Broad impacts from lake trout invasion in Yellowstone

Date:  March 20, 2019

Source:  University of Wyoming

     

Introduction of nonnative lake trout in Yellowstone Lake has affected organisms from the microscopic level in the lake to large animals in the region, according to newly published research.

Zooplankton, cutthroat trout, river otters, osprey, bald eagles, bears and likely elk are among the creatures whose numbers, diet and behavior have been altered as a result of the presence of the invasive fish, says an article that appears today in the scientific journal Science Advances.

The authors include Lusha Tronstad, research scientist with the Wyoming Natural Diversity Database at the University of Wyoming; National Park Service scientists Todd Koel, Jeffrey Arnold, Kerry Gunther, Doug Smith and Patrick White; and John Syslo of the Montana Cooperative Fishery Research Unit at Montana State University.

The scientists analyzed data spanning more than four decades, from 1972-2017, and concluded that the impact of lake trout in Yellowstone Lake -- in particular, the decline of native cutthroat trout -- has cascaded across the lake, its tributaries and the surrounding ecosystem.

"Our study illustrates the potential impact of a single, invasive predatory species on otherwise pristine ecosystems," the researchers wrote, providing further support for Yellowstone National Park's efforts to suppress the lake trout population in Yellowstone Lake.

Monitoring over the past three decades has shown a dramatic drop in the numbers of native cutthroat trout that inhabit Yellowstone Lake and spawn in its tributaries, largely as a result of the illegal introduction in the 1980s of lake trout -- which prey on cutthroats and spawn at depths inaccessible to bears, birds and other animals.

Continued