When you think about salmon in Alaska, you might picture grizzly bears standing in a gushing stream and snapping up spawning fish as they leap against the current. (Even a Steamfresh® Chef’s Favorites frozen dinner commercial plays off this image, as does this John West Red Salmon clip).
But for all the iconic footage of salmon runs, this annual rite of passage and predation has gone largely unstudied from the point of view of individual bears—especially outside of easily observable areas.
The challenge is that observations of bears are generally too few and too close to reveal natural feeding behavior, so most of what we know about the bear-salmon relationship comes from fish carcass surveys: We see what’s been eaten, but not always who did the eating, or how often or where or when. That leaves a lot of unknowns, including how many bears hunt along salmon spawning-streams, and whether bears return to the same stream year after year.
To answer these questions and others, two units in the College of the Environment—the School of Aquatic and Fishery Sciences (SAFS) and the School of Environmental and Forest Sciences (SEFS)—have launched a coordinated research project.
Led by SAFS Professor Tom Quinn and SEFS Professor Aaron Wirsing, this new study is investigating coastal brown bear (Ursus arctos) abundance and behavior along sockeye salmon (Oncorhynchus nerka) spawning streams in Bristol Bay, Alaska. Their project draws from decades of existing salmon research and introduces a completely new perspective by exploring individual brown bear behavior, including monitoring bears through remote cameras and collecting hair samples for DNA analysis.
The research team is housed at the Fisheries Research Institute, a program within SAFS, and based in the village of Aleknagik. In addition to Professors Quinn and Wirsing, the crew includes SAFS graduate student Curry Cunningham and Professor Lisette Waits from the University of Idaho.
Their work began in 2010 by placing the first cameras along salmon-spawning streams in the Wood River Lakes System. In July 2012, they then deployed barbed wire across three streams to begin snagging tufts of hair from foraging bears. This past summer, they expanded the research area and deployed two barbed wires each on six streams. One wire per stream is paired with a remote camera trap to document what happens when bears encounter the wires. The wires are set just high enough—55-60 centimeters—for bears to step gingerly over them, often leaving small tufts of hair behind (when good samples are collected, they call it a “good hair day”). The hairs, in turn, yield DNA samples that help researchers identify individual bears.
The study is designed to be noninvasive, so among the questions to answer was whether the wires would impact or otherwise disrupt bear behavior and hunting. Judging from the camera images so far—including many taken at night (see slideshow below)—the bears appear largely unconcerned with the wires, often stepping over and under multiple times in a single encounter (in the process, of course, leaving collectible tufts of hair).
In the first year of hair sampling last summer, the team collected 74 tufts from wires along Bear, Happy, and Hansen creeks. They have analyzed 41 of the samples so far and have successfully identified 15 different individuals—eleven females, four males, and all brown bears.
Field work is just winding down for this summer (at left, check out a slideshow of photos Professor Wirsing took a few weeks ago). They plan to continue the project for a few more years, and as researchers sort through several hundred new samples to analyze, they’re excited to open this window into a largely unseen and unstudied realm of bear behavior.
“Outside of a few highly visible areas, such as the McNeil River, the behavior of brown bears foraging on salmon has been largely shrouded in mystery,” says Wirsing. “We hope our work will reveal how feeding and social behavior of individual bears are shaped by the arrival of migrating salmon—and by extension how coastal brown bear populations might be affected by changes to the size and timing of salmon runs.”
In the short video clip below, Professor Wirsing captures sockeye salmon swimming up Hansen Creek, which in some places is only a couple inches deep as it approaches Lake Aleknagik. You’ll get a glimpse—a tiny glimpse, mind you—of the herculean effort it takes for salmon to reach their spawning grounds. Their exertion is nothing short of heroic during this brutal slog. After all, even when they manage to dodge the maw of a hungry grizzly, they still have to muscle their way through narrow, shallow streams to reach their final destinations. In some cases, a few of the larger males get too fatigued to maneuver through the shallowest sections and end up stranded. Those beached souls then sometimes have to suffer through gulls pecking their eyes out as a final insult. No question, it’s an unforgiving business.
Slideshow photos, hair tuft and salmon video © Aaron Wirsing; all other photos © Tom Quinn.