Denver (AP) Federal wildlife managers have rejected efforts to designate the Colorado River Cutthroat Trout as endangered.
Environmental groups plan to review the decision to decide if they should sue.
The U.S. Fish and Wildlife Service says there's evidence of a substantial increase in the number of known populations of the fish. Federal officials say data reviewed by experts show no major declines in the trout's overall distribution or abundance over the last several decades.
Environmental groups that think the Colorado River Cutthroat Trout should be designated as endangered.
Noah Greenwald of the Center for Biological Diversity says the fish is gone from 85 percent of its historic range, and most of the remaining trout are isolated in poor-quality habitat.