Biologists Take Big Step to Keep Park's Little Cutthroats From Being Devoured
By JIM ROBBINS
YELLOWSTONE NATIONAL PARK, Wyo. - An unusual fishing season just ended on Yellowstone Lake. The take included 36,000 lake trout caught, killed and sunk to the bottom of the lake.
Anne Sherwood for The New York Times
Nicole Schamberry cleans gill nets near Yellowstone Lake.
Anne Sherwood for The New York Times
Bob Gresswell, a biologist, emphasizes diverse behavior in saving species.
And the fishers are not finished.
"We'll hit them like this as hard as we can for the next several years, until we find a technology that kills them better," Pat Bigelow said, as she and other researchers cleaned and put away miles of net.
Ms. Bigelow, a fisheries biologist for the National Park Service, heads a campaign that begins each May and continues until October and is part of a plan to protect the Yellowstone cutthroat trout, a candidate for listing as an endangered species.
Yellowstone Lake, the largest in the park, was one of the last strongholds of the Yellowstone cutthroat, a subspecies of trout that has disappeared from more than half of its range.
The lake was considered the trout's stronghold until 1994, when a fisherman reeled in a lake trout and showed it to the authorities. Park biologists were horrified. Lake trout are voracious predators, growing to more than 20 pounds and eating smaller fish like the cutthroats.
At the time, 80 percent of the world's remaining pure Yellowstone cutthroats lived in the 87,000-acre lake.
The population of cutthroats in the lake crashed. In Clear Creek, a tributary, as many as 70,000 fish used to spawn.
Last year, the number was 500. In 1999 in Bridge Creek, 2,300 cutthroat spawned. Last year, a single fish made the trip.
In five years of aggressive fishing with miles of drift nets and electric shocks, biologists have killed more than 136,000 lake trout. Fishers are also allowed to catch and kill as many lake trout as they want.
As a result, in the last couple of years there has been a tiny increase in the cutthroat population, though it is too early to be optimistic, officials say. "When you cut out their stomachs and see cutthroat trout inside, it makes you feel good about the impact we're having," said Anna Varian, who works in the fishing crew.
But lake trout may never be eradicated, and officials may always need to remove them. If no better technology emerges, the fishing will have to continue perpetually to save the Yellowstone cutthroat.
The lake trout probably came from nearby Lewis Lake, though no one knows how. Fishers could have furtively transplanted them to create a larger lake trout fishery, or a firefighting helicopter carrying water from Lewis Lake could have inadvertently dropped an invader into Yellowstone Lake.
The cutthroats, beautiful gold fish with a pinkish cast and a scarlet slash next to the gills, have also been hit hard by whirling disease, which attacks the nervous system. Hybridization with rainbow trout is another problem. The threat to Yellowstone cutthroats, one of 14 subspecies of indigenous Western cutthroats, is the most serious of many problems faced by native trout in the Rockies.
The problems began with the introduction in the 19th century of three exotic species - the rainbow, brown and brook trout, from California, Europe and the East Coast, respectively. They pushed the natives out of lower elevation lakes and rivers.
In recent years, genetic diversity has become an important goal of fisheries managers. "Diversity is key to persistence though time," said Bob Gresswell, a research biologist with the United States Geological Survey's Northern Rocky Mountain Science Center in Bozeman, Mont.
Diverse genes mean diverse behaviors, and some of those actions may help species survive. "Some fish swim miles to spawn, and others spend their life within 100 meters," Mr. Gresswell said.
State and federal biologists have taken steps to protect native trout and reintroduce them to some rivers and streams where they once lived. Cutthroats, which evolved in cold waters without much food, eat anything that floats by. As a result, they are too easy to catch, and some anglers have opposed their reintroduction.
The technique for restoring native trout to a stream is first to poison the fish living there. For years, opponents fought the efforts of the state of Montana to poison exotic fish like brook trout in Cherry Creek, a tributary of the Madison River, so that they could restore the imperiled native westslope cutthroat trout. The project went ahead in 2002, and after three years, a third of 60 miles of stream has been cleaned out and restocked with natives.
Dr. Robert J. Behnke, an emeritus professor of fisheries biology from Colorado State University, is cautiously optimistic about the long-term outlook for natives, saying, "They've suffered really great declines, though I wouldn't call them on the verge of extinction" in most places.
Concern about the Yellowstone cutthroat has led to a campaign by the Greater Yellowstone Coalition and other groups to keep 500 miles of the headwaters of the river as a federally protected wild and scenic river.
"It's one of the last, best refuges for these native fish in the Rocky Mountains," said Scott Bosse, a fish biologist who works for the coalition.
