Severe thunderstorms producing heavy rain caused large amounts of sediment to flow into the South Fork Salmon River on August 6. The storms developed rapidly over the nearby mountains, choking the stream with sediment within minutes.
Fisheries managers say the sediment flowed into holding ponds at the South Fork Salmon trapping facility depriving the adult Chinook broodstock of oxygen. The sediment also caused some mortality to wild Chinook salmon swimming freely in the South Fork Salmon River.
Fish and Game and Nez Perce Tribe workers rushed tanker trucks to the trapping facility to save as many broodstock Chinook as they could after receiving word of the sediment flow. They were able to save approximately 200 adult Chinook, while an estimated 1,200 were lost.
"Broodstock losses will significantly impact the number of eggs for the IDFG McCall hatchery program, the Shoshone-Bannock egg box program, and the Nez Perce Tribe's Johnson Creek program in 2014," said Anadromous Fisheries Coordinator Sam Sharr.
In an effort to mitigate the impact of the losses on future runs, Fish and Game staff will join tribal staff to capture Chinook from the South Fork downstream from Fish and Game's trapping facility. The Nez Perce and Shoshone-Bannock tribes have volunteered to contribute a portion of their harvest share to the McCall Hatchery broodstock program.
Managers will continue monitoring mortality of wild Chinook salmon in the South Fork Salmon throughout the spawning season.