of salmon annually, compared to 1,248 pounds (566 lb) for subadult females.

In Brooks Falls, bears don’t typically consume 150 pounds of salmon every day, as 747 did earlier this summer. A certain set of conditions—hungry bears, abundant salmon at Brooks Falls, and little rivalry from other bears for the best fishing spots—must coexist in order to achieve such a high consumption rate, and the catch rate is typically lower. However, based on the findings from Kodiak, bears on Katmai will easily eat thousands of pounds of fish over the summer and fall. Salmon is the primary food source for brown bears in both Katmai and Kodiak Island.

To survive, bears must consume six months’ worth of food or less. This fuels their almost insatiable need to capture and consume helpless prey. Their extreme hunger is demonstrated by the astounding quantity of fish they will consume.

The salmon capital of the summer is Brooks Falls.

About 2,200 brown bears reside in Katmai National Park, which boasts the greatest brown bear population in the world. Salmon, an abundant diet, is to thank for that density. Nearly 62 million sockeye salmon passed through Katmai National Park and the nearby Bristol Bay last year, according to the park. Because of this, these bears are some of the largest in the entire globe.

The bears must expend a lot of energy to stay alive during their latent period of hibernation; by the time they emerge from their dens in the spring, they may have lost up to one-third of their total weight, or even more if they are breastfeeding females. For brown bears to survive the lengthy winter hibernation, they effectively need to consume a year’s worth of food in just six months. Salmon makes up a sizable portion of the diets of the bears in Katmai, despite the fact that brown bears also eat berries, fruit, leaves, nuts, and roots. They consume up to 40 fish a day, or 100,000 calories and 100 pounds. The summer months are when these bears acquire 200 to 300 pounds, possibly reaching the 1,000-pound threshold.

The Brooks Falls bear cameras record the most activity between July and September. The Brooks River has a lot of fish in it during those months, but in August, the salmon in the area’s smaller streams tend to be more plentiful, so the bears follow the salmon there.

Mike Fitz recently emailed me and said, “I estimate that I’ve seen at least 35 to 40 different independent bears at Brooks River so far this summer, including at least 15 females with cubs. (A list of mothers and cubs spotted this year can be found on the Katmai Bearcams Wiki.)

Photos: Meet the Fish After Whole Foods Seafood Ban

Brown bears feast on the largest sockeye salmon run in the world at Brooks Falls. According to the website, brown bears may eat up to 40 fish every day, or up to 100 pounds. Because they tend to be full and asleep on days when fish are hopping, these coastal grizzly bears will also congregate during the salmon run when it is at its lowest point. The National Park Service produces a picture Katmai brown bear guide so you can know what you’re looking at (PDF).

Important adaptation: gluttony

A bear getting ready for hibernation has a greater desire to eat. A bear may not make it through the winter if it does not have enough fat reserves. It’s a lifesaver to be able to consume an abundance of food and turn it into fat. Grizzly bears in Alaska wait every year for the spawning salmon to return in their numbers at the end of the summer. They experience a physiological alteration known as hyperphagia, where they turn into eating machines. They will eat continuously for twenty hours, sleep for four hours, and then start eating again because their appetite is nearly insatiable in this state. Because there are so many salmon, bears frequently limit their diet to the fatty skin, brain, and eggs of the fish they consume. They have the capacity to ingest an astounding 100,000 calories each day, or 1282 cooked eggs.

How are they able to eat so much? What’s being served?

The bears go into a condition known as hyperphagia, a medical condition in which they constantly eat and can put on up to four pounds in a single day. Each sockeye salmon contains roughly 4,000 calories, so some bears can consume dozens of them per day.

Salmon, sedge grasses, and berries make up the majority of a coastal brown bear’s summertime diet. The fat in the salmon is what makes it possible to acquire so much weight so quickly. Once bears undergo hyperphagia in the late summer, they gain the majority of their weight then. The chemical leptin, which alerts the body when it is full, is inhibited, allowing the bears to eat until it is time for bed. 40 salmon were witnessed being consumed by one bear in one session. The bears engage in a procedure known as high grading at this time. They do this by removing the less fatty fillets and choosing to consume the sections of the fish that are highest in calories, such as the brain, skin, and roe.

Fish

If grizzly bears have access to a steady supply of fish, that will determine how much meat a brown bear consumes.

Brown bears consume spawning salmon for food. According to research, bears that have access to spawning fish may ingest up to 75% of their diet as fish. The amount of meat eaten may be less than 10% in the absence of spawning fish.

Up to 100 pounds of salmon have been observed being consumed daily by brown bears. This can equal as many as 40 salmon every day.

Brown bears in Alaska and British Columbia eat fish during the summer. Only the bears who live there will travel to dine on the salmon that are spawning.

Salmon migrate through the lakes and rivers of Brooks Falls in Alaska’s Katmai National Park in July. Given that it is one of the first streams that the pre-spawned salmon enter and that Brooks Falls acts as a natural barrier, fish provide a feast for the bears.

Grizzly bears mostly eat salmon, although they will consume other fish, including trout, if they are available.

The quantity of fish the bear consumes changes with the season. The bears will consume every portion of the fish at the beginning of the spawning season. Later in the season, they will just consume the sections that are the most fatty, ignoring the remainder.