The ecological balance of the continent's largest high-elevation lake - the pristine jewel of Yellowstone National Park - is threatened by an invasion of alien trout.
And it seems to be no accident - the alien
trout were likely slipped into Yellowstone Lake by anglers seeking
to start a stock of catchable trophy fish. "An appalling act of
environmental vandalism," says departing Yellowstone Park
Superindent Bob Barbee.
The aliens are lake
trout, also known as Mackinaw trout, native to Canada and the Great
Because of their popularity with
anglers, over the years lake trout have been introduced into lakes
around the West, either officially by wildlife agencies, or
surreptitiously by anglers.
The practice fell
into ill repute as the repercussions became known: Lake trout are
so aggressive they often played havoc with local native fish. Lynn
Kaeding, project leader for the U.S. Fish and Wildlife Service in
Yellowstone, says lake trout wiped out a native species of
cutthroat trout in some high-country lakes in
Three other Yellowstone Park lakes -
Heart, Lewis and Shoshone - already have been contaminated with
But larger Yellowstone Lake, set amid
surrounding peaks at an elevation of 7,733 feet, has long remained
free of outside influences. Some 80 percent of the nation's
remaining Yellowstone cutthroats live in the lake and the rivers
and streams that drain into or out of it, making the lake "the
heart of the whole population," " Kaeding
There have been scattered reports for 30
years of exotic lake trout in Yellowstone Lake, but never any proof
until this summer, when anglers caught and turned in two of the
fish. Biologists have learned of at least four other lake trout
caught during the summer as well.
If the lake
trout take hold in Yellowstone Lake, the national park could be "on
the verge of an ecological disaster," " said
Lake trout pose a danger because they
are voracious, gobbling the smaller cutthroats, biologists say. The
lake trout could also upset the food chain that sustains
terrestrial wildlife from grizzly bears to birds of
The two species have opposite habits.
Cutthroat trout spawn in small streams each spring and live in
shallow waters. Lake trout spawn in the fall only in deep water and
live as deep as 100 feet below the surface.
feared that lake trout will be beyond the reach of predators who
depend on cutthroat trout. Grizzly bears feed on spawning
cutthroats after emerging from their winter hibernation. Birds,
including ospreys, pelicans and eagles, catch cutthroats in the
Biologists are probing the lake's
depths to determine how many lake trout might be present and how
long they have been around.
Park managers have
loosened regulations, allowing anglers to catch more fish, in hopes
that lake trout will be taken. But managers concede there may
already be too many of the lake trout to eliminate
If lake trout have been in the lake long
enough to reproduce, Kaeding says, it may take "nothing short of a
miracle'" to control them.
Rangers have posted a
$10,000 reward for information leading to an arrest and conviction
in the damaging transplant. Call 307/344-2281.
Milstein covers Wyoming for the Billings