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FY 2016 Program Highlights

DRIVEN BY SCIENCE

Fish, like people, are susceptible to the disease effects caused by viruses and bacteria. The Service's Fish Health Program works to ensure hatchery and wild fish populations remain as healthy and disease-free as possible.

Scientific Colaboration Combats A Deadly Steelhead Virus in Idaho

by Ben McLean, Guppy Blair, and Andy Goodwin, Division of Fish and Aquatic Conservation

The Dworshak National Fish Hatchery (NFH) is co-managed by the U.S. Fish and Wildlife Service and the Nez Perce Tribe. It is one of the largest producers of steelhead in the Snake River basin. The hatchery has historically relied on water pumped from the Clearwater River below the Dworshak Dam. Unfortunately, salmon and steelhead returning to the Clearwater River from the Pacific Ocean often carry a virus known as infectious hematopoietic necrosis virus, or IHNV. The virus can enter the hatchery with the pumped river water, and cause serious losses in juvenile steelhead.

Juvenile steelhead with IHNV.Steelhead fry infected with IHNV. The virus can be lethal to young fish. Credit: USFWS

Hatchery managers and fish health specialists have worked together to find a potential solution, noting that nearby Clearwater State Hatchery, which is operated by the State of Idaho, does not have losses from IHNV. The state facility gets its water from the reservoir above Dworshak Dam, where there are no ocean-run fish to transmit the virus. The State agreed to share some of its water source with Dworshak NFH while the Service's Idaho Fish Health Center worked with U.S. Geological Survey (USGS) scientists and the hatchery co-managers to better understand the virus.

Heathy versus IHNV infected fish cellsSlide comparrison of healthy (left) versus IHNV-infected (right) cells. Credit: USFWS

The USGS and Service scientists found that while the IHNV is present in the Clearwater for most of the year, the strain of the virus most dangerous to steelhead is only present during the first few months of juvenile rearing. The State now shares IHNV-free water with Dworshak NFH when the fish are in their first stages of life. Then, as fish grow and the State needs its full water supply, the Service's hatchery is able to switch over to its Clearwater River source when the more dangerous strain of IHNV is seasonally absent. Thanks to collaboration between the Service, the Tribe, the State, and the USGS, IHNV has not caused significant losses of steelhead at Dworshak NFH in recent years. It's a continued reminder of how scientific collaboration can and does work to support and protect wild as well as hatchery populations, including one of Idaho's most exciting and commercially valuable sport fisheries.

Idaho's B-run steelhead provide valueable recreational and tribal fisheries in Idaho.
Credit: USFWS

 

Last Updated: May 25, 2017
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