Scientists working with Columbia River tribes tracked more than 7,000 of wild and hatchery Chinook salmon on Idaho's Johnson Creek over 13 years.
They used DNA to follow the offspring of wild fish that mated with hatchery fish and checked to see how well they reproduced.
Maureen Hess is the lead author on the study. She says the study didn't find a reduction in the reproductive fitness of those offspring.
"We are showing that they are surviving to reproduce and the ones that do reproduce are reproducing at a rate that is similar to the rate for wild fish," she said.
The findings contradict an earlier study that found hatchery fish are causing reproductive declines in steelhead on the Hood River.
Hess says the difference could be the result of different hatchery management practices at the two sites.
Her study was published today in the Journal of Molecular Ecology.