Nagler gathered the original Hanford Reach samples in fall 1999 and took additional samples in November 2000.

CNN: Something's fishy with chinook salmon

James Nagler, a University of Idaho assistant professor of zoology who led the study, said the results of the genetic testing on the natural-spawning chinook came as a surprise.

CNN: Something's fishy with chinook salmon

Pesticides and other chemicals that could mimic estrogen and disrupt the normal development of salmon are present in the Columbia's water, Nagler said, but at very low concentrations - far below those used in laboratory experiments.

CNN: Something's fishy with chinook salmon