Invasive lake trout population declines in Yellowstone

CODY, Wyo. (AP) - Yellowstone cutthroat trout could finally make a recovery in Yellowstone Lake after data showed an invasive lake trout species has declined, experts said.

"Nowhere else has seen the kind of adult lake trout collapse at the rate that has been achieved on Yellowstone Lake, not on the Great Lakes, not on Lake Pend Oreille (in Idaho)," retired biologist Michael Hansen told The Cody Enterprise.

Hansen formerly worked for the Great Lakes Science Center of the U.S. Geological Survey and was a longtime member of the Science Review Panel for the fisheries of Yellowstone National Park.

"It was hard to contain my excitement," said Dave Sweet, special project manager for Wyoming Trout! Unlimited. "I have been working on Yellowstone Lake for 12 years volunteering on the system, fundraising and trying to spread the word about what was happening."

Intensive netting efforts have reduced adult lake trout to 10%, or about 10,000, he said. About 60,000 lived in the lake 10 years ago and were known to prey on cutthroats.

"Literally for years, we thought we were losing the battle," Sweet said.

A sexually mature lake trout starts laying eggs at age 5-6 and can live as long as 50 years, while cutthroat, a native species to the lake, only live up to 5 years, he said.

There are still about 450,000 juvenile lake trout that are about 2 years old and under, but they are not expected to last, experts said.

The National Park Service spends about $2 million each year on netting.

"This resource is at the top of my list for continued funding in these times of tightening budgets and uncertainty caused by the coronavirus," Yellowstone Nati! onal Park Superintendent Cam Sholly said.