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The Mountain-Prairie Region


U.S. Fish and Wildlife Service
134 Union Boulevard
Lakewood, Colorado 80228

June 11, 1999
Mike Stempel (CO) 303-236-7875, x248
Steve Krentz (ND) 701-250-4419
Crystal Hudson (MT) 406-582-8656
Sharon Rose (CO) 303-236-7917, x415


The U.S. Fish and Wildlife Service canceled its plans to release pallid sturgeons into the Missouri and Yellowstone Rivers this summer due to the recent detection of an unidentified virus in pallid and shovelnose sturgeon being raised in Service hatcheries.

"Preliminary studies show that it is likely this virus occurs naturally in the Missouri and Yellowstone Rivers. When the sturgeons are living in hatchery conditions it seems to appear in the juveniles when they are under stress," said Mike Stempel, fishery program supervisor in Denver for the Service’s Mountain-Prairie Region. "There is no evidence that would suggest the virus in the hatchery fish originated anywhere but the Missouri River basin, as only the two sturgeon species from the Yellowstone and Missouri Rivers were involved," Stempel added.

According to fish health biologists at the Bozeman Fish Health Center in Montana, at this stage in their lives and under hatchery conditions, the young fish are crowded and more likely to contract infections. Once the fish are weakened by an infection and under stress, the virus causes the fish to stop eating and growing. After initial recovery, all signs of the virus seem to disappear, and the fish do not suffer any ill effects or further occurrences. The virus has not been found in adult pallid or shovelnose sturgeon.

There have been no symptoms exhibited in the juvenile pallid sturgeon stocked in the Missouri and Yellowstone Rivers last year, and follow-up tests this spring showed no signs of the virus. However, to limit risks to fishery resources outside the Missouri River basin, the Service removed all sturgeon from the Valley City National Fish Hatchery in North Dakota because of its location in the Hudson Bay basin.

The Service hopes to have the results of DNA analysis to identify the virus within the next few weeks. That should reveal whether the virus in the pallid and shovelnose sturgeon is the same one that has been found in white sturgeon in waters of the northwestern United States for many years. In addition, extensive testing will be conducted throughout the summer to determine if the virus occurs naturally in the wild populations of the sturgeon of the Missouri River Basin. This knowledge is essential to future stockings.

By not reintroducing young pallid sturgeon this year, biologists involved with the recovery program for the pallid sturgeon will miss one year of telemetry research from young fish. That data would show what habitats the juvenile pallid sturgeon use, and would be important to the recovery of this species.

The pallid sturgeon was listed as endangered in 1990. The Service, along with partners in the recovery, developed a strategy to address the lack of natural reproduction. The first step called for stocking young sturgeon raised in hatcheries. In conjunction with the stockings, efforts to restore enough of the pallid’s habitat to allow them to reproduce naturally were used. Several hundred young pallids were released into the Missouri and Yellowstone Rivers in 1998. The few remaining wild pallid sturgeons have not reproduced in at least 20 years and are nearing the end of their life cycles.

Pallid sturgeon are grayish-white on the back and sides, can weigh up to 80 pounds and reach 6 feet in length. Their mouths are toothless and positioned under the snout for sucking small fishes and invertebrates from the river bottom. Pallids can live up to 50 years but mature and reproduce slowly.

Hatchery spawning activities for pallid sturgeon are planned over the next two weeks at Garrison Dam National Fish Hatchery in North Dakota and Gavins Point National Fish Hatchery in South Dakota. The young pallid sturgeon produced this year will be stocked in the fall of 2000 following disease clearance.

The U.S. Fish and Wildlife Service is the principal Federal agency responsible for conserving, protecting, and enhancing fish and wildlife and their habitats for the continuing benefit of the American people. The Service manages the 93-million-acre National Wildlife Refuge System comprised of more than 500 national wildlife refuges, thousands of small wetlands, and other special management areas. It also operates 66 national fish hatcheries, 64 fish and wildlife management offices, and 78 ecological services field stations. The agency enforces Federal wildlife laws, administers the Endangered Species Act, manages migratory bird populations, restores nationally significant fisheries, conserves and restores wildlife habitat such as wetlands, and helps foreign governments with their conservation efforts. It also oversees the Federal Aid program that distributes hundreds of millions of dollars in excise taxes on fishing and hunting equipment to state fish and wildlife agencies.

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