In the midst of a building storm, Joseph Blackburn checked on the chinook salmon in the Powell trap with a flashlight about 1 a.m., Aug. 6 and did not see any dead fish.
But later that morning Blackburn, the Powell trap attendant, notified Idaho Fish and Game officials that half the fish in the adult chinook female pond had been killed during the night.
Apparently 141 fish, scattered the full length of the all female pond, had been electrocuted.
A violent thunder and lightning storm during the night had lasted three to four hours. Blackburn reported lightning strikes so close to the cabin that they lit up the room as if it were daytime.
He had cleaned the screens during the storm and checked the flows through the ponds. Flow was never lost or reduced to the holding ponds.
A trap attendant had contacted the U.S. Forest Service Powell Ranger Station and their satellite imaging confirmed that at least three lightning strikes occurred in proximity of the cabin and holding ponds.
Fish and Game fishery biologists can't remember a hatchery ever being hit by lightning, electrocuting fish.
"We've never seen this," said Paul Kline, assistant chief of fisheries at IDFG.
Doug Munson, IDFG's fish pathologist, and Clearwater Hatchery superintendent Jerry McGehee went to the Powell trap to investigate.
They found dead fish scattered randomly the entire length of the holding pond. Some were bent in a slight "C" shape, and many of them had black bruised areas on their backs and sides.
When they dissected the area under the bruise marks, they found hemorrhages.
Some were localized while others ran laterally along the spine. Internal organs also were traumatized and hemorrhaged. These signs are similar, though more severe, to those occasionally observed by biologists who routinely use electro-fishing equipment to sample fish populations.
The fish kill at the Powell trap is not expected to affect the number of fish produced at the Clearwater Hatchery. Because of the abundant return of adult chinook to Idaho this year, IDFG will be able to get eggs from other hatcheries to make up for the loss of fish at Powell.