BILLINGS, Mont. (AP) — Scientists say a voracious species of trout that entered Yellowstone Lake and decimated its native trout population appears to be in decline following efforts to kill off the invading fish. Non-native lake trout were first found 20 years ago in the 132-square mile lake in the center of Yellowstone National Park. Crews have since caught and removed more than a million of the fish in hopes that cutthroat trout populations would rebound. On Tuesday, scientists from the park and Trout Unlimited said those efforts are finally showing progress. They say a recent analysis points to a lake trout population beginning to decline. Meanwhile, the numbers of young cutthroat trout are increasing. Park officials expanded the lake trout removal program over the past two years. It costs about $2 million annually.