In response to detection of IHN virus, Fish and Game hatchery staff at Magic Valley Fish Hatchery removed approximately 96,000 juvenile B-run steelhead from production. The IHN virus is not uncommon in southern Idaho fish, but the strain of the virus detected in the fish at the Magic Valley Hatchery is not known to be native to the area.
The virus was identified in routine health screening of the fish, which had been shipped as eggs from the Clearwater Fish Hatchery, located in Ahsahka, which is also operated by Fish and Game. The particular strain of IHN virus strain found in the fish that were removed is found in throughout much of the Pacific Northwest, including the Clearwater Basin.
To avoid potential amplification and spread of this strain of virus in the Magic Valley, fish in affected raceways at the Magic Valley Hatchery were euthanized the day after the viral detection was reported. Samples were collected from all other raceways at the facility to ensure that the virus has been eradicated. Approximately 1.5 million fish remain at the hatchery for continued rearing.
The euthanized B-run steelhead were scheduled to be released into the Little Salmon River as smolts in the spring of 2021. They represent approximately 12 percent of the planned 2021 Little Salmon River steelhead release of both A-run and B-run smolts.
Steelhead smolts released in the Little Salmon River are stocked solely for the purpose of providing fisheries on the returning adults. They are not collected for brood stock. For this reason, the reduction in stocking will not affect the next generation of hatchery releases. While this event is not expected to have a major impact on the number of returning adults, any effect will be observed primarily in the 2023-24 steelhead run.