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What percentage of salmon that cross Lower granite survive to Idaho hatcheries? Not counting harvested fish. Just a % number that will survive the journey

Answer

Natural mortality (excluding harvest) for salmon between Lower Granite Dam and hatchery facilites varies by facility and year but typically is not more than 5%. So if  there were no harvest in Idaho and 10,000 hatchery fish crossed Lower Granite Dam 9,500 or more would make it back to hatcheries. Some portion of the 5% that do not make it back to hatcheries die or are eaten by predators during their upstream migration and others stray into other streams and spawn naturally.