BILLINGS, Mont. – Yellowstone cutthroat trout are "holding their own" in Montana, Idaho and Wyoming despite threats ranging from habitat loss and disease to hybridization with other species, state and federal fisheries biologists said Wednesday.
The biologists said their findings, in a new study described as the most sweeping assessment of the popular game fish to date, support a federal decision last year not to put the fish under Endangered Species Act protections. Environmental groups have pushed for such a listing on the argument that Yellowstone cutthroat are in the midst of a drastic population decline.
Wade Fredenberg with the U.S. Fish and Wildlife Service said the latest data refute that claim.
"The rate of decline in recent years has slowed, and there's good evidence of that," he said. "Things aren't going to hell in a hand basket."
The study was carried out in 2006 by Fredenberg's agency and fisheries experts from the three states. It found the trout occupy about 43 percent of their range versus 1900, and can now be found in 7,527 miles of streams and rivers in western Wyoming, eastern Idaho and south-central Montana.
In a 2003 study, the Fish and Wildlife Service estimated occupied habitat covered 6,352 miles. Fredenberg said different research methods preclude a direct comparison of the two numbers.
"Things look about like they did five years ago," he added.
In 1998, Montana Ecosystems Defense Council and other environmental groups petitioned the Fish and Wildlife Service to list the Yellowstone cutthroat as threatened. The service rejected the petition in 2001.
A court challenge forced a second look in 2005, and in February 2006 the agency again said the trout did not warrant listing.
Steve Kelly, with Montana Ecosystems Defense Council, called the new study an example of "government double-talk."
"The government likes to play this numbers game with population numbers," he said. "You're still declining and you've only slowed the rate and the habitat is in terrible shape."
The new study also provided an unprecedented look at cutthroat trout genetics — an indication of how quickly nonnative species such as rainbow trout are hybridizing with cutthroat and diluting their genetic purity.
Of 383 distinct populations of the fish, more than half were at a moderate to high risk of being hybridized, the study found.
Steve Yekel with the Wyoming Department of Game and Fish said his agency was attempting to address that problem, in part, by killing brook trout in some streams and using only sterile fish to restock nonnative species.
Yellowstone cutthroat also have suffered from whirling disease, habitat loss, competition with nonnative species and other factors.
"It's definitely historically down from what it was," said Scott Grunder with Idaho Fish and Game. "But in some areas we're stable, in some areas we're declining, in others we're expanding. Right now we're holding our own."