BEN KOCH

Perspective

There is a disturbing trend in our state. From the Absarokas to the Snowies, interlopers are marginalizing Wyoming natives.

Wyoming's waters harbor six exotic species of trout. They are found in creeks, rivers, lakes, and reservoirs throughout the state. In contrast, the single native species, the cutthroat, maintains a tenuous existence in but a fraction of its original range. Six of its different sub-species (the Yellowstone, Bonneville, Westslope, Greenback, Snake River, and Colorado River cutthroat trout) used to ply the clear, cool waters of the entire southern edge and western half of the state. Only five remain, occurring only in the isolated upper reaches of a handful of mountain streams. Exotics like the brookie and the brown, on the other hand, hailing from the eastern United States and Europe respectively, now cruise waters in every one of Wyoming's five major drainages.

Without a doubt, exotic trout bring immense pleasure to fishermen throughout Wyoming and beyond. Indeed, ad campaigns promoting tourism to the state have urged vacationers to travel west and "stalk the secretive brown and the acrobatic rainbow." The anglers that do so bring in a whopping $5 million to state coffers each year. So why should we be concerned at all about these lithe and lucrative sport fish?

The fisherman's thrills have come at a cost. Exotic trout roil the waters with a specter of ecological havoc.

Beneath the beautiful stripes and spots of the exotic rainbow or brown trout lurks an aggressive bully with a big libido. These invaders beat up the natives and push them out of the best habitats. Adding insult to injury, alien trout interbreed with the cutthroat and dilute them into genetic limbo. All of this further reduces the distribution of a native species already beleaguered by habitat loss, disease, and pollution.

Secondly, with the help of humans, exotic trout have achieved the piscine equivalent of flying to the moon. They now inhabit turquoise alpine lakes perched on mountain slopes above 11,000 feet and raging headwater streams that have lacked fish in their entire 12,000-year history. As a consequence, the native amphibians and insects dwelling in these high-elevation sanctuaries have suffered catastrophic losses. For the hungry trout newcomers, devouring these naïve creatures is like shooting fish in a barrel.

Amazingly, exotic trout can threaten animals that don't even live in the water. In mountain streams of Japan, which are similar to the ones found throughout the Wind Rivers or the Bighorns, the introduction of exotic rainbow trout has initiated an ecological "domino-effect" that extends up the riverbank and into the surrounding landscape. Birds and spiders that make their living off of the insects that hatch from the river have declined where rainbows were introduced. Could a similar chain reaction be affecting the dippers, flycatchers, and bats in our own backyard?

Exotic trout can fundamentally alter even the most revered of our state's waters. In Yellowstone Lake, voracious lake trout, introduced by unknown parties in the late 1980s, have caused massive declines among native Yellowstone cutthroat trout. Spawning cutthroat that once ascended by the tens of thousands the streams and creeks feeding Yellowstone Lake are dwindling. The loss of these giant native fish portends troubling times for many of Yellowstone's wildlife species, such as grizzlies and river otters, which have depended on the abundant cutthroat for millennia.

What can the conscientious fisherman do to help mitigate the impacts of exotic trout?

First, know the natives. Learn which local fishing holes sustain pristine native fisheries and which harbor exotics. The Wyoming Game and Fish Department's Cutt-Slam Program is designed to encourage anglers to do exactly this.

Second, talk to WGFD personnel. The more they hear about angler interest in natives, the more resources they'll devote to protect and restore these fish. One prominent cutthroat restoration project is already nearing completion in LaBarge Creek, in the Wyoming Range.

Finally, get involved. Organizations such as Trout Unlimited, The Nature Conservancy, and the Western Native Trout Initiative provide dozens of opportunities for us to help protect native fishes for future generations. As citizens of a state that boasts many of the most pristine and biologically rich inland waters of the American West, we can't afford not to.

Ben Koch is a graduate student studying aquatic ecology at the University of Wyoming.