posted 429/04
Fish disease causes park area closure
Associated Press
CHEYENNE, Wyo. - A parasite that causes trout to swim in circles has prompted Yellowstone National Park to prohibit fishing in a drainage that empties into Yellowstone Lake.
The angling season for the Pelican Creek drainage, a 50-square-mile area on the north end of Yellowstone Lake, was scheduled to begin May 29. It is unknown when fishing might resume in the drainage, Chief Fisheries Biologist Todd Koel said Wednesday.
Not that anglers would have much luck, anyway. Because of whirling disease, few fish are left in the creek.
For decades the U.S. Fish and Wildlife Service maintained a fish trap near the creek mouth and counted Yellowstone cutthroat trout that entered the stream from Yellowstone Lake to spawn. In the early 1980s, about 30,000 fish migrated into the stream each year.
In August, 2002 - a time of year when the creek would be expected to be teeming with very young fish - researchers found no fry in the lower seven miles of the creek. Last August, they counted just nine fry.
"They're just not there anymore," Koel said. "The fish are gone."
Whirling disease was first detected in Yellowstone in 1998. Park officials theorize that the whirling disease parasite, which is native to Europe and has been spreading across the United States since 1956, might have hitched a ride into the park on someone's fishing gear.
The goal of the closure is twofold: to prevent whirling disease from spreading to new areas and to help the stream recover. "We need to protect those remaining fish so we can get the population back to what it was," Koel said.
Besides the Pelican Creek drainage, whirling disease has been found in Clear Creek on the lake's east side, in the Yellowstone River at Fishing Bridge and in the lake itself. But Pelican Creek has been affected worst.
Whirling disease is caused by a tiny parasite, Myxobolus cerebralis, which lives in fish and an aquatic worm, Tubifex tubifex. The parasite damages cartilage in young fish, causing nerve damage that kills the fish directly or causes them to spin, making them vulnerable to predators.
Of the fish placed in a cage in Pelican Creek to test infection rates, 90 to 100 percent got whirling disease. That gives the creek a 4 on a 1-to-5 scale for whirling-disease infection.
The Yellowstone River, in comparison, gets a 2½. "It's considered a moderate infection, but maybe not enough to create a population decline," Koel said. Infection rates in Clear Creek are also low.
Koel theorizes that Pelican Creek's warm water and relatively muddy bottom make it a good habitat for the tubifex worm, whereas cooler and rockier streams are less hospitable for the species.
Fish disease causes park area closure
Associated Press
CHEYENNE, Wyo. - A parasite that causes trout to swim in circles has prompted Yellowstone National Park to prohibit fishing in a drainage that empties into Yellowstone Lake.
The angling season for the Pelican Creek drainage, a 50-square-mile area on the north end of Yellowstone Lake, was scheduled to begin May 29. It is unknown when fishing might resume in the drainage, Chief Fisheries Biologist Todd Koel said Wednesday.
Not that anglers would have much luck, anyway. Because of whirling disease, few fish are left in the creek.
For decades the U.S. Fish and Wildlife Service maintained a fish trap near the creek mouth and counted Yellowstone cutthroat trout that entered the stream from Yellowstone Lake to spawn. In the early 1980s, about 30,000 fish migrated into the stream each year.
In August, 2002 - a time of year when the creek would be expected to be teeming with very young fish - researchers found no fry in the lower seven miles of the creek. Last August, they counted just nine fry.
"They're just not there anymore," Koel said. "The fish are gone."
Whirling disease was first detected in Yellowstone in 1998. Park officials theorize that the whirling disease parasite, which is native to Europe and has been spreading across the United States since 1956, might have hitched a ride into the park on someone's fishing gear.
The goal of the closure is twofold: to prevent whirling disease from spreading to new areas and to help the stream recover. "We need to protect those remaining fish so we can get the population back to what it was," Koel said.
Besides the Pelican Creek drainage, whirling disease has been found in Clear Creek on the lake's east side, in the Yellowstone River at Fishing Bridge and in the lake itself. But Pelican Creek has been affected worst.
Whirling disease is caused by a tiny parasite, Myxobolus cerebralis, which lives in fish and an aquatic worm, Tubifex tubifex. The parasite damages cartilage in young fish, causing nerve damage that kills the fish directly or causes them to spin, making them vulnerable to predators.
Of the fish placed in a cage in Pelican Creek to test infection rates, 90 to 100 percent got whirling disease. That gives the creek a 4 on a 1-to-5 scale for whirling-disease infection.
The Yellowstone River, in comparison, gets a 2½. "It's considered a moderate infection, but maybe not enough to create a population decline," Koel said. Infection rates in Clear Creek are also low.
Koel theorizes that Pelican Creek's warm water and relatively muddy bottom make it a good habitat for the tubifex worm, whereas cooler and rockier streams are less hospitable for the species.
