Study: Yellowstone cutthroat trout stable, face threats

Matthew Brown, Associated Press

Thursday, July 19, 2007

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 of 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 handbasket."

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 compared with 1900 and can be found in 7,527 miles of streams and rivers in western Wyoming, eastern Idaho and south-central Montana.

The Fish and Wildlife Service put that figure much lower in a 2003 study, at 6,352 miles of occupied habitat. Fredenberg said different research methods preclude a direct comparison of the two figures.

"Things look about like they did five years ago," he added.

The 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 of the Wyoming Department of Game and Fish said his agency was trying to address that problem, in part, by killing off 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.