Sorry about my earlier post, my facts were wrong. Only the NC stocked rainbows are sterile. Apparently TN does not stock triploid trout, though I found it listed as one of the goals of their management plan.
"In a news statement from the folks at the North Carolina Wildlife Commission in Raleigh fisheries supervisor Mallory Martin has some interesting plans to share. Hatchery- raised trout stocked in NC streams beginning in 2009 won't experience parenthood. That's because all brook, brown, and rainbow trout will be sterile and unable to reproduce.
The NCWRC gradually has been shifting its production of trout from those that can produce fry to those that won't be able to spawn offspring.
The impetus for converting to sterile trout is to help preserve the native Southern Appalachian brook trout, said Mallory Martin, the commission's regional fisheries supervisor in Marion, NC."