Lake trout cull could boost cutthroat, feed grizzlies

Grizzly and black bears that once feasted on cutthroat trout spawning in Yellowstone Lake tributaries will readily return to the food source if the species bounces back, a study predicts. The study, “Contrasting Past and Current Number of Bears Visiting Yellowstone Cutthroat Trout Streams,” supports a multimillion-dollar effort to reduce invasive mackinaw in Yellowstone Lake. The paper was published in the Journal of Wildlife Management in February. “We suggest that the number of spawning trout per stream will have to reach approximately 400 fish per kilometer of stream before large numbers of grizzly and black bears once again specialize on this food,” Washington State University researcher and chief author Justin Teisberg wrote. “If the Yellowstone Lake cutthroat trout population can be recovered to such levels,” Teisberg wrote, “grizzly and black bears that still reside within the lake basin will readily find and use this high-quality food resource, potentially returning both species to higher use of backcountry habitat.” Teisberg, who conducted field work from 2007 to 2010, suggests that cutthroat numbers have a long way to go before the species is a dependable food source for bruins once again. A similar survey of spawning activity and grizzly bear use was conducted between 1997 and 2000, providing Teisberg with comparable data...more