By JIM ROBBINS
YELLOWSTONE NATIONAL PARK, Wyo. - An unusual fishing season just ended on Yellowstone Lake. The take included 36,000 lake trout caught, killed and sunk to the bottom of the lake.
Anne Sherwood for The New York Times
Nicole Schamberry cleans gill nets near Yellowstone Lake.
Anne Sherwood for The New York Times
Bob Gresswell, a biologist, emphasizes diverse behavior in saving species.
And the fishers are not finished.
"We'll hit them like this as hard as we can for the next several years, until we find a technology that kills them better," Pat Bigelow said, as she and other researchers cleaned and put away miles of net.
Ms. Bigelow, a fisheries biologist for the National Park Service, heads a campaign that begins each May and continues until October and is part of a plan to protect the Yellowstone cutthroat trout, a candidate for listing as an endangered species.
Yellowstone Lake, the largest in the park, was one of the last strongholds of the Yellowstone cutthroat, a subspecies of trout that has disappeared from more than half of its range.
The lake was considered the trout's stronghold until 1994, when a fisherman reeled in a lake trout and showed it to the authorities. Park biologists were horrified. Lake trout are voracious predators, growing to more than 20 pounds and eating smaller fish like the cutthroats.
At the time, 80 percent of the world's remaining pure Yellowstone cutthroats lived in the 87,000-acre lake.
The population of cutthroats in the lake crashed. In Clear Creek, a tributary, as many as 70,000 fish used to spawn.
Last year, the number was 500. In 1999 in Bridge Creek, 2,300 cutthroat spawned. Last year, a single fish made the trip.
In five years of aggressive fishing with miles of drift nets and electric shocks, biologists have killed more than 136,000 lake trout. Fishers are also allowed to catch and kill as many lake trout as they want.
As a result, in the last couple of years there has been a tiny increase in the cutthroat population, though it is too early to be optimistic, officials say. "When you cut out their stomachs and see cutthroat trout inside, it makes you feel good about the impact we're having," said Anna Varian, who works in the fishing crew.
But lake trout may never be eradicated, and officials may always need to remove them. If no better technology emerges, the fishing will have to continue perpetually to save the Yellowstone cutthroat.
The lake trout probably came from nearby Lewis Lake, though no one knows how. Fishers could have furtively transplanted them to create a larger lake trout fishery, or a firefighting helicopter carrying water from Lewis Lake could have inadvertently dropped an invader into Yellowstone Lake.
The cutthroats, beautiful gold fish with a pinkish cast and a scarlet slash next to the gills, have also been hit hard by whirling disease, which attacks the nervous system. Hybridization with rainbow trout is another problem. The threat to Yellowstone cutthroats, one of 14 subspecies of indigenous Western cutthroats, is the most serious of many problems faced by native trout in the Rockies.
The problems began with the introduction in the 19th century of three exotic species - the rainbow, brown and brook trout, from California, Europe and the East Coast, respectively. They pushed the natives out of lower elevation lakes and rivers.
In recent years, genetic diversity has become an important goal of fisheries managers. "Diversity is key to persistence though time," said Bob Gresswell, a research biologist with the United States Geological Survey's Northern Rocky Mountain Science Center in Bozeman, Mont.
Diverse genes mean diverse behaviors, and some of those actions may help species survive. "Some fish swim miles to spawn, and others spend their life within 100 meters," Mr. Gresswell said.
State and federal biologists have taken steps to protect native trout and reintroduce them to some rivers and streams where they once lived. Cutthroats, which evolved in cold waters without much food, eat anything that floats by. As a result, they are too easy to catch, and some anglers have opposed their reintroduction.
The technique for restoring native trout to a stream is first to poison the fish living there. For years, opponents fought the efforts of the state of Montana to poison exotic fish like brook trout in Cherry Creek, a tributary of the Madison River, so that they could restore the imperiled native westslope cutthroat trout. The project went ahead in 2002, and after three years, a third of 60 miles of stream has been cleaned out and restocked with natives.
Dr. Robert J. Behnke, an emeritus professor of fisheries biology from Colorado State University, is cautiously optimistic about the long-term outlook for natives, saying, "They've suffered really great declines, though I wouldn't call them on the verge of extinction" in most places.
Concern about the Yellowstone cutthroat has led to a campaign by the Greater Yellowstone Coalition and other groups to keep 500 miles of the headwaters of the river as a federally protected wild and scenic river.
"It's one of the last, best refuges for these native fish in the Rocky Mountains," said Scott Bosse, a fish biologist who works for the coalition.
