(CN) - The loss of historic habitat for the Colorado River cutthroat trout is not enough to grant federal protection, a federal judge ruled.
Despite being flushed out of 86 percent of what was once its home range, U.S. District Judge Paul Friedman upheld decisions by the U.S. Fish and Wildlife Service and the Department of Interior that identify the subspecies as healthy enough to survive on its own.
Noah Greenwald, the Center for Biological Diversity and a group named for the fish had sought to overturn both decisions.
They said that the groups had "failed to consider the trout's lost historic range" when judging the ongoing threat of encroachment.
Friedman explained that, about 200 years ago, "the trout occupied a range of approximately 21,386 stream miles, running through Wyoming, Colorado, Utah, New Mexico, and possibly Arizona. Currently, the trout occupies 3022 miles, or 14%, of its historic range, and is found in Colorado, Utah, and Wyoming."
Friedman acknowledged that the Endangered Species Act compels the government to designate a species as "threatened" or "endangered" if it faces the possibility of "the present or threatened destruction, modification, or curtailment of its habitat or range," among other factors.
But the court agreed with the Fish and Wildlife Service's assertion that the trout's historic range is irrelevant today.
In 2007, the service said that "the principal considerations in the determination of whether or not a species warrants listing as a threatened or an endangered species under the act are the threats that now confront the species and the probability that the species will persist in 'the foreseeable future.'"
"We evaluated the [Colorado River cutthroat trout] throughout its current range to determine if any portion is likely to become threatened or endangered within the foreseeable future, and if so, whether that portion is significant relative to the remainder of the species' range," according to the agency's finding.
The environmentalists argued that the cutthroat's current range is threatened just the same.
"Plaintiffs point to the 1226 miles throughout the current range that lack populations of genetically pure (or close-to-pure) trout and argue that the FWS 'failed to evaluate the significance of the fact that almost half of its remaining range is unoccupied,'" Friedman wrote.
The lack of "genetically pure" populations of Colorado River cutthroat trout in its current range largely comes down to "the stocking of nonnative sport fish, which 'caused problems through hybridization, competition, and predation,'" the 33-page opinion says.
While Friedman acknowledged the credibility of these threats, he ultimately sided with a Fish and Wildlife report finding that, across the 1,226 miles in question, enough pockets of the cutthroat "were likely to survive," ending any question of federal involvement.
The judge noted also shot down claims that the government had failed to consider the potential effects of climate change upon the species' numbers.
"Plaintiffs argue that 'climate change will cause significant additional reductions in suitable habitat and will especially impact the majority of the conservation populations because of their small size," according to the ruling.
But Friedman noted that the Fish and Wildlife Service had found that "if global climate change results in shrinkage of [trout] habitat to higher elevations ... there may be opportunity to establish new self-sustaining populations in lakes and streams that were previously too cold for trout recruitment." Friedman's is the latest ruling in a long-running feud over the fish's protective status.
In 2004, a court ordered the Fish and Wildlife Service to conduct a year-long study on the topic after Greenwald and the Center for Biological Diversity had filed suit against it in 2000.
That report, published in 2007, formed the basis of much of Friedman's opinion.