Lake Trout

History
Lake trout were first detected in 1994. Although their origin in Yellowstone Lake is unknown—biologists suspect an intentional, illegal transplantation—the species has apparently been present for nearly two decades.  Since that time, biologists have tried to learn as much as possible about this introduced species. Through angler returns and netting efforts, researchers have developed a picture of a well-established lake trout population that may number in the tens of thousands.

Threat
If the number of Lake Trout in Yellowstone Lake remain unchecked, it is feared that this highly piscivorous predator may decimate the native cutthroat population.

 Management Implications
Using information on lake trout feeding and spawning behavior, researchers developed a targeted and intensive gillnetting program that allows park personnel to annually harvest large numbers of the fish.

As part of a broader management strategy, park authorities have also opened the lake to fishing earlier in the season—from the traditional June 15 opener to June 1—in the hopes of increasing angler harvest of lake trout. By regulation, all lake trout that are landed must be kept and presented to a park ranger. Anglers may keep the fish once the identification is verified.

It is hoped that combined measures like these will hold the numbers of lake trout in check—or at least to levels that will substantially limit the impact on the cutthroat population. Indeed, there is growing confidence that this goal can be achieved. But the netting effort must be continued every year from now on.
 
References
National Park Service - Yellowstone National Park