A decline in native fish in Yellowstone National Park is causing the region’s grizzly bears to turn to a new source of food: Baby elk.
Since the 1980s, more than 90 percent of native cutthroat trout in the park have died off, according to the Greater Yellowstone Coalition:
“Since the illegal introduction of lake trout in the 1980s, the cutthroat population in Yellowstone Lake has plummeted. Catch rates for Yellowstone cutthroats have significantly dropped as more and more lake trout are caught every year. The precipitous drop in cutthroat numbers is a result of lake trout predating on cutthroat trout.”
A new study, published in the Proceedings of the Royal Society: Biological Studies, links the decline of fish to the change in grizzly bears’ predation habits. After crunching the numbers, researchers saw that these shifts have caused a 2-11 percent decrease in elk population growth.
“In the late 1980s, grizzly and black bears killed an estimated 12 per cent of the elk calves in northern Yellowstone annually,” the researchers wrote. “By the mid-2000s, bears were estimated to kill 41 per cent of calves.”
The study is an excellent reminder of the lasting and major impact that humans can have on the natural environment, as well as the importance of following rules and regulations within national parks. Researchers believe the shift in Yellowstone “could permanently alter native species interactions.”
For more information about how to visit America’s national parks in a safe and sustainable way, visit the National Park Service website